Hazmat Terms and Definitions

Abandoned

Permanently removed from service

Source: §192.3, §195.2


Abandoned pipeline

A pipeline permanently removed from service that has been physically separated from its source of gas or hazardous liquid and is no longer maintained under regulation 49 CFR Parts 192 or 195, as applicable. Abandoned pipelines are usually purged of the gas or liquid and refilled with nitrogen, water, or a non-flammable slurry mixture.

Source: GPTC


Abnormal operating condition

A condition identified by the operator that may indicate a malfunction of a component or deviation form normal operations that may:

  1. Indicate a condition exceeding design limits; or
  2. Results in a hazard(s) to persons, property, or the environment.

Source: §192.803, §195.503


Abnormal operation

Exceeding operating design limits, including:

  1. unintended closure of valves or shutdowns;
  2. increase or decrease of flow rate outside of normal operating limits;
  3. loss of communications;
  4. operation of any safety device; and
  5. any other foreseeable malfunction of a component, deviation from normal operation, or personnel error which may result in a hazard to persons or property.

Source: §192.605(c), §195.402(d)


Abrasion resistance

The ability of a coating to resist being worn away and to maintain it’s original appearance and structure when subjected to rubbing, scraping, or wear.

Source: NACE/ASTM G193 Corrosion Terms


Abrasive blast cleaning

Cleaning and roughening of a surface produced by the high-velocity impact of an abrasive that is propelled by the discharge of pressurized fluid from a blast nozzle or by a mechanical device such as a centrifugal blasting wheel (also referred to as abrasive blasting).

Source: NACE/ASTM G193 Corrosion Terms


Accessible to public

An area is accessible to the public if entrance into the area is not physically controlled by the operator and may be entered without difficulty (i.e. – does not have any man-made or natural impediments to prevent public access).

Source:PHMSA interpretation PI-91-022


Accident

A release of the hazardous liquid or carbon dioxide transported that results in any of the following:
(a) explosion or fire not intentionally set by the operator.
(b) release of 5 gallons (19 liters) or more of hazardous liquid or carbon dioxide, except that no report is required for a release of less than 5 barrels (0.8 cubic meters) resulting from a pipeline maintenance activity if the release is:
(1) not otherwise reportable under this section;
(2) not one described in Sec 195.52(a)(4);
(3) confined to company property or pipeline right-of-way; and
(4) cleaned up promptly
(c) Death of any person;
(d) personal injury necessitating hospitalization;
(e) estimated property damage, including cost of clean-up and recovery, value of lost product, and damage to the property of the operator or others, or both, exceeding $50,000.

Source: §195.5


Acid producing bacteria (APB)

Bacteria that produce organic acids as an end product of their metabolism, which may be aerobic (live in the presence of oxygen) or anaerobic (absence of oxygen).

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Active corrosion

Continuing corrosion which, unless controlled, could result in a condition that is detrimental to public safety or the environment.

Source: §192.3, §195.553


Actual wall thickness

The measured wall thickness of pipe from its inner surface to its outer surface. For new pipe, this measured dimension must be within tolerances stated in the manufacturer’s specifications. Actual wall thickness of installed pipe can be determined by using an ultrasonic thickness (UT) gauge.


Adhesion

The state in which two surfaces are held together by interfacial forces, which may consist of chemical or interlocking forces, or both.

Source: NACE/ASTM G193 Corrosion Terms


Adhesive joint

A joint made on certain types of plastic piping by the use of an adhesive substance which forms a bond between the mating surfaces without dissolving either one of them.

Source: GPTC


Administrator

The Administrator, Pipeline Hazardous Materials Safety Administration or his or her delegate.

Source: §190.3, §192.3, §195.2


Aerial crossing

Where a pipeline crosses over a river, deep gully, or other geographic feature, and is not buried or submerged in water but is exposed to atmosphere. The pipeline may be suspended by cables, attached to the girders of a bridge, or, for short crossings, engineered to support itself.


Aerobic bacteria

Bacteria that grow and reproduce in the presence of oxygen.

Source: NACE TM0194 Internal Corrosion


Airless spraying

Process of spraying coating liquids using hydraulic pressure, not air pressure, to atomize.

Source: NACE/ASTM G193 Corrosion Terms


Alarm

An audible or visible means of indicating to the controller that equipment or processes are outside operator-defined, safety-related parameters.

Source: §192.3, §195.2


Alternating current (AC)

An electrical current whose direction or polarity changes with time. The polarity or cycles are due to the alternating magnetic fields used in its generation. The time frequency cycle is also referred to as hertz. In North America, the common frequency is 60 hertz (cycles per second).


Alternating current voltage gradient (ACVG)

A method of measuring the change in electrical voltage gradient in the soil along and around a pipeline to locate coating holidays and characterize corrosion activity.

Source: ANSI/NACE SP0502


Ambient temperature

The temperature of the surrounding air or environment. This thermal condition is often referenced to calculate how it might affect the design or operation of various devices on the pipeline.


Amphoteric metal

A metal that is susceptible to corrosion in both acidic and alkaline environments.

Source: NACE/ASTM G193 Corrosion Terms


Anaerobic bacteria

Bacteria that grow and reproduce in the absence of oxygen.

Source: NACE TM0194 Internal Corrosion


Anhydrous ammonia (NH3)

A toxic colorless gas with a pungent-suffocating odor under atmospheric conditions. It is normally shipped in a compressed liquid state and is considered to be a hazardous liquid. It will burn skin if touched and can be deadly if inhaled.


Anode

The electrode in a corrosion cell where oxidation or corrosion occurs. In a pipeline-related cathodic protection (CP) system, the anode is designed as the sacrificial material installed to purposely corrode and protect the structure (pipeline, tank bottom, or other underground structure). There are two basic type of anodes: the galvanic and the impressed current types.


Anode

The electrode of an electrochemical cell at which oxidation (corrosion) occurs. Antonym: cathode.
Oxidation in this sense indicates an electrical potential that is becoming more positive. This indicates that this area of the electrical circuit is loosing electrons and, therefore, referred to as oxidizing (corrosion) or an oxidation reaction is occurring.

as used in Introduction to Aboveground Storage Tanks WBT
Source: API RP 651


Anode (ground) bed

One or more anodes installed below the earth’s surface for the purpose of supplying cathodic protection.

Source: NACE SP0169


Anodeless riser

A plastic pipe sheathed inside a protective steel metallic casing. The steel-cased plastic pipe protrudes from the soil and is part of the service line carrying gas to the customer meter. An anode is not required in this instance because the plastic pipe contains the gas pressure and is not susceptible to the typical corrosive processes.


Anomaly

Any kind of imperfection, defect, irregularity, or deviation from the normal that may be present in either measurements or the physical facility.


Anti-rotation device

A stopping device that is commonly fastened to both the tank roof and floor. This device is rigid and often is constructed of pipe or cable. Anti-rotation devices are required in open and covered floaters to prevent rotation of floating roofs.

as used in Introduction to Aboveground Storage Tanks WBT


Appurtenance

Any part of a pipeline that may be subjected to pump or compressor discharge pressure including, but not limited to, pipe, valves, fittings, flanges, and closures.


Assessment

The use of testing techniques as allowed in this subpart (O) to ascertain the condition of a covered pipeline segment.

Source: §192.903


Atmospheric storage tank

Tanks designed for pressures that are approximately equal to that of the atmosphere.

as used in Introduction to Aboveground Storage Tanks WBT


Backfilling

The technique for covering a newly constructed or recently unearthed pipeline so that adequate fill material is provided and compacted around the pipe to completely fill the excavation. The fill material must be suitable and free of rocks and other debris to prevent damage to the coating and the pipe. Rock shield, concrete and other coating methods may help protect the pipe during backfilling. Proper backfilling is critical so that the pipe is properly supported and not subjected to added stresses due to soil subsidence or movement.


Ball valve

A valve in which a solid metal sphere with a hole in the center rotates within the valve body to control the flow of fluids. The ball usually rotates within a set of sealing rings.


Barhole

A small diameter hole in the ground made by a plunger bar or probe. These holes are made along the route of a gas pipeline to check the subsurface soil for an indication of gas accumulations due to leaks or to check the depth of pipe.


Barlow’s formula

P= 2St/D
The mathematical formula that calculates the relationship of internal pressure to allowable stress, nominal thickness, and diameter of the pipe. Simply stated, Barlow’s Formula calculates the pressure containing capabilities of pipe. The formula takes into account the pipe diameter (D), wall thickness (t), and the manufacturer’s specified minimum yield strength of the pipe (S).


Barrel

42 United States gallons (159 liters) at 60° Fahrenheit (15.6° Celsius)

Source: §194.5


Barrel

A unit of liquid petroleum measurement equal to 42 U.S. standard gallons.

Source: §195.2


Barrier coating

  1. A coating that has a high resistance to permeation of liquids and/or gases.
  2. A coating that is applied over a previously coated surface to prevent damage to the underlying coating during subsequent handling.

Source: NACE/ASTM G193 Corrosion Terms


Baseline Assessment Plan (BAP)

For integrity management, a written plan that identifies for each covered segment, the potential threats, the methods of assessment for the threats, and a schedule for completing the integrity assessments.

Source: §192.919, §195.452(c)


Basic sediment and water (BS&W)

A test made on fuel oil or crude oil to show the approximate amount of sediment and water contained in the sample.


Batch

A quantity of one type of product or material pumped within a pipeline. Often different types of crude oils or products, known as “batches,” are pumped in front of or behind one another within the same pipeline. Depending on the physical characteristics of the crude or products, the batches may stay relatively separate or mix (commingle) as they travel within the pipeline. Batch sizes can vary between a few hundred barrels to hundreds of thousands of barrels.


Batching

Batching is the process of pumping a certain quantity of crude oil or petroleum product next to one of a different type. As different batches arrive at their destinations, valves are opened and closed to divert the different products to the correct locations, such as tanks or even other customer pipelines.


Bell hole

An enlarged hole other than a continuous trench, dug over and along the side of buried pipelines or in a trench to allow room for persons to perform maintenance-related work on the pipeline (i.e., coating repairs, welding, connections, or pipe replacement). In the broad sense, any larger hole, other than a ditch, opened for pipeline work. Smaller holes may be called key holes or pot holes.


Berm

A raised mound of soil usually placed around structures to form a dam such as those used around tanks for containing possible spills or overflows.


Biocide

A chemical product that is intended to kill or render harmless biological organisms.

Source: NACE TM0194 Internal Corrosion


Biofilm

A matrix of bacteria, exopolymer, debris, and particulate matter that adheres to a surface.

Source: NACE TM0194 Internal Corrosion


Biofilm

In oil and gas pipelines, an established layer of microorganisms, consisting of produced exo-polymers, lipids, and metabolic waste products; often containing corrosion products and debris. Films may range from 5 microns to over 100 microns in thickness. Various bacterial species may be present within the biofilm and form synergistic chemical and structural relationships.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Blister

A dome-shaped projection on the surface of a coating resulting from the local loss of adhesion and lifting of the film from an underlying coat or from the base substrate.

Source: NACE/ASTM G193 Corrosion Terms


Blowdown

The depressurizing of a natural gas pipeline to facilitate maintenance on the pipeline, accomplished by opening a valve and allowing the gas to escape to atmosphere, usually through a vertical pipe or “stack”.


Blushing

Whitening and loss of gloss of a coating, usually organic, caused by moisture (also know as blooming).

Source: NACE/ASTM G193 Corrosion Terms


Boiling point

The temperature at which a liquid changes into a gas.


Boilover

A condition that occurs during prolonged tank fires where heavier crude oils eventually heat up to a temperature of 400 to 500° F. The hot oil may circulate and come in contact with water in stratified layers or at the tank’s bottom. When this occurs, the water quickly expands to steam at a 1,700 to 1 volume increase. This usually causes a violent explosion which blows the tank’s contents upward causing a fireball and creating a wave of burning froth which can travel up to 20 miles per hour away from the tank.


Bond

A connection, usually metallic, that provides electrical continuity between structures that can conduct electricity.

Source: NACE SP0169


Bottle

A gas tight structure completely fabricated from pipe with integral drawn, forged end caps and tested in the manufacturer’s plant (per ASME guidelines).

Source: GPTC


Bottle-type holder

Any bottle or group of interconnected bottles buried underground installed in one location and used for the sole purpose of storing gas.

Source: GPTC


Bracelet anode

A galvanic anode with geometry suitable for direct attachment around the circumference of a pipeline.

Source: NACE/ASTM G193 Corrosion Terms


Branch service line

A distribution line that delivers gas to an end user, is considered a service line if it serves a single property, two adjacent properties, or an assembly containing multiple meters. If two properties are not adjacent, the pipe from the branch and upstream of that point becomes the main.


Breakout tank

A tank used to:

  1. relieve surges in an oil pipeline system, or
  2. receive and store oil transported by a pipeline for reinjection and continued transportation by pipeline.

as used in Introduction to Aboveground Storage Tanks WBT
Source: §194.5


Breakout tank

A tank used to:

  1. relieve pressure surges in a hazardous liquid pipeline system, or,
  2. receive and store hazardous liquid transported by a pipeline for reinjection and continued transportation by pipeline.

Source: §195.2


Brine

A strong solution of salt(s) with totally dissolved solid concentrations in the range from 40,000 to 300,000 or more parts per million (ppm) or milligrams per liter.


British thermal unit (BTU)

The quantity of heat required to raise the temperature of one pound of water 1°F under standard pressure. BTU values of gas indicate the amount of heat a given unit of gas will provide and helps to compare the heating values of different gases.


Brush-off blast cleaned surface

An abrasive blast cleaned steel surface that is free of all visible contaminants and foreign matter but may have some tightly adherent mill scale, rust, or coating.

Source: NACE/ASTM G193 Corrosion Terms


Buckle

A partial collapse of the pipe wall causing the pipe to flatten, become more oval or flatten due to excessive stresses associated with soil instability, landslides, washouts, frost heaves, earthquakes, etc. Buckles may be small, causing localized kinking or wall wrinkles, or global, involving several lengths of pipe that may buckle down, laterally, or vertically. Buckles cause localized stress concentrations and must not be installed in new construction. If found in existing systems, an analysis should be performed.


Bulge

A localized expansion or swelling of pipeline components beyond their specified diameter. Bulging may be caused by over pressurization or exceeding the specified yield strength of the material.


Buried

Covered or in contact with soil.

Source: §195.553


Business district

An area marked by a distinguishing characteristic of being used in the conducting of buying and selling commodities and service, and related transactions. A ‘business district’ would normally be associated with the assembly of people in shops, offices and the like in the conduct of such business.

Source: PHMSA interpretation PI-72-038


Bypass

Piping installed to provide an alternate flow path around various pieces of equipment which allows product to continue to flow while maintenance or other activities are performed.


Calcareous deposit/coating

A layer consisting of calcium carbonate and other salts deposited on the surface. When the surface is cathodically polarized as in cathodic protection, this layer is the result of the increased pH adjacent to the protected surface.

Source: NACE/ASTM G193 Corrosion Terms


Caliper pig

A mechanical device used to measure the internal diameter of a pipeline.


Cap pass

The final pass of the welding process.


Carbon dioxide

CO2 A fluid consisting of more than 90% carbon dioxide molecules compressed to a supercritical state.
A colorless, odorless gas that, when dissolved in water, forms carbonic acid which may be corrosive in a pipeline environment.

Source: §195.2


Carbon steel

By common custom, steel is considered to be carbon steel when

  1. no minimum content is specified or required for aluminum, boron, chromium, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium, zirconium, or any other element added to obtain a desired alloying effect; or
  2. the specified minimum content does not exceed 1.62% for manganese or 0.60% for copper.

All carbon steels may contain small quantities of unspecified residual elements unavoidably retained from raw materials. These elements (copper, nickel, molybdenum, chromium, etc.) are considered incidental and are not normally determined or reported.

Source: GPTC


Carbonate CO3

Naturally occurring ions in some oil field waters that participate in the buffering of acids and in the formation of scales. However, carbonates seldom contribute appreciably to the total dissolved solids in the water. Because no carbonate alkalinity exists in acidic environments (pH < 7.0), the CO3-2 ion concentrations within such solutions are zero.
May also be present as bicarbonate (HCO3).
Any of a group of minerals formed when combined with CO3.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Casing

A pipe designed and installed to surround and protect a pipeline from external stresses and damage.


Cast iron

An unqualified term that applies to gray cast iron which is a cast ferrous material in which a major part of the carbon content occurs as free carbon in the form of flakes interspersed through the metal. Because the carbon flakes do not bond with the ferrous material on the molecular level, the metal is brittle and susceptible to stress cracking under higher pressure situations.

Source: GPTC


Cathode

The electrode of an electrochemical cell at which reduction is the principal reaction. Electrons (current) flow toward the cathode in the external circuit.

Source: NACE SP0169


Cathode

The electrode of an electrochemical cell at which a reduction reaction occurs. Antonym: anode.
Reduction in this sense indicates an electrical potential that is becoming more negative. This indicates that this portion of the electrical circuit is gaining electrons and therefore referred to as reducing or a reduction reaction.

Source: NACE SP0169


Cathodic depolarization

The removal of cathodic hydrogen, which “depolarizes” the corrosion cell and greatly increases the corrosion rate at the anode. Removal of hydrogen at the cathode is identified as the rate-limiting reaction in steel corrosion and is a mechanism theorized for some bacterial acceleration of corrosion.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Cathodic disbondment

The destruction of adhesion between a coating and the coated surface caused by products of a cathodic reaction (usually hydrogen gas)

Source: NACE SP0169


Cathodic polarization

  1. The change of electrode potential caused by a cathodic current flowing across the electrode/electrolyte interface;
  2. forced active (negative) shift in electrode potential.

Source: NACE SP0169


Cathodic protection (CP)

A technique to control the corrosion of a metal surface by making the structure work as the cathode of an electrochemical cell.
(Typically, two types of CP systems are used: Galvanic systems use a series of sacrificial anodes of a more active metal (typically zinc or magnesium) to supply the current to the buried structure. Galvanic anodes continue to corrode, and need to be replaced periodically. Impressed current systems use anodes connected to a DC power source (rectifier – see ). Anodes are installed as a ground bed or deep well to provide the current flow to the buried structure.)

Source: NACE SP0169


Centering

The process of investigating and approximating a leak location by determining the perimeter of the migrating gas and locating the area that has the highest gas concentration.


Centrifugal compressor

Mechanical devices used to boost the pressure of the gas at key locations on transmission pipeline system. Centrifugal compressors are typically used in higher flow applications and impart the rotational energy provided by their prime movers to the gas to move it along within the pipeline.


Centrifugal pump

A mechanical device used to boost the pressure of fluids in a pipeline system. Centrifugal pumps contain a rotating impeller or rotating vanes mounted on a shaft rotated by an external power source, usually an electric motor or a natural gas powered engine. The rotating impeller uses centrifugal force to move fluids in a steady stream (without pulsation).


Centrifuge

A machine that uses centrifugal force to separate substances of varying densities, also called the shakeout or grindout machine. A centrifuge spins at high speeds, forcing the heavier substances to the bottom of a sample container. Centrifuges are commonly used to separate the water and sediment contained in crude oils.


Centrifuge test

A test to determine the amount of basic sediment and water (BS & W) in samples of oil or emulsion.


Chalking

The development of loose, removable powder (pigment) at the surface of an organic coating, usually caused by weathering.

Source: NACE/ASTM G193 Corrosion Terms


Check valve

A valve that permits fluid to flow freely in one direction and contains a mechanism to automatically prevent flow in the other direction

Source: §195.45


Checking

The development of slight breaks in a coating that do not penetrate to the underlying surface.

Source: NACE/ASTM G193 Corrosion Terms


Chemical injection

A method of applying corrosion inhibitors or biocides by continuous injection of chemical. Can be used in either stratified or annular flows. Generally recommended when the free liquids are transported in the gas stream. The term usually applies to the use of a high pressure pump and a chemical storage tank being located in the field.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Chemical treatment

Chemical treatments to pipeline facilities include the application of corrosion inhibitors, biocides, cleaning agents, descaling products, emulsion breakers, hydrate prevention chemicals (methanol) and other products.


Chiller

A chiller is generally a heat exchanger designed to remove thermal energy or heat from a gas flow stream.


City gate

A location at which gas may change ownership from one party to another (e.g., from a transmission company to a local distribution company), neither of which is the ultimate consumer. May also be referred to as a gate station or town border station.


Class 1 location

  1. An offshore area; or
  2. Any class location unit that has 10 or fewer building intended for human occupancy

Source: §192.5(b)(1)


Class 2 location

Any class location unit that has more than 10 but fewer than 46 building intended for human occupancy.

Source: §192.5(b)(2)


Class 3 location

  1. Any class location unit that has 46 or more buildings intended for human occupancy; or
  2. An area where the pipeline lies within 100 yards (91 meters) of either a building or a small, well-defined area (such as a playground, recreation are, outdoor theater, or other place of public assembly) that is occupied by 20 or more persons on at least 5 days a week for 10 weeks in any 12-month period. (the days and weeks need not be consecutive.)

Source: §192.5(b)(3)


Class 4 location

Any class location unit where buildings with four or more stories above ground are prevalent.

Source: §192.5(b)(4)


Class location unit

An onshore area that extends 220 yards (200 meters) on either side of the centerline of any continuous 1-mile (1.6 kilometers) of a pipeline.

Source: §192.5


Cleaning pig

A mechanical device run inside a pipeline that uses cups, scrapers, or brushes to remove dirt, paraffin, rust, mill scale, or other foreign matter from the inside of a pipeline. Cleaning pigs are run to increase the operating efficiency of a pipeline or to prepare the pipeline for an internal inspection. May be used in conjunction with cleaning fluids.


Close interval survey (CIS)

A potential survey with pipe-to-soil readings generally taken a maximum of two and one half (2 1/2) to five (5) feet apart.

Source: ANSI/NACE SP0502


Coalescence

The joining or fusing of metals produced by extreme temperatures achieved from an electrical arc between the metal electrode of a welding rod and the base metal of the pipe or other metallic structure. The welding machine produces the high electrical current and voltage necessary to get the arc to jump between the two metals.


Coating

A liquid, liquefiable or mastic composition that, after application to a surface, is converted into a solid protective, decorative or functional adherent film.


Coating

One layer of a coating applied in a single application.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Combustible gas indicator (CGI)

A device used to detect flammable gas concentrations. A 2 to 3 foot probe rod and hose assembly is normally attached to an electronic unit that draws in an air sample by squeezing a rubber bulb.


Combustion

The process of burning where a flammable substance is subjected to a heat source in the presence of oxygen. The degree of heat and the ratio of air to fuel will depend on the flammability characteristics of the substance.


Commercial blast cleaned surface

An abrasive blast cleaned steel surface that is free of all visible contaminants and foreign matter but may have some random staining on no more than 33 percent of the surface area.

Source: NACE/ASTM G193 Corrosion Terms


Commercially navigable waterway

A waterway where a substantial likelihood of commercial navigation exists.

Source: §195.45


Commingle

The mixing of gases or liquid products in a pipeline. With liquids, commingled products between batches in a pipeline are also referred to as “interface.”


Compartment

A flotation device used to keep the floating deck from becoming submerged. These compartments are found around the perimeter area of a floating deck.

as used in Introduction to Aboveground Storage Tanks WBT


Component

A component is considered any part of a pipeline that may be subjected to pump including, but not limited to, pipe, valves, fittings, flanges and closures.

Source: §195.2


Composite pipe repair

A non-metallic reinforcement of pipe using a variety of composite repairs. The reinforcements may include fiberglass, carbon fibers- and epoxies to provide hoop reinforcement to corrosion and mechanical damage. Varieties of composite repairs include Clockspring®, Armor Plate®- and Diamond Wrap®.


Compressed natural gas (CNG)

Natural gas stored inside containers at a pressure greater than atmospheric air pressure. CNG is normally placed in pressure-containing vessels (bottles) where it can be used as a portable fuel source (i.e., in CNG vehicles and other applications not attached to a pipeline).


Compressor station

Any combination of facilities which supplies the energy to move gas at increased pressure from production fields, in transmission lines, or into storage. Compressor stations are strategically placed along the pipeline to boost the pressure to maintain required pressures and flow rates. Typical components found at gas compressor stations include: piping manifolds, coolers, valves, reciprocating or centrifugal compressors, prime movers (electric motors, gas engines, gas turbines), local controls and instrumentation and may include liquid separation and collection facilities, as well as pigging facilities.


Computational pipeline monitoring (CPM)

A software-based monitoring tool that alerts the pipeline dispatcher of a possible pipeline operating abnormality that may indicate a commodity release or leak.

Source: §195.2


Conductivity

The ability of a substance (measured in ohm-cm) to conduct an electric charge or current due to the presence of positively or negatively charged ions.


Cone roof tank

A tank with a self-supporting external fixed (cone) roof with or without internal support columns.

as used in Introduction to Aboveground Storage Tanks WBT


Confirmatory direct assessment (CDA)

An integrity assessment method using more focused application of the principles and techniques of direct assessment to identify internal and external corrosion in a covered transmission pipeline segment.

Source: §192.903


Control piping

Pipe, valves and fittings used to interconnect air, gas, or hydraulically operated control apparatus.

Source: GPTC


Control room

An operations center staffed by personnel charged with the responsibility for remotely monitoring and controlling a pipeline facility.

Source: §192.3, §195.2


Control valve

A mechanical device used to vary flow rates and pressures on pipelines. Positioning signals are sent to the valve to achieve and maintain the desired set point. A control valve may be a globe, plug or ball-type valve. Its actuator may be pneumatic, hydraulic or electrically driven.


Controller

A qualified individual who remotely monitors and controls the safety-related operations of a pipeline facility via a SCADA system from a control room, and who has operational authority and accountability for the remote operations functions of the pipeline facility.

Source: §192.3, §195.5


Conversion of Service

A steel pipeline previously used in service not subject to this part

Source: §192.§14, §195.5


Corrosion

The deterioration of a material, usually a metal, that results from a reaction with its environment.

Source: NACE SP0169


Corrosion cell

A system consisting of an anode and a cathode immersed in an electrolyte, connected by a metallic path so as to create an electrical circuit. The anode and cathode may be different metals or dissimilar areas on the same metal surface; also called an electrochemical cell.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Corrosion concentration cell

An electrochemical cell, the electromotive force of which is caused by a difference in concentration of some component in the electrolyte (this difference leads to the formation of discrete cathodic and anodic regions).

Source: NACE/ASTM G193 Corrosion Terms


Corrosion control

Elimination or reduction of corrosion by applying mitigation methods and/or restricting potentially corrosive materials from entering the pipeline.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Corrosion fatigue

The process wherein a metal fractures prematurely under conditions of simultaneous corrosion and repeated cyclic loading at lower stress levels or fewer cycles than would be required to cause fatigue of that metal in the absence of the corrosive environment.

Source: NACE/ASTM G193 Corrosion Terms


Corrosion inhibitor

A chemical substance or combination of substances that, when present in the proper concentration and forms in the environment, reduces the corrosion rate.

Source: NACE/ASTM G193 Corrosion Terms


Corrosion product

A substance formed as a result of one or more corrosion reactions.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Corrosion rate

The rate at which corrosion proceeds.

Source: NACE SP0169


Corrosive

A substance having the capability or tendency to cause corrosion.

as used in Introduction to Part 192 WBT


Corrosive gas

A specific gas (such as CO2 or H2S) which has an internal corrosive effect on a specific pipeline transporting that gas.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Corrosive product

A corrosive material as defined by the DOT Hazmat Regulations (Title 49 CFR §173.136) means a liquid or solid that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact.

Source: §195.2, 29 CFR 1910.1200 App A


Coupon

A small, carefully weighed and measured specimen of metal that is used to determine metal loss caused by corrosion over a specified period of time.


Covered open-top floating roof tank

An existing open-top (external) floating roof tank that has been provided or equipped with a permanently attached cover (geodesic dome or similar weather protection) over the top of the tank.

as used in Introduction to Aboveground Storage Tanks WBT


Covered segment or covered pipeline segment

A segment of gas transmission pipeline located in a high consequence area

Source: §192.903


Covered task

An activity, identified by the operator, that:

  1. Is performed on a pipeline facility;
  2. Is an operations or maintenance task;
  3. Is performed as a requirement of this part; and
  4. Affects the operation or integrity of the pipeline.
    (Also known as the four-part test.)

Source: §192.801, §195.501


Cracks

Cracks in line pipe are separations in the molecular structure of the base metal and form as a result of improper manufacturing, construction, operational stresses or mechanical damage. Cracks are detrimental to the pipe’s pressure restraining capabilities and can propagate into complete failure or rupture zones.


Crevice corrosion

Localized corrosion of a metal or alloy surface at, or immediately adjacent to, an area that is shielded from full exposure to the environment because of close proximity of the metal or alloy to the surface of another material or an adjacent surface of the same metal or alloy.

Source: NACE/ASTM G193 Corrosion Terms


Criteria

Standards on which a judgment or decision is made. The standard is established by rule, test, standard, consensus, or other means.


Critical interference bond

An interference bond whose failure would jeopardize structural protection.
‘Critical bonds’ are metallic connections between adjacent buried structures that, if not connected, would allow detrimental corrosion to occur on one facility. The bond is only critical to the more negative pipeline facility, or the one losing current to the other facility.


Crude oil

The raw substance found in the earth that is a varying mixture of all the hydrocarbon atoms.


Curb valve

A valve installed for the purpose of shutting off the gas supply to a building. It is installed below grade in a service line at or near the property line and is operated by use of a removable key or specialized wrench. The valve is normally installed with a protective curb box or standpipe over or around it for quick subsurface access.

Source: GPTC


Current

The flow of electrons in a circuit, measured in amperes (amps).


Current attenuation survey

A method of measuring the overall condition of the coating on a pipeline based on the application of electromagnetic field propagation theory. Concomitant data collected may include depth, coating resistance and conductance, anomaly location, and anomaly type.

Source: ANSI/NACE SP0502


Current density

The current to or from a unit area of an electrode surface.

Source:


Customer meter

A device that measures gas delivered to a customer from consumption on its premises.

Source: §192.3


Customer piping

Piping owned by the customer.

Source: PHMSA interpretation PI-75-11


Customer regulator

A device that limits and maintains a set pressure to the customer. This pressure controlling device is normally installed just upstream of the customer meter.


Dead leg

A section of pipe in which no flow of gas or liquid occurs. Often this could be a branch connection that has been abandoned. Liquids and solids collect in dead legs and promoteinternal corrosion.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Deep anode (ground) bed

A ground bed in which the anodes are placed far below the earth’s surface in a single vertical hole. Deep ground beds are typically considered 50 feet or deeper.


Defect

An imperfection in a pressure vessel or pipe that, depending on the type of defect, should be analyzed using a recognized and approved procedure, such as ASME B31G or RSTRENG. Defects may need to be repaired or removed or the operating pressure lowered, depending on operating requirements of the facility.


Dehydration

The removal of water from hydrocarbons (gas or liquids) pumped from producing wells or the product stream.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Dent

Is a depression that produces a gross disturbance in the curvature of the pipe wall without reducing the pipe-wall thickness. The depth of a dent is measured as the gap between the lowest point of the dent and a prolongation of the original contour of the pipe.

Source: §192.309(b)


Design formula – liquids

Based on Barlow’s Equation, this formula is used to calculate the maximum design pressure of new pipe, and is determined in accordance with the following formula.
When used to calculate liquid pipeline design pressure, additional factors of E (seam joint factor determined in accordance with
§195.106(e) and F (standard design factor as found in
§195.106(a)), which make the final liquid design formula
P=(2ST/D) x E x F.

Source: §195.§106


Design formula for plastic – gas

P=(2S/SDR-1)(DF)
S= long term hydrostatic strength (or HDB),
SDR= standard dimension ration (outside diameter/wall thickness),
DF= Design factor

Source: §192.121


Design formula for steel – gas

Based on Barlow’s Equation, the formula is used to calculate the maximum design pressure of new pipe, and is determined in accordance with the following formula.
When used to calculate gas pipeline design pressures, additional factors of F(class design factor as found in §192.111), E (longitudinal joint factor as determined in §192.113) and T (temperature derating factor as found in §192.115) are used, which makes the final gas design formula P=(2St)/D) x F x E x T.

Source: §192.105 PHMSA interpretation 192.106(6), July 25, 1973


Destructive testing

A physical testing process (such as a burst or a tensile test) during which the specimen being tested is rendered unusable.


Determine

To establish or ascertain definitely after considering an investigation or calculation.
This is critical in differentiating between “discovering” vs. “determining” with respect to required time frames with which to file a “safety-related condition” report to the Office of Pipeline Safety (191.25 and195.56(a)). However, for integrity Management (§§192.933 and 195.452) there is no distinction between discovery and determination.

Source: §195.56(a), §192.933, §195.452


Dielectric coating

A coating that does not conduct electricity.

Source: NACE/ASTM G193 Corrosion Terms


Dike

The perimeter of an impounding space forming a barrier to prevent liquid from flowing in an unintended direction.

Source:


Diode

A bipolar semiconducting device having a low resistance in one direction and a high resistance in the other.

Source: NACE SP0169


Direct assessment (DA)

An integrity assessment method that utilizes a process to evaluate certain threats (i.e., external corrosion, internal corrosion and stress corrosion cracking) to a covered pipeline segment’s integrity. The process includes the gathering and integration of risk factor data, indirect examination or analysis to identify areas of suspected corrosion, direct examination of the pipeline in these areas, and post assessment evaluation.

Source: §192.903, §195.553


Direct current (DC)

An electrical current whose polarity or direction is constant with respect to time. DC current is typically used in impressed current cathodic protection systems. A rectifier is used to produce DC current.


Direct current voltage gradient (DCVG)

A method of measuring the change in electrical voltage gradient in the soil along and around a pipeline to locate coating holidays and characterize corrosion activity.

Source: ANSI/NACE SP0502


Direct examination

Inspections and measurements made on the pipe surface at excavations as part of external corrosion direct assessment (ECDA).

Source: ANSI/NACE SP0502


Direct sales lateral

A pipeline that transports gas directly from a transmission line to a large volume customer such as a factory or power plant. This pipeline is connected upstream from a distribution center or directly off of a transmission line.

Source: PHMSA interpretation PI 89-019


Disbonded coating

Any loss of adhesion between the protective coating and a pipe surface as a result of adhesive failure, chemical attack, mechanical damage, hydrogen concentrations, etc. Disbonded coating may or may not be associated with a coating holiday.

Source: ANSI/NACE SP0502


Disbondment

The loss of adhesion between a coating and the substrate (pipe surface).

Source: NACE/ASTM G193 Corrosion Terms


Discovery

To find, obtain knowledge or information, or become aware of a condition for the first time.
For IM, discovery is when an operator has adequate information about the condition to determine a potential threat (FAQ-58).


Dissimilar metals

Different metals that could form an anode-cathode relationship in an electrolyte when connected by and electron-conducting (usually metallic) path.

Source: NACE/ASTM G193 Corrosion Terms


Distributed anode bed

A ground bed where the anodes are spread over a wide geographical area. Usually employed to protect densely routed buried piping systems, such as in compressor station yards.


Distribution center

A location at which gas may change ownership from one party to another (e.g., from a transmission company to a local distribution company), neither of which is the ultimate consumer. May also be referred to as a gate station or town border station.

as used in Part 192 an Introduction WBT


Distribution line

A pipeline other than a gathering or transmission line. A pipeline that carries or controls the supply of natural gas from a town border or city gate and moves the gas to the customer.
(A distribution line is a network of piping downstream of a distribution center used to supply gas to its customers. In practical terms, the distribution piping ends at the customer’s regulator and/or meter.)

Source: §192.3


Dome roof tank

A modification of the cone-roof tank. In the dome-roof tank, the roof plates are usually formed with spherically curved segments joined to be self-supporting. Steel dome roofs are usually made of rectangular steel plate and should not be confused with geodesic aluminum domes which are designed to API-650 Standard, Appendix G and are constructed of aluminum.

as used in Introduction to Aboveground Storage Tanks WBT


Double submerged arc weld (DSAW)

A pipe having longitudinal or spiral butt joints produced by at least two weld passes, including at least one each on the inside and outside of the pipe. Coalescence is produced by heating with an electric arc or arcs between the bare metal electrode or electrodes and the work. The welding molten metal is shielded by a blanket of granular, fusible material on the work that is used to reduce the impurities (slag) introduced from the surrounding air. Pressure is not used and filler metal for the inside and outside welds is obtained from the electrode(s).

Source: GPTC


Down-hole log

Inspection of casing or tubing in wells using electromagnetic, ultrasonic or other technologies to locate corrosion or other wall loss features in the pipe. (see Inline Inspection (ILI)).

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Downstream

The direction in which the fluid is moving with regard to a reference point. With compressor and pump stations, downstream would be the discharge side of the facility.


Drip type odorizer

Equipment for introducing odorant from a storage tank directly into a gas stream through a gravity flow system. The odorant may be regulated by the orifice float valves or rotameters.


Drip, pipeline drip, drip leg

A vessel attached beneath a gas pipeline in which water and liquids accumulate due to gravity. The drip liquids must be manually blown into a tank in order for the drip to continue functioning properly. Solids often accumulate in drip vessels since there is typically no means to remove solids.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Dry film thickness

The thickness of a dried film, coating, or membrane.

Source: NACE/ASTM G193 Corrosion Terms


Dry gas

Gas above its dew point and without condensed liquids,
For most operator established tariff purposes, any gas containing water vapor less than 7 pounds per million cubic feet (mmcf) is considered dry gas.

Source: GPTC


Ductile (nodular) iron

A cast ferrous material in which the free graphite (carbon) present is in a spherical form rather than a flake form as in cast iron. These round shaped carbon elements cause ductile iron to be more malleable than cast iron, yet retain its toughness. These desirable properties of ductile iron are achieved by means of chemistry and a specialized heat treatment of the castings.

Source: GPTC


ECDA Region

A section or sections of a pipeline that have similar physical characteristics and operating history and in which the same indirect inspection tools are used.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT
Source: NACE RP0502-2002


Elbow (ELL)

A pipe fitting that makes an angle in a pipe run. Unless stated otherwise, the angle is usually assumed to be 90°. In larger pipelines, fitting type elbows may not be recommended due to their abrupt change in direction. Piggable lines should be equipped with bends of a minimum bend ratio of 1 1/2D, but the actual radius depends on the type of pig.


Electric flash welded pipe

Pipe having a longitudinal butt joint wherein coalescence is produced simultaneously over the entire area of butting surfaces by the heat obtained from resistance to the flow of electric current between the two surfaces, and by the application of pressure after heating is substantially completed. Flashing and upsetting are accompanied by the expulsion of metal from the joint.

Source: GPTC


Electric fusion welded pipe

Pipe having a longitudinal butt joint wherein coalescence is produced in the preformed tube by manual or automatic electric-arc welding. The weld may be single or double and may be made with or without the use of filler metal.

Source: GPTC


Electric resistance welded (ERW) pipe

Pipe which has a longitudinal butt joint wherein coalescence is produced by the application of pressure and by the heat obtained from the resistance of the pipe to the flow of an electric current in a circuit of which the pipe is a part.

Source: GPTC


Electrical isolation

The condition of being electrically separated from other metallic structures or the environment.

Source: NACE SP0169


Electrical resistance probes

An electronic probe that can be used in systems where gas or liquids (including hydrocarbons) are present to determine metal loss over time by measuring the increase in the resistance of the electrode as its cross-sectional area is reduced by corrosion. The resistance of the electrode is then compared with the resistance of a reference electrode.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Electrical survey

A series of closely spaced pipe-to-soil readings over pipelines which are subsequently analyzed to identify locations where a corrosive current is leaving the pipe.

Source: §192.3, §195.553


Electrochemical impedance spectroscopy (EIS)

An AC electrochemical measurement technique. The technique measures the electrical response of the metal/solution interface over a range of frequencies, typically 1 mHz to 10 kHz.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Electrochemical noise (ECN)

Measures naturally occurring fluctuations of potential or current. It also can measure current noise under an applied potential, or measure potential noise under an applied current. Current noise is a measurement of current fluctuations between two nominally identical electrodes. Potential noise is a measurement of the potential fluctuations between one electrode and a reference electrode, or between two nominally identical electrodes. The frequency of these fluctuations is typically below 1 Hz.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Electrode

An electronic conductor used to establish electrical contact with an electrolyte as part of a cathodic protection circuit.


Electrolysis

Production of chemical changes of the electrolyte by the current flowing through an electrochemical cell.

Source: NACE/ASTM G193 Corrosion Terms


Electrolyte

A chemical substance containing ions that migrate in an electric field. Electrolytes can play a role in external corrosion or internal corrosion of metallic pipelines.  For external corrosion,  electrolyte refers to the soil or liquid adjacent to and in contact with a buried or submerged piping system, including the moisture and other chemicals contained therein. For internal corrosion, electrolyte refers to the chemicals contained in water on the inside the pipeline, including solutions of salts, acids and bases.

Source: GPTC


Electrolyte

A chemical substance containing ions that migrate in an electric field. In relationship to storage tanks, electrolyte refers to the soil or liquid adjacent to and in contact with the bottom of the tank, including the moisture and other chemicals contained therein.

as used in Introduction to Aboveground Storage Tanks WBT


Electrolytically shorted/coupled casing

A casing with a low casing-to-pipe resistance due to the presence of an electrolyte in the casing/pipe annulus. Electrolytically shorted or coupled casings may be shorted periodically and not continuously. These casing are not considered to be metallically shorted.


Electromagnetic inspection technique

An aboveground survey technique used to locate coating defects on buried pipelines by measuring changes in the magnetic field that are caused by the defects.

Source: ANSI/NACE SP0502


Electromotive force series (EMF series)

A list of elements arranged according to their standard electrode potentials, the sign being positive for elements whose potentials are more noble than hydrogen such as gold and negative for those more active than hydrogen such as zinc (not to be confused with galvanic series).

Source: NACE/ASTM G193 Corrosion Terms


Electronic probes

A broad term covering corrosion measurement devices typically installed in pipelines to provide on-line data. Probe types include electrical resistance (ER), linear polarization resistance (LPR) and many other types.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Emergency flow restricting device

A check valve or remote control valve.

Source: §195.45


Emergency response personnel

Any persons engaged in the response to an emergency, including firefighters, police, civil defense/emergency management officials, sheriffs, military and manufacturing and transportation personnel.


Emergency shutdown system (ESD)

An automated system designed to shut the station or facility down, or change to a reduced operational state in the event of a failure or hazardous situation.
Specific requirements for gas compressor stations can be found in §192.167.


Emergency valve

For gas transmission operations, an emergency valve is any valve that might be required during any emergency.
For gas distribution operations, an emergency valve is any valve which may be necessary for the safe operation of a distribution system.

Source: §192.745, §192.747


Environment

The surroundings or conditions (physical, chemical, mechanical) in which a material exists.

Source: NACE/ASTM G193 Corrosion Terms


Environmentally sensitive area

An area of environmental importance which is in or adjacent to navigable waters.

Source: §194.5


Erosion

Abrasive metal loss caused by high surface velocity of the transported media, particularly when entrained solids or particulates are present.


Erosion corrosion

A conjoint action involving erosion and corrosion in the presence of a moving corrosive fluid or a material moving through the fluid, leading to accelerated loss of material.

Source: NACE/ASTM G193 Corrosion Terms


Evaluation (for Operator Qualification (OQ))

A process, established and documented by the operator, to determine an individual’s ability to perform a covered task by any of the following:

  1. Written examination;
  2. Oral examination;
  3. Work performance history review;
  4. Observation during (1) performance on the job, (2) on the job training, or (3) simulations; or
  5. Other forms of assessment

Source: §192.803, §195.503


Excavation activities

Excavation, blasting, boring, tunneling, backfilling, the removal of above ground structures by either explosive or mechanical means, and other earth moving operations.

Source: §192.6§14, §195.442


Excavation damage

Any impact that results in the need to repair or replace an underground facility due to a weakening, or the partial or complete destruction, of the facility, including, but not limited to, the protective coating, lateral support, cathodic protection, or the housing for the line device or facility.

Source: §192.1001


Excess flow valve (EFV)

A device that is installed in a gas pipeline or service line to automatically restrict or shut off the gas flow through the line when the flow exceeds a predetermined limit.

Source: GPTC


Explosive

To undergo a rapid chemical reaction with the production of noise, heat, and violent expansion of gases, or to burst violently as a result of pressure.

Source: Webster’s


Exposed pipeline

Any part of a pipeline not completely buried, and partially exposed to the atmosphere.


Exposed underwater pipeline

An underwater pipeline where the top of the pipe protrudes above the underwater natural bottom (as determined by recognized and generally accepted practices) in waters less than 15 feet (4.6 meters) deep, as measured from mean low water.

Source: §192.3, §195.2, §195.413


External corrosion direct assessment (ECDA)

A four-step process that combines pre-assessment, indirect inspection, direct examination, and post-assessment to evaluate the threat of external corrosion to the integrity of a pipeline.

Source: §192.925, §195.553


External floating roof tank

A tank with an uncovered roof that floats on the surface of the liquid contained inside the tank (except when empty).

as used in Introduction to Aboveground Storage Tanks WBT


Facultative anaerobic bacteria

Bacteria that are able to carry out both aerobic and anaerobic metabolism and therefore are able to grow and reproduce in both the presence and absence of oxygen.

Source: NACE TM0194 Internal Corrosion


Fail-safe

A design feature which will maintain or result in a safe condition in the event of malfunction or failure of a power supply, component, or control device. Fail-safe may occur by three methods: fail open, fail close, or fail at last position.

Source: §193.2007


Failure

A general term used to imply that a part in service has become completely inoperable; is still operable but is incapable of satisfactorily performing its intended function; or has deteriorated seriously, to the point that is has become unreliable or unsafe for continued use.

Source: ASME B31.8S 2004


Far-ground (FG) potential

A structure-to-electrolyte potential measured directly over the pipeline, away from the electrical connection to the pipeline.

Source: ANSI/NACE SP0502


Farm tap

A low volume service connection, generally off a high-pressure transmission line, providing gas to a customer in a rural location often provided as part of a right-of-way (ROW) agreement.


Fault

Any anomaly in the coating, including disbonded areas and holidays.

Source: ANSI/NACE SP0502


Fault current

A current that flows from one conductor to ground or to another conductor as a result of an abnormal connection (including and arc) between the two. A fault current flowing to ground may be called a ground fault current.

Source: NACE/ASTM G193 Corrosion Terms


Federal Energy Regulatory Commission (FERC)

An independent Federal agency that regulates the interstate transmission of electricity, natural gas and oil. FERC also reviews proposals to build liquefied natural gas (LNG) terminals and interstate natural gas pipelines as well as licensing hydropower projects.

as used in Regulatory Overview WBT


Field signature method

Electrical field mapping is achieved by measuring local variations in voltage from an induced current applied directly to a pipe or structure to monitor changes due to the effect of internal or external cracking, pitting, corrosion, or erosion in the measurement area. The induced current is fed into the pipe, typically 3 to 10 m (9 to 30 ft) apart for a large pipe or a few centimeters or inches for small pipes to provide uniform current distribution. Welded, glued or spring-loaded contact pins make electrical connections externally. The voltage readings are monitored and compared with one another to look at any non-uniformity that could be due to cracking or pitting in the monitored section.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Filler pass

The third and subsequent passes of welding with the purpose of filling the joint with metal. Filler passes follow the stringer and hot passes and precede the cap weld.


Filliform corrosion

Corrosion that occurs under some coatings in the form of randomly distributed threadlike filaments.

Source: NACE/ASTM G193 Corrosion Terms


Fire surface area

The approximate surface area inside a round storage tank that is determined by using the formula diameter squared, times 0.8 (D2 x 0.8). This equation is used to calculate the amount of fire suppressant foam needed to extinguish tank fires. It can also be used to estimate the amount of water or snow a tank roof might be supporting.

Source:


Fitting

A part used in a piping system, for changing direction, branching or for change of pipe diameter, and which is mechanically joined to the system.


Fixture

Devices or components which transfer the load from the pipe or structural attachment to the supporting structure or equipment. They include hanging type fixtures such as hanger rods, spring hangers, sway braces, counterweights, turnbuckles, struts, chains, guides and anchors and bearing type fixtures such as saddles, bases, rollers, brackets and sliding supports.


Flame ionization

A device used to detect flammable gas concentrations. Sample vapors are drawn in and subjected to a high-temperature filament where the gases are ionized to indicate the concentration of combustible gases.


Flammable

A substance that will burn readily or quickly. OSHA defines flammable substances as those materials that have the ability to generate ignitable vapors (also referred to as the material’s flash point) with temperatures at or below 100°F.


Flammable (explosive) limit

The range of a gas or vapor concentration that will burn or explode if an ignition source is introduced. Limiting concentrations are commonly called the “lower explosive or flammable limit” (LEL/LFL) and the “upper explosive or flammable limit” (UEL/UFL). Below the explosive or flammable limit, the mixture of product in air is too lean to burn, and above the upper explosive or flammable limit, the mixture is too rich to burn.


Flammable liquid

A liquid having a flash point of not more than 60.5º C (141º F) or any material in a liquid phase with a flash point at or above 37.8 ºC (100º F).

Source: 49 CFR, §173.130


Flammable product

A “flammable liquid” as defined by §173.130 Class 3 – Definitions of this chapter.

Source: §195.2


Flaring

The venting and igniting of flammable vapors or gas from a pipeline.


Floating roof

A storage tank covering that rests on the surface of a hydrocarbon liquid in the tank and rises and falls with the liquid level. The use of a floating roof eliminates the vapor space above the liquid which could allow for air to mix with the oil or refined product and create a fire hazard. The floating roof also conserves the lighter hydrocarbon atoms that might otherwise evaporate out of the liquid. Floating roofs can also be found on tanks with solid roofs for the same purposes. In these instances, the floating roof is referred to as an “internal floating roof.”


Floating roof tank

Any aboveground, vertical atmospheric storage vessel with an internal or external floating roof. The floating-roof tank is designed to minimize filling and breathing losses by eliminating or minimizing the vapor space above the stored liquid.

as used in Introduction to Aboveground Storage Tanks WBT


Flow line

A smaller pipe run within a gathering lease that connects a flowing well to a storage tank. These lines typically have little if any pressure in them as the liquids travel to the lease tank. These lines are considered unregulated by PHMSA since they are part of the gathering system.


Fluid

A substance (as a liquid or gas) capable of flowing or conforming to the outline of its container that easily yields to pressure.


Foreign structure

Any metallic structure that is not intended as a part of a system under CP.


Frangible joint

A continuous fillet weld between the roof plates and the top angle that does not exceed 3/16 inch (5 mm). Properly designed, this roof-to-shell joint may be considered frangible in the event of excessive internal pressure. This joint is designed to fail before a failure occurs in the tank-shell joints or the shell-to-bottom joint.

as used in Introduction to Aboveground Storage Tanks WBT


Fretting corrosion

Deterioration at the interface between contacting surfaces as the result of corrosion and slight oscillatory slip between the two surfaces.

Source: NACE/ASTM G193 Corrosion Terms


Frictional loss

The loss of fluid pressure (head) experienced when fluid flows through a pipeline. The amount of friction loss depends upon viscosity of the fluid, velocity of the fluid, roughness of the pipe’s interior wall surface, size of the pipe, and the length of the pipeline.


Frothover

The continuous burping and frothing of a tank’s contents over the side as a result of a tank fire. Frothover happens when the tank product contains water that comes into contact with hot oil.


Furnace lap welded pipe

Pipe which has a longitudinal lap joint that is produced by the forge welding process. In this process, coalescence is produced by heating a preformed tube to welding temperature and then passing it over a mandrel. The mandrel is located between the two welding rolls that compress and weld the overlapping edges.

Source: GPTC


Fusion

A process of joining plastic pipe segments by melting the plastic polymers at the two ends with heat to an extent where they will molecularly bond when pressed together. Depending on the type and size of pipe and the fusion machine used, precise temperatures, pressures, and time of cooling prior to releasing the joint from the fusion machine are all critical to producing an acceptable joint.


Galvanic

Pertaining to the current resulting from the coupling of dissimilar electrodes in an electrolyte.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Galvanic anode

A metal that provides sacrificial protection to another metal that is more noble when electrically coupled in an electrolyte. This type of anode is the electron source in one type of cathodic protection.

Source: NACE SP0169


Galvanic cell

An anode, cathode, metallic connection, and electolyte.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Galvanic corrosion

Accelerated corrosion of a metal because of an electrical contact with a more noble metal or non-metallic conductor in a corrosive electrolyte.

Source: NACE/ASTM G193 Corrosion Terms


Galvanic couple

A pair of dissimilar conductors, commonly metals, in electrical contact in an electrolyte.

Source: NACE/ASTM G193 Corrosion Terms


Galvanic series

A list of metals and alloys arranged according to their relative electrolytic potentials to one another in a given environment. The metals or alloys higher on the list (more negative) are anodic to those lower on the list and the metals or alloys lower on the list (more positive) are cathodic to those higher on the list.


Gas

Gas is considered natural gas, flammable gas, or gas which is toxic or corrosive.
This includes natural gas and other gases like propane, hydrogen and hydrogen sulfide. and also include carbon dioxide (CO2) if is transported in a gaseous state. This defintion does not include gases such as helium, oxygen or nitrogen since these are not flammable, toxic or corrosive. In general, gas refers to a fluid in the vapor state of a substance.

Source: §192.3
as used in Regulatory Overview WBT


Gate station

A location at which gas may change ownership from one party to another (e.g., from a transmission company to a local distribution company), neither of which is the ultimate consumer. In this instance, the gas is purchased for the sole purpose of resale. A gate station is also referred to as city gate station or town border station.


Gate valve

A valve in which a thick slab of metal with a hole in the bottom half slides between two sealing elements. When the slab is in the upper position, the hole aligns with the valve body ports and allows flow.


Gathering line – type A (gas)

Metallic pipe operating at a hoop stress of 20% or more of SMYS, and non-metallic pipe with a MAOP of more than 125 psig, and is located in a Class 2, 3, or 4 location.

Source: §192.8


Gathering line – type B (gas)

Metallic pipe operating at a hoop stress of less than 20% SMYS, and non-metallic pipe with a MAOP of 125 psig, or less, and is located in a Class 3 or 4 location, or an area within a Class 2 location as determined by one of the methods:

  1. Class 2 location,
  2. An area extending 150 feet (45.7 m) on each side of the centerline of any continuous 1 mile (1.6 km) of pipeline and including more than 10 but fewer than 46 dwellings or
  3. An area extending 150 feet (45.7 m) on each side of the centerline of any continuous 1000 feet (305 m) of pipeline and including 5 or more dwellings.

Source: §192.8


Gathering line – (gas)

A gathering line is a pipeline that transports gas from a current production facility to a transmission line or main.
Gathering lines have limited jurisdiction by the Office of Pipeline Safety. Additional information regarding jurisdiction can be found in §192.8.

Source: §192.3


Gathering line (hazardous liquid)

A pipeline 219.1 mm (8 5/8 in) or less nominal outside diameter that transports petroleum from a production facility.
(Gathering lines have limited jurisdiction by the Office of Pipeline Safety. Additional information regarding jurisdiction can be found in §195.11.)

Source: §195.2


Gauging

The process of conducting certain measurement-related tests to crude oil or other refined products in the field. When used in conjunction with storage tanks, it uses a specialized instrument to determine the liquid level of a tank.


Gauging hatch

The small door opening in a tank lid or other vessel through which measuring and sampling are performed.


Gauging pig (gauging plate)

A tool inserted into a pipeline to determine the largest internal diameter restriction. The plate only provides information on the largest restriction, but gives no information as to the number of restrictions, or their location along the pipeline.


Gauging table

Volumetric tables prepared by engineers to calculate the number of barrels or cubic meters for any given depth of liquid in a tank. They are sometimes called strapping tables. Gauging or strapping tables are specific to only one tank and account for individual differences in internal components and other volume affecting factors.


General corrosion

Corrosion pitting so closely grouped as to affect the overall strength of the pipe is considered general corrosion.

Source: §192.485(a)
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Geodesic dome

A self-supporting roof assembly that is constructed of aluminum panels. This roof is attached to and supported by the tank at mounting points equally spaced around the perimeter of the tank.

as used in Introduction to Aboveground Storage Tanks WBT


Geographic information system (GIS)

A system of computer software, hardware, data, and personnel to help manipulate, analyze, and present information that is tied to a geographic location.

Source: ASME B31.8S 2004


Geometry (geo) pig

Any of a variety of in line tools designed to measure the internal geometry and configuration of a pipeline, including dents, ovality and wrinkles, bend radius and angle and changes in wall thickness.


Geophone

A geophone is an acoustical monitoring device that is used to magnify sounds in and around pipelines. Geophones are typically used to monitor the passage of pipeline pigs or to detect leaks.


Girth weld

A complete circumferential weld joining pipe end-to-end, also called a butt weld. An actual girth weld is usually made up of a number of weld passes beginning with the root pass or stringer bead and completed with the cap pass. Girth welds are made according to an operator’s welding procedure.


Globe valve

A valve internally equipped with a flat or conical plug attached to a stem that blocks flow when it is seated in a circular orifice. The body of the valve is normally spherical in shape with a lateral incoming flow-path being directed vertically through the closure seat, then exiting again laterally. This radical change in flow-path causes the characteristic attribute of a comparatively large pressure drop across this type of valve. Throttling or total shut-off is obtained by adjusting the plug downward against the flow-path toward the mating seat. Globe valves are most typically used in a process plant environment.


Graphitic corrosion

Deterioration of cast iron wherein the metallic constituents are selectively leached or converted to corrosion products, leaving the graphitic particles intact. (Should not be used to describe graphitization.)

Source: NACE/ASTM G193 Corrosion Terms


Graphitization

The formation of graphite in iron or steel, usually from decomposition of iron carbide at elevated temperatures.
(Should not be used to describe graphitic corrosion.)

Source: NACE/ASTM G193 Corrosion Terms


Grit blasting

Abrasive blast cleaning using grit as the abrasive.

Source: NACE/ASTM G193 Corrosion Terms


Ground temperature

The temperature of the earth at pipe depth.


Grounding

An electrical term indicating two conductive components have been made electrically neutral. There is no difference in electrical potential between the two components when they are “grounded.”
In many cases the two components are the tank and the earth it rests on. The two components could also be the tank and its floating roof, attached electric devices such as pump motors, and lighting equipment. In the case of electrical equipment attached to the tank, “grounding” simply means the components are connected so that no electrical energy from the attached component can energize the tank body.

as used in Introduction to Aboveground Storage Tanks WBT


Gulf of Mexico and its Inlets

The waters from the mean high water mark of the coast of the Gulf of Mexico and its inlets open to the sea (excluding rivers, tidal marshes, lakes, and canals) seaward to include the territorial sea and Outer Continental Shelf to a depth of 15 feet (4.6 meters), as measured from the mean low water.

Source: §192.3, §195.2


Half-cell (electrode)

A device that contains a conductive electrode immersed in a surrounding conductive electrolyte and used to measure the effectiveness of cathodic protection systems. A half cell may be made of a variety of materials, but typically is a copper-copper sulfate for soil readings, or a silver-silver chloride for readings taken in a saline environment.


Hand tool cleaning

Removal of loose rust, loose mill scale, and loose coating by hand chipping, scraping, sanding, and wire brushing.

Source: NACE/ASTM G193 Corrosion Terms


Hazard to navigation

A pipeline where the top of the pipe is less than 12 inches (305 millimeters) below the underwater natural bottom (as determined by recognized and generally accepted practices) in water less than 15 feet (4.6 meters) deep, as measured from the mean low water.

Source: §192.3, §195.2


Hazardous leak

A leak that represents an existing or probable hazard to persons or property and requires immediate repair or continuous action until the conditions are no longer hazardous.

Source: §192.1001


Hazardous liquid

Means petroleum, petroleum products, or anhydrous ammonia.
(Petroleum products include unleaded gasoline, jet fuel, heating oil and anhydrous ammonia. Propane, butane and CO2 that are transported in a liquid state are also considered hazardous liquids.)

Source: §195.2


Hearing

An informal conference or a proceeding for oral presentation. Unless otherwise specifically prescribed in this part (190), the use of “hearing” is not intended to require a hearing on the record in accordance with section 554 of title 4, U.S.C.

Source: §190.3


Helium

A colorless, odorless inert gas occurring in natural gas and with radioactive ores. It is used as a component of artificial atmospheres and laser media, as a refrigerant, as a lifting gas for balloons and as a superfluid in cryogenic research. Atomic number 2; atomic weight 4.0026; boiling point -268.9°C; density at 0°C 0.1785 gram per liter.

as used in Introduction to Part 192 WBT


High consequence area (HCA) – Gas

An area defined by certain Class locations or a potential impact radius that must be covered by an gas operator’s integrity management program (see §192.903 for a complete definition)

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


High consequence areas (HCAs) – hazardous liquids

Regions of the United States where the consequences of a hazardous liquid leak or spill could be significant. This includes unusually sensitive areas of the environment (defined in 195.6), high population areas (urbanized areas identified by the Census Bureau), other populated areas (other areas of concentrated population defined by the Census Bureau), and commercially navigable waterways (see §195.450 for a complete definition).

Source: IM Website – glossary


High consequence area (HCA) – hazardous liquid

A commercially navigable waterway, high population area, other populated area, or an unusually sensitive area.

Source: §195.45


High level alarm

A point established in the operators control system that identifies when the process condition has reached a high limit. In tank level alarm schemes, this would typically be a limit set near the upper 25% of the tank level.

Source: §195.446(e), API RP 2350 and NFPA 30
as used in Introduction to Aboveground Storage Tanks WBT


High population area

An urbanized area, as defined and delineated by the Census Bureau, that contains 50,000 or more people and has a population density of at least 1,000 people per square mile.

Source: §195.45


High pressure distribution system

A distribution system in which the gas pressure in the main is higher than the pressure provided to the customer.

Source: §192.3


High volume area

An area which an oil pipeline having a nominal outside diameter of 20 inches (508 millimeters) or more crosses a major river or other navigable waters, which, because of the velocity of the river flow and vessel traffic on the river, would require a more rapid response in case of a worst case discharge or substantial threat of such a discharge. Appendix B to this part (194) contains a list of some of the high volume areas in the United States.

Source: §194.5


Highly volatile liquid (HVL)

A hazardous liquid which will form a vapor cloud when released to the atmosphere and which has a vapor pressure exceeding 276kPa (40psia) at 37.8 deg C (100 deg F).

Source: §195.2


Holiday

A discontinuity in a protective coating that exposes unprotected surface to the environment.

Source: ANSI/NACE SP0502


Holiday detection

Testing a coating for holidays by using an instrument that applies a voltage between the external surface of the coating and the pipe.

Source: GPTC


Hoop stress

The stress in a pipe wall acting circumferentially in a plane perpendicular to the longitudinal axis of the pipe and produced by the pressure of the fluid or gas in the pipe. Hoop stress is a very critical factor in determining a pipe’s pressure holding capabilities and thus its appropriate application. Hoop stress is calculated using Barlow’s Equation (see Barlow”s Equation).

Source: GPTC


Hot pass

The second pass made on a weld. The hot pass immediately follows the root or stringer bead pass and precedes the filler passes and cap weld.


Hot tap

Branch piping connections made to operating pipelines, mains, or other facilities while they are in operation. The branch piping is connected to the operating line, and the operating line is tapped while it is under gas pressure.

Source: B31.8 2003
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Housekeeping

Keeping a work location free of debris and hazards that could contribute to accidents.


Human occupancy

A building used for a purpose involving the presence of humans

Source: PHMSA interpretation PI-77-017


Hydraulic gradient

Graphical relationship between pipeline pressure (head) and elevation along a pipeline. If the hydraulic gradient is plotted in feet of liquid or head against a profile illustrating elevation and distances between the discharge of one station and the suction at another station down the pipeline, it describes the pressure conditions along this particular line segment. The amount of slope of the plotted gradient is based upon the fluid’s frictional losses between stations.


Hydraulic head

The force exerted by a column of fluid expressed by the height of the fluid above the point at which pressure is measured. Although head refers to distance or height, it is used to express pressure, since the force of the fluid column is directly proportional to its height (also called head or hydrostatic head).


Hydrocarbon (HC) filter

A filtering element used to separate out heavier hydrocarbons when using a combustible gas indicator (CGI). Gasoline, propane, butane and commercial solvents are examples of heavier hydrocarbons.


Hydrogen

A colorless, highly flammable gas, hydrogen is the lightest of all gases and the most abundant element in the universe. It is used in the production of synthetic ammonia and methanol, in petroleum refining, in the hydrogenation of organic materials, as a reducing atmosphere, in oxyhydrogen torches and in rocket fuels. Atomic number 1; atomic weight 1.00794; melting point -259.14°C; boiling point -252.8°C; density at 0°C 0.08987 gram per liter; valence 1.

as used in Introduction to Part 192 WBT


Hydrogen blistering

The formation of subsurface planar cavities, called hydrogen blisters, in a metal resulting from excessive internal hydrogen pressure. Growth of near-surface blisters in low-strength metals usually results in surface bulges.

Source: NACE/ASTM G193 Corrosion Terms


Hydrogen embrittlement

Embrittlement caused by the presence of hydrogen within a metal or alloy.

Source: NACE/ASTM G193 Corrosion Terms


Hydrogen induced cracking

Stepwise internal cracks that connect adjacent hydrogen blisters on different planes in the metal, or to the metal surface.

Source: NACE/ASTM G193 Corrosion Terms


Hydrogen stress cracking

Cracking of a metal or alloy under the combined action of tensile stress and the presence of hydrogen in the metal or alloy.

Source: NACE/ASTM G193 Corrosion Terms


Hydrogen sulfide (H2S)

A colorless, poisonous, and flammable gas that has a characteristic rotten egg odor at low concentrations. Hydrogen sulfide is very soluble in water and when dissolved, it behaves as a weak acid and usually causes pitting of carbon steel, depending on the type of film formed on the metal surface. H2S is very reactive with substances it contacts.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Hydrometer

An instrument used to determine the specific gravity of liquids.


Hydrostatic pressure

The force exerted by a body of fluid at rest; it increases directly with the density and the depth of the fluid and is expressed in psi or kPa. The hydrostatic pressure of fresh water is 0.433 psi per foot of depth (9.792 kPa/m). In drilling, the term refers to the pressure exerted by the column drilling fluid in the well bore. In a water-driven reservoir, the term refers to the pressure that may furnish the primary energy for production.


Hydrostatic test (hydrotest)

Proof testing of sections of a pipeline by filling the line with water and pressurizing it until the nominal hoop stresses in the pipe reach a specified value.

Source: NACE RP0502


Ignition temperature

The minimum temperature required to ignite gas or vapor without a spark or flame being present.


ILI or Inline inspection

The inspection of a steel pipeline using an electronic instrument or tool that travels along the interior of the pipeline in order to locate corrosion and/or material defects.

Source: NACE
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


ILI tools

Any of a variety of inspection devices designed to be run while the pipeline remains in service. These devices, or “pigs”, measure and record the internal geometry, external or internal corrosion as well as provide information about pipe characteristics such as wall thickness and other pipe defects. Magnetic flux leakage, ultrasonic, calipers, and geometry are examples of smart tools; also referred to as smart pigs.


Impressed current

An electric current supplied by a device employing a power source that is external to the electrode system.

Source: NACE/ASTM G193 Corrosion Terms


Impressed current anode

Anodes, typically made of graphite, carbon or high-silicon cast iron installed in either ground beds or deep wells drilled along the pipeline route, that provide sacrificial protection to another metal when electrically connected to a rectifier.


Inactive pipeline

A pipeline that is not presently being used to transport gas or liquids, but continues to be maintained under Part 192 or 195.
May also be called an idle pipeline.
(The Parts 192 and 195 regulations do not define “idle” pipe. Pipe is considered either active or abandoned.)

Source: GPTC


Incident

  1. An event that involves a release of gas from a pipeline, or of a liquefied natural gas, liquefied petroleum gas, refrigerant gas, or gas from an LNG facility, and the results in one or more of the following consequences:
    1. A death, or personal injury necessitating in-patient hospitalization;
    2. Estimated property damage of $50,000 or more, including loss to the operator and others, or both, but excluding the cost of gas lost;
    3. Unintentional estimated gas loss of three million cubic feet or more;
  2. An event that results in an emergency shutdown of an LNG facility. Activation of an emergency shutdown system for reasons other than an actual emergency does not constitute an incident.
  3. An event that is significant in the judgment of the operator, even though it did not meet the criteria of paragraphs (1) or (2) of this definition.

Source: §191.3


Incident Command System (ICS)

An emergency management system, most commonly used for large emergencies, whereby key decisions are made by a unified command group consisting of representatives of both the Federal and State Government and the responsible party (in pipeline related events this would be the operator).


Incorporated by reference (IBR)

Specific versions (by revision date) of various organization or industry standards, specifications, or recommended best practices and approved, wholly or in part, for incorporation by reference into regulations.

Source: §192.7, §195.3


Indirect inspection

Equipment and practices used to take measurements at ground surface above or near a pipeline to locate or characterize corrosion activity, coating holidays, or other anomalies.

Source: ANSI/NACE SP0502


Inert gas

A gas that is non-explosive and non-flammable. Operators use inert gases for testing and purging pipelines. The most common inert gas is nitrogen. High concentrations of inert gases may cause asphyxiation.


Inhibitors

An additive used to retard undesirable chemical action in a pipeline or pipeline facility when added in small quantities. Corrosion inhibitors can be broken down into a few main groups:

  1. Those that work by coating the surface with multiple layers, forming a barrier to the electrolyte.
  2. Those that chemically react with the surface, forming a protective film.
  3. Those that adsorb to the surface with no significant chemical reaction.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Injector type odorizer

A pump-type odorizer. The flow rate of the gas stream is monitored by an electronic sensor which, in turn, controls the odorant pump injection rate.


In-patient hospitalization

Requires both hospital admission and at least one overnight stay.

Source: Instructions for forms PHMSA F7000-1 (rev 11/2010) and PHMSA F 7100.2 (rev 11/2010)


In-plant piping system

Piping and devices that are located on the grounds of a plant and used to transfer hazardous liquid or carbon dioxide between plant facilities or between plant facilities and a pipeline or other modes of transportation, not including any device and associated piping that are necessary to control pressure in the pipeline.

Source: §195.2, §195.406(b)


Inspection

Use of a nondestructive testing technique

Source: ASME B31.8S 2004


Instant – off potential

The structure-to-soil potential immediately after all CP current is interrupted and prior to polarization decay.


Instant – on potential

The structure-to-soil potential immediately after CP current is applied and prior to polarization.


Instrument piping

Pipe, valves and fittings used to connect instruments to main piping, to other instruments and apparatus, or to measuring equipment.

Source: GPTC


Integrity assessment (IA)

Any of a variety of techniques (ILI, pressure test or direct assessment) used to determine the condition of the pipeline.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Integrity management (IM)

A risk-based approach to improving pipeline safety. Integrated and iterative processes for assessing and mitigating pipeline risks in order to reduce both the likelihood and consequences of incidents or accidents. These management and analysis processes integrate all available integrity-related data and information to assess the risks associated with pipelines, and then implement additional risk control measures.


Integrity management plan (IM Plan)

A written explanation of the mechanisms or procedures the operator will use to implement its integrity management program and to ensure compliance with this subpart.

Source: §192.1001


Integrity management program

A set of safety management, analytical, operations, and maintenance processes that are implemented in an integrated and rigorous manner to assure operators provide protection for HCAs. While the rules provide some flexibility for an operator to develop a program best suited for its pipeline system(s) and operations, there are certain required features – called “program elements” – which each integrity management program must have.

Source: https://primis.phmsa.dot.gov/comm/Im.htm


Integrity management program (IM Program)

An overall approach by an operator to ensure the integrity of its gas distribution system.

Source: 192.1001


Interference

Ionic current discharged through the electrolytic path from a metallic structure due to the suppression with the CP system of that structure.


Interference bond

An intentional metallic connection, between metallic systems in contact with a common electrolyte, designed to control electrical current interchange between the systems.

Source: NACE SP0169


Internal corrosion

Metal loss due to corrosion on the internal surfaces of a pipeline.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Internal corrosion direct assessment (ICDA)

Process an operator uses to identify areas along the pipeline where fluid or other electrolyte introduced during normal operation or by an upset condition may reside, and then focuses direct examination on the locations in covered segments where internal corrosion is most likely to exist. The process identifies the potential for internal corrosion caused by microorganisms, or fluid with CO2, O2, hydrogen sulfide or other contaminants present in the gas.

Source: §192.927(a)


Internal floating roof tank

A tank that has both a fixed roof and an internal floating roof. The fixed roof is usually a cone roof. The internal floating roof can be constructed of steel, aluminum, plastic or other material.

as used in Introduction to Aboveground Storage Tanks WBT


Interstate gas pipeline facility

A gas pipeline facility (a) used to transport gas; and (b) subject to the jurisdiction of the Commission under the Natural Gas Act (15 U.S.C. 717 et seq.)

Source: 49 U.S.C 60101
as used in Regulatory Overview WBT


Interstate pipeline

A pipeline or that part of a pipeline that is used in the transportation of hazardous liquids or carbon dioxide in interstate or foreign commerce.

Source: 195.2
as used in Regulatory Overview WBT


Intrastate gas pipeline facility

A gas pipeline facility and transportation of gas within a State not subject to the jurisdiction of the Commission under the Natural Gas Act (15 U.S.C 717 et seq.).
(A pipeline that begins and ends within a state.)

Source: 49 U.S.C 60101


Ion

An electrically charged atom or group of atoms.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


IR drop

The voltage drop across a resistance in accordance with Ohm’s Law.

Source: ANSI/NACE SP0502


Iron sulfide

FeS2 (Known as the mineral pyrite or marcasite). Generally formed as a corrosion product when H2S is present in steel pipelines.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Jeep

A method of holiday detection using an instrument that applies a voltage between the external surface of the coating and the pipe.

Source: GPTC


Joint

Refers to the connection between two lengths of pipe such as the weld joint for steel pipe and the heat fusion or glue joint for plastic pipe. Joint is also used as a slang term meaning a length of pipe i.e., joint of pipe.


Laminar flow

Laminar flow describes the relatively straight travel path of the fluid molecules within the pipe. The flow velocity decreases with the distance from the center of the pipe. The velocity profile of a fluid in laminar flow is bullet shaped and concentric about the centerline. This shape accounts for the larger interface or commingling of batched streams of crude oils. Laminar flow conditions within a pipeline will also yield increased water dropout in low-lying areas.


Laps

A surface imperfection in pipe that occurs during manufacturing. Laps often have the appearance of an irregular seam. The lap is a layer of pipe metal that has folded over onto itself during rolling but has not welded or fused to the underlying metal. Laps are usually completely attached to the pipe at one end, as opposed to scabs which may not be bonded about their periphery.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Large volume customer

A customer who receives similar volumes of gas as a distribution center. This may include factories, power plants and institutional users.

Source: §192.3


Launcher/receiver

Barrel-shaped appurtenance attached to a pipeline and able to be isolated from the pipeline pressure to facilitate launching pigs into the pipeline and receiving the pigs out of the pipeline.


Leak classification

A method of classifying leaks according to their size, hazard to persons or property and required remedial actions to reduce the hazard.


Leak test

A quality control check of the structural integrity of a pipeline performed by filling the line with a fluid, and applying a specified pressure for a prescribed period of time.
Any ruptures or leaks revealed by the test must be properly repaired.


Leakage survey

A systematic inspection of a pipeline for the purpose of finding leaks. on a gas piping system. Leakage surveys may be done with or without instruments, depending on the class location and type of system.

Source: GPTC


Length

A piece of pipe as delivered from the mill. Each piece is called a length regardless of its actual dimension however, 40 feet is typical for larger diameter pipe. While this is sometimes called “joint,” the term “length” is preferred.

Source: GPTC (PHMSA interpretation 192 Appendix BII, August 21, 2008)


Life-of-facility documents

The documents relating to design, materials, construction, testing, repairs and some corrosion records that must be maintained as long as the facility remains in service.


Light surface oxide

A non-damaging form of corrosion.

Source: GPTC


Line pipe

Steel or plastic pipe used in pipelines, gathering systems or flow lines.


Line section

A line section means a continuous run of transmission line between adjacent compressor stations, between a compressor station and storage facilities, between a compressor station and a block valve, or between adjacent block valves.

Source: §192.3


Line section

A continuous run of pipe between adjacent pressure pump stations, between a pressure pump station and terminal or breakout tanks, between a pressure pump station and a block valve, or between adjacent block valves.

Source: §195.2


Line section

A continuous run of pipe that is contained between adjacent pressure pump stations, between a pressure pump station and a terminal or breakout tank, between a pressure pump station and a block valve, or between adjacent block valves.

Source: §194.5


Linear polarization resistance (LPR)

A probe that instantantly measures corrosion rates by utilizing an electrochemical phenomenon known as linear polarization (polarization is the retardation in the corrosion rate in an electrochemical cell).

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Liquefied natural gas (LNG)

Natural gas or synthetic gas having methane (CH 4) as its major constituent which has been changed to a liquid.

Source: §193.2007


Liquefied petroleum gas (LPG)

A gas containing certain specific hydrocarbons which have been changed to a liquid under moderate pressure at normal temperatures. Propane and butane are principal examples.


Liquefied petroleum gas (LPG) air mixture

Liquefied petroleum gases distributed at relatively low pressures and normal atmospheric temperatures which have been diluted with air to produce desired heating value and utilization characteristics.


Liquid

A state of matter, neither solid or gas, characterized by free movement of molecules among themselves, but without the tendency to separate or disperse to fill every space of a container.


Listed specification

A specification listed in (49 CFR 192) Section I of Appendix B of 192.
(A technical specification created by a panel of experts of a recognized research and development entity (i.e. ASTM, ASME, API, etc.) on a particular component or best practice used on pipelines. These specifications are referenced within the pipeline regulations so that the details of the specification are considered to be enforceable without needing to be entirely re-stated.)

Source: §192.3
as used in Regulatory Overview WBT


Local distribution company (LDC)

A local gas company responsible for distributing gas to its customers. An LDC purchases gas from transmission companies for resale to the consumer. LDC’s operate and maintain the underground piping, regulators, and meters that connect to each residential and commercial customer.

as used in Regulatory Overview WBT


Lock-up

The point at which a regulator shuts off completely. Lock up is important so that, under no-flow conditions, the regulator does not seep gas downstream.


Long-term hydrostatic strength (of plastic pipe)

The estimated hoop stress of thermoplastic pipe, in psi, which would result in a failure of the pipe if it were subjected to 100,000 hours of hydrostatic pressure.

Source: GPTC


Low stress pipe

A hazardous liquid pipeline that is operated in its entirety at a stress level of 20% or less of the specified minimum yield strength of the line pipe.
(Low stress pipelines have limited jurisdiction by the Office of Pipeline Safety. Additional information regarding jurisdiction can be found in §195.12.)

Source: §195.2


Lower explosive limit (LEL)

The lower limit of flammability for a gas expressed as a percent, by volume, of gas in air.

Source: GPTC


Low-pressure distribution system

A distribution system in which the gas pressure in the main is substantially the same as the pressure provided to the customer.

Source: §192.3


Main

A distribution line that serves as a common source of supply for more than one service line.

Source: §192.3


Mainline valves

Valves positioned at locations along the pipeline system that can be closed down to isolate a line section.


Major river

A river that, because of its velocity and vessel traffic, would require a more rapid response in case of a worst case discharge. For a list of rivers see “Rolling Rivers, An Encyclopedia of America’s Rivers,” Richard A. Barlett, Editor, McGrawHill Book Company, 1984.

Source: §194.5


Malleable

Capable of being altered or controlled by outside forces. Normally referring to the condition of the steel used in constructing tanks.

as used in Introduction to Aboveground Storage Tanks WBT


Management of change (MOC)

A process that systematically recognizes and communicates to the necessary parties changes of a technical, physical, procedural, or organizational nature that can impact system integrity.

Source: ASME B31.8S 2004


Manhole

An access portal through the shell of the tank for workers to enter and exit.

as used in Introduction to Aboveground Storage Tanks WBT


Manometer

An instrument used to measure pressures. It consists of a tube in the shape of a U, partially filled with liquid of suitable density, usually water. When sources of different pressure are connected to each end of the manometer, the liquid is pushed up in the low-pressure side of the manometer and the difference in liquid level between the two sides of the U is an indication of pressure difference.


Manway

See manhole

as used in Introduction to Aboveground Storage Tanks WBT


Master meter

A pipeline system for distributing gas within, but not limited to, a definable area, such as a mobile home park, housing project, or apartment complex, where the operator purchases metered gas from an outside source for resale through a gas distribution pipeline system. The gas distribution pipeline system supplies the ultimate consumer who either purchases the gas directly through a meter or by other means, such as by rents.

Source: §191.3
as used in Regulatory Overview WBT


Maximum actual operating pressure

The maximum pressure that occurs during normal operations over a period of 1 year.

Source: §192.3


Maximum allowable hoop stress – gas

The maximum hoop stress permitted for the design of a piping system. It depends upon the material used, the class location of the pipe and the operating conditions.


Maximum allowable hoop stress – liquid

The maximum hoop stress permitted for the design of a piping system.


Maximum allowable operating pressure (MAOP)

Means the maximum pressure at which a pipeline or segment of a pipeline may be operated under Part 192.
(See §192.619 for further guidance.)

Source §192.3


Maximum allowable test pressure

The maximum internal fluid pressure permitted for testing pipe. The calculations will be dependant upon pipe materials, testing medium, intended operating pressures, class location, and proximity to buildings.


Maximum extent practicable

The limits of available technology and the practical and technical limits on a pipeline operator in planning the response resources required to provide the onwater recovery capability and the shoreline protection and cleanup capability to conduct response activities for a worst case discharge from a pipeline in adverse weather.

Source: §194.5


Maximum operating pressure (MOP)

The maximum pressure at which a pipeline or segment of a pipeline may be normally operated under Part 195.
(See §195.406 for further guidance)

Source: §195.2


MCF

A measurement term used to indicate one thousand cubic feet of gas.


Mechanical coupling

A fitting used for joining and pressure sealing two pipes together. Most couplings rely on elastomers and compression as sealing mechanisms.

Source: PHMSA ADB-08-02


Mechanical damage

Any number of types of anomalies in pipe, including dents, gouges, and metal loss, caused by the application of an external force.

Source: ANSI/NACE SP0502


Mechanical fitting

A mechanical device used to connect section of pipe. The term “Mechanical fitting” applies only to:

  1. Stab Type fittings;
  2. Nut Follower Type fittings;
  3. Bolted Type fittings; or
  4. Other Compressor Type fittings.

Source:


Mercaptan

A group of organic chemical compounds having a very strong and distinctive odor used for odorization of gas streams. Since natural gas is odorless, mercaptan is added to the gas so that people can smell escaping or leaking gas.


Metallurgical analysis

The evaluation of a material’s chemical, mechanical and structural properties through a number of different laboratory test methods.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Meter

Any mechanical device used to measure the volume throughput of natural gas or petroleum liquids.


Meter set assembly

The exposed portion of the service line extending from the service line riser valve to the connection of the customer’s fuel line, including the meter, and (if present) the regulator and relief vent line. In the absence of a service line riser valve, the meter assembly starts at the first exposed fitting. The meter set assembly does not include the customer’s buried or exposed fuel line. If the operator’s service line continues past the meter and connects to the customer’s fuel line at a location some distance downstream of the meter, the meter set assembly ends at the meter outlet valve (if present) or at the first exposed fitting (i.e., coupling or union) downstream of the meter.

Source: GPTC


Methane

CH 4 is the lightest in the paraffin series of hydrocarbons. It is colorless, odorless and flammable and forms the major portion of natural gas. It is also lighter than air and will rise if released from containment.


Microbiological testing

Methods used to determine the numbers and types of microorganisms present in a sample. A serial dilution is the common form of testing.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Microbiologically influenced corrosion (MIC)

Localized corrosion resulting from the presence and activities of microorganisms, including bacteria and fungi.

Source: ANSI/NACE SP0502


Mill scale

The oxide layer formed during hot fabrication or heat treatment of metals.

Source: NACE/ASTM G193 Corrosion Terms


Miter joint

A joint made by cutting the pipe at an angle and then joining the pieces together to form a bend.


MMCF

A measurement term used to indicate one million cubic feet of gas.


Monitoring regulators

A pressure regulator set in series with another pressure regulator for the purpose of providing automatic overpressure protection in the event of a malfunction of the primary regulator. Back-up regulator systems can be assembled in a variety of arrangements. Monitoring regulators are typically set at a control pressure slightly higher than the primary regulators.


Multi-jurisdictional tank

A tankage facility having both terminal and breakout tanks. This type of facility is subject to the dual jurisdiction of both EPA and DOT.


Municipality

A city, county, or any other political subdivision of a state.

Source: §192.3


Natural gas liquids

Heavy hydrocarbons found in natural gas, which may be extracted or isolated and processed as liquefied petroleum gas (LPG) (examples include propane, butane, and natural gasoline).


Natural Gas Pipeline Safety Act (NGPSA) of 1968

The Natural Gas Pipeline Safety Act of 1968 is the act passed by Congress which established regulatory authority over the transportation of gas by pipeline.


Navigable waters

The waters of the United States, including the territorial sea and such waters as lakes, rivers, streams; waters which are used for recreation; and waters from which fish or shellfish are taken and sold in interstate or foreign commerce.

Source: §194.5


Navigable waterways are those waterways ”where a substantial likelihood of commercial navigation exists. Further guidance in determining the navigable waterways is available in a geographic database of navigable waterways in and around the United States called the National Waterways Network. The database includes commercially navigable waterways and noncommercially navigable waterways. The database can be downloaded at:
http://www.ndc.iwr.usace.army.mil/db/waternet/data/WATERTL1.DBF
A map of the commercially navigable waterways portion of the National Waterways Network Database is in the National Pipeline Mapping System.

Source: Federal Register /Vol. 65, No. 175 / Friday, September 8, 2000, page 54441


Near-ground (NG) potential

A structure-to-electrolyte potential taken directly over the pipeline, at the spot of electrical connection.

Source: ANSI/NACE SP0502


Near-white blast cleaned surface

An abrasive blast cleaned steel surface that is free of all visible contaminants and foreign matter, but may have some random staining on no more than five (5) percent of the surface area.

Source: NACE/ASTM G193 Corrosion Terms


Needle valve

A small valve used to regulate small amounts of gas or fluid flow. It contains a pointed plug or needle resting in an orifice or tapered orifice in the valve body. By adjusting the needle’s position within the seat or orifice, small amounts of gas or liquids are finely regulated. Needle valves are typically used on instrument, control or sampling pipe.


Night cap

A plug or cap attached to the open end of a pipe or pipeline to keep foreign objects or matter out of the pipe. These “night caps” are often used on construction or repair jobs and are usually installed at the end of a workday or shift.


Noble metal

A metal with a standard electrode potential more positive than that of hydrogen.

Source: NACE/ASTM G193 Corrosion Terms


Nominal wall thickness

The wall thickness listed in the pipe specifications.

Source: §195.2


Nominal wall thickness

The wall thickness, in inches, computed by, or used in, the design formula for steel pipe in §192.105. Pipe may be ordered to this computed wall thickness without adding an allowance to compensate for the under-thickness tolerances permitted in approved specifications.

Source: GPTC


Non-critical interference bond

A metallic connection between adjacent buried structures which allow current flow that is not detrimental to the operator of the pipeline.


Non-destructive testing (NDT)

Testing in which the part being tested is not rendered unusable. NDT techniques include radiography (X-ray), ultrasonic, magnetic particles, dye penetrant, or ammonium persulfate.


NPMS

National Pipeline Mapping System


Occluded region

In an immersed system, a region that has limited access to the bulk environment in contact with the majority of the pipe preventing free exchange of ions.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Odorant

A chemical substance added to natural gas so that the odor can be used as a warning sign of the presence of escaping gas.
(For additional odorant requirements, see 192.625 ( c)).


Odorization

The process of adding an odor to natural gas. Since natural gas is odorless, odorant is added to the gas so that people can smell escaping or leaking gas and report to the gas companies for further investigation


Odorizer

A piece of equipment that adds chemical odorant to flowing natural gas pipelines.

Source:


Offshore

Beyond the line of ordinary low water along that portion of the coast of the United States that is in direct contact with the open seas and beyond the line marking the seaward limit of inland waters.

Source: §191.3, §192.3, §195.2


Oil

Oil of any kind or in any form, including, but not limited to, petroleum, fuel oil, vegetable oil, animal oil, sludge, oil refuse, oil mixed with wastes other than dredged spoil.

Source: §194.5


Oil Pollution Act of 1990 (OPA 90)

Public Laws 101 to 380 passed in 1990, substantially expanding existing legislation relating to the discharge of oil into navigable waters and onshore locations. Out of these laws came the 49 CFR Part 194 regulations concerning oil spill response plans for onshore pipelines.


Oil spill removal organization

An entity that provides response resources.

Source: §194.5


Onscene coordinator (OSC)

The federal official designated by the Administrator of the EPA or by the Commandant of the USCG to coordinate and direct federal response under subpart D of the National Contingency Plan (40 CFR part 300).

Source: §194.5


Onshore oil pipeline facilities

New or existing pipe, rights-of-way and any equipment, facility, or building used in the transportation of oil located in, on, or under, any land within the United Stated other than submerged land.

Source: §194.5


Operating stress

The stress imposed on a pipe or structural member under normal operating conditions.

Source: GPTC


Operator

A person who engages in the transportation of gas.

Source: §192.3
as used in Regulatory Overview WBT


Operator

A person who owns or operates pipeline facilities..

Source: §195.2
as used in Regulatory Overview WBT


Operator

A person who owns or operates onshore oil pipeline facilities.

Source: §194.5
as used in Regulatory Overview WBT


OPS

The Office of Pipeline Safety, which is part of the Pipeline and Hazardous Materials Safety Admininstration, U.S. Department of Transportation.

Source: §190.3


Other populated area

A place, as defined and delineated by the Census Bureau, that contains a concentrated population, such as an incorporated or unincorporated city, town, village, or other designated residential or commercial area.

Source: §195.45


Outer Continental Shelf (OCS)

Means all submerged lands lying seaward and outside the area of lands beneath navigable waters as defined in Section 2 of the Submerged Lands Act (43 U.S.C. 1301) and of which the subsoil and seabed appertain to the United States and are subject to its jurisdiction and control.

Source: §192.3, §195.2


Overpressure protection (OPP)

The devices or equipment installed for the purpose of preventing pressure in a pipe system or other facility from exceeding a predetermined limit.

Source: GPTC


Oxidation

  1. Loss of electrons by a constituent of a chemical reaction.
  2. Corrosion of a metal that is exposed to an oxidizing gas at elevated temperatures

Source: NACE/ASTM G193 Corrosion Terms
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Padding

The placing of material free of any hard objects (rocks, etc.) below, around and above the pipe during backfill in order to protect the pipe surface from puncture or excessive abrasion.


Parallel encroachment

Parallel encroachment describes that portion of the route of a pipeline system or main that lies within, or runs in a generally parallel direction, with the rights-of-way of a road, street, highway, railroad, or other utilities.

Source: GPTC


Parts per million (ppm)

A unit typically used to express chemical concentration, one part of the chemical in each one million (1,000,000) parts of the base material.


Peak shaving

The process of supplying additional gas volumes to supplement the throughput supply of pipeline gas during periods of extremely high demand. The use of LNG, propane or drawing reserves out of underground storage and pipeline vessels are methods of peak shaving.


Performance language

A regulatory approach that prescribes an end result (i.e., a certain level of pipeline safety) but leaves the method or how to achieve it up to the operator’s discretion. This approach is often used to allow each operator to accommodate their individual differences in equipment, procedures, and operational circumstances.

Source: PHMSA interpretation PI-89-023


Person

Any individual, firm, joint venture, partnership, corporation, association, State, municipality, cooperative association, or joint stock association, and includes any trustee, receiver, assignee, or personal representative thereof.

Source: §190.3, §192.3, §195.2


Personal protective equipment (PPE)

Personal equipment that protects the individual who wears it by placing a barrier between that individual and a potential or known hazard. Examples of PPE include protective eyewear, face shields, masks, gloves, boots, hats, clothing, and respirators.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Petrochemical

Chemicals derived from processing or refining crude oil or natural gas.


Petroleum

Crude oil, condensate, natural gasoline, natural gas liquids, and liquefied petroleum gas.

Source: §195.2


Petroleum gas

Propane, propylene, butane, (normal butane or isobutanes), and butylene (including isomers), or mixtures composed predominantly of these gases, having a vapor pressure not exceeding 1434 kPa (208 psig) at 38°C (100°F).

Source: §192.3


Petroleum product

Flammable, toxic, or corrosive products obtained from distilling and processing of crude oil, unfinished oils, natural gas liquids, blend stocks and other miscellaneous hydrocarbon compounds.

Source: §195.2


pH

The negative logarithm of the hydrogen ion concentration in a solution.
(The measurement of the hydrogen ion concentrations in solution. pH is a 14-point scale that measures the acidic or alkalinity value of a substance: strong acids have low pH values and strong bases have high pH values, with a value of 7 being considered neutral, anything less than 7 is considered an acid and greater than 7 are alkaline or bases).

Source: NACE/ASTM G193 Corrosion Terms
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


PHMSA

The Pipeline and Hazardous Materials Safety Administration of the United States Department of Transportation.

Source: §190.3


Pig

Any mechanical device inserted and run inside a pipeline.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Pinpointing

The process of locating the exact source of a gas leak along a pipeline route with a minimum of excavation. This is accomplished using a gas measuring analyzer and a non-sparking metal plunger bar to punch holes in the ground along the pipeline’s right-of-way (see “centering”).


Pipe

Any pipe or tubing used in the transportation of gas, including pipe-type holders.

Source: §192.3


Pipe micrometer

A precision measurement tool used to physically measure the thickness of a pipe cross section. Pipe micrometers usually have rounded anvils on the measuring surfaces to account for the curvature of the pipe surface in the measurement.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Pipe or line pipe

A tube, usually cylindrical, through which a hazardous liquid or carbon dioxide flows from one point to another.

Source: §195.2


Pipeline

All parts of those physical facilities through which gas moves in transportation, including pipe, valves, and other appurtenance attached to pipe, compressor units, metering stations, regulator stations, delivery stations, holders, and fabricated assemblies.

Source: §192.3
as used in Regulatory Overview WBT


Pipeline

All parts of an onshore pipeline facility through which oil moves including, but not limited to, line pipe, valves, and other appurtenances connected to line pipe, pumping units, fabricated assemblies associated with pumping units, metering and delivery stations and fabricated assemblies therein, and breakout tanks.

as used in Regulatory Overview WBT


Pipeline environment

Includes soil resistivity (high or low), soil moisture (wet or dry), soil contaminants that may promote corrosive activity, and other know conditions that could affect the probability of active corrosion.

Source: §192.3, §195.553


Pipeline facility

New and existing pipeline, rights-of-way, and any equipment, facility, or building used in the transportation of gas or in the treatment of gas during the course of transportation.

Source: §192.3


Pipeline facility

New and existing pipeline, rights-of-way, and any equipment, facility, or building used in the transportation of hazardous liquids or carbon dioxide.

Source: §195.2
as used in Regulatory Overview WBT


Pipeline or pipeline system

All parts of a pipeline facility through which a hazardous liquid or carbon dioxide moves in transportation, including, but not limited to, line pipe, valves and other appurtenances connected to line pipe, pumping units, fabricated assemblies associated with pumping units, metering and delivery stations and fabricated assemblies therein, and breakout tanks.

Source: §195.2


Pipe-supporting element

Consists of fixtures and structural attachments.


Pipe-type holder

A container or group of interconnected pipe containers installed at one location and used for the sole purpose of storing gas.

Source: GPTC


Pit gage

A measurement tool used to determine the depth of pits in a pipe surface. There are several types of pit gages available, each having a different level of precision.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Pitot tube

A small device that can be inserted into a pipe to measure the flow of liquid or gas. This device is composed of two tubes arranged in such a manner that will allow the measurement of both the velocity and static pressures of the flowing liquid or gas. The difference in these pressures is a function of the flow within the pipe.

Source: APGA


Pitting

Localized corrosion of a metal surface that is confined to a small area and takes the form of cavities called pits.

Source: NACE/ASTM G193 Corrosion Terms
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Planktonic bacteria

Bacteria that are freely floating in brine. Planktonic bacteria can become sessile bacteria by adhering to a surface.

Source: NACE TM0194 Internal Corrosion


Plastic

A material that contains one or more organic polymeric substances of high molecular weight as an essential ingredient, is solid in its finished state, and can be shaped by flow at some stage of its manufacture or processing into finished articles. The two general types of plastic are thermoplastic and thermosetting.
A material which contains, as an essential ingredient, an organic substance of high molecular weight. It is solid in its finished state and, at some stage of its manufacture or processing, was shaped or molded.

Source: GPTC


Plastic pipe joints

Locations in plastic pipe where another length of pipe has been joined to increase its length, change direction (such as an elbow) or attach another component or branch to the system. Plastic pipe joints can be adhesive joints, heat-fusion joints or solvent cement joints.


Plug valve

A quarter turn metal valve in which a pierced plug rotates in a tapered or cylindrical body to control flow through the valve. Plug valves are normally used in quick open or closed applications but sometimes can be used for throttling purposes. Plug valves cannot be used in piggable pipelines.


Polarization

The change from the open circuit potential as a result of current across the electrode/electrolyte interface.

Source: NACE SP0169


Polarization decay

The change in electrode potential with time resulting from the interruption of applied current.

Source: NACE/ASTM G193 Corrosion Terms


Polarized potential

The potential across the structure/electrolyte interface that is the sum of the corrosion potential and the cathodic polarization.

Source: NACE SP0169


Pontoon

Provides floatation to the floating roof systems of above ground tanks. Pontoons, as related to API-650 Appendix H, internal floating roof type “E” are generally tubular and are constructed of metals such as aluminum or stainless steel.

as used in Introduction to Aboveground Storage Tanks WBT


Positive displacement meter

A mechanical, fluid-measuring device that measures flowing volumes very accurately by filling and emptying chambers of specific volume; also known as a volume meter or volumeter. The displacement of a fixed volume of fluid may be accomplished by the action of reciprocating or oscillating pistons, rotating vanes or buckets, rotating disks, tanks or other vessels that automatically fill and empty.


Positive displacement pump

A self-priming pump where the delivered capacity is virtually constant regardless of discharge pressure. There are two types of positive displacement pumps: reciprocating (i.e., piston or plunger) pumps and rotating (i.e., screw-type) pumps. Positive displacement pumps are known for their ability to generate very high pressures but are usually limited in their throughput capacities.


Pot life

The maximum elapsed time during which a coating can be effectively applied after all components of the coating have been thoroughly mixed.

Source: NACE/ASTM G193 Corrosion Terms


Potential

Electrical pressure or voltage measured in volts; also called electromotive force (EMF).

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Potential impact circle

A circle of radius equal to the potential impact radius (PIR)

Source: §192.903


Potential impact radius (PIR)

The radius of a circle within which the potential failure of a pipeline could have significant impact on people or property. PIR is determined by the formula r = 0.69* (square root of (p*d \2\)), where `r’ is the radius of a circular area in feet surrounding the point of failure, `p’ is the maximum allowable operating pressure (MAOP) in the pipeline segment in pounds per square inch and `d’ is the nominal diameter of the pipeline in inches.
Note: 0.69 is the factor for natural gas. This number will vary for other gases depending upon their heat of combustion. An operator transporting gas other than natural gas must use section 3.2 of ASME/ANSI B31.8S-2001 (Supplement to ASME B31.8; incorporated by reference, see §192.7) to calculate the impact radius formula.

Source: §192.903


Pounds per square inch (psi)

The unit of pressure or measure of force on a given area. Within the oil and gas industry, psi normally refers to the pressure of the gas or product contained within the pipeline or pressure vessel.


Pounds per square inch absolute (psia)

The pressure expressed in pounds exerted on one square inch of surface area. The absolute refers to the total pressure sensed including the surrounding atmospheric pressure.


Pounds per square inch gauge (psig)

The pressure expressed in pounds exerted on one square inch of surface area. The designation “gauge” indicates the readings are already adjusted or biased to ignore the surrounding atmospheric pressure which is 14.7 psi at sea level. If a PSIG type of gauge were not connected to any pressure source, it would read zero even though it is actually sensing 14.7 psi at sea level.


Power tool cleaning

Removal of loose rust, loose mill scale, and loose coating by power tool chipping, descaling, sanding, wire brushing, and grinding.

Source: NACE/ASTM G193 Corrosion Terms


Presiding official

The person who conducts any hearing relating to civil penalty assessments, compliance orders or hazardous facility orders.

Source: §190.3


Pressure

The force on a given area expressed in pounds per square inch (psi) or its metric equivalent of kilo Pascal’s (kPa).


Pressure limiting station

An apparatus which, under abnormal conditions, will act to reduce, restrict or shut off the supply of gas flowing into a transmission line, main, holder, pressure vessel or compressor station piping in order to prevent the gas pressure from exceeding a predetermined limit. While normal pressure conditions prevail, the pressure limiting station may exercise some degree of control of the flow of gas or may remain in the wide-open position. Included in the station are any enclosures and ventilating equipment, and any piping and auxiliary equipment, such as valves, control instruments, or control lines.

Source: GPTC


Pressure regulating station

An apparatus installed for the purpose of automatically reducing and regulating the gas pressure in the downstream transmission line, main, holder, pressure vessel or compressor station piping to which it is connected. Included in the station are any enclosures and ventilating equipment, and any piping and auxiliary equipment, such as valves, control instruments, or control lines.

Source: GPTC


Pressure relief station

An apparatus installed to vent gas from a transmission line, main, holder, pressure vessel, or compressor station piping in order to prevent the gas pressure from exceeding a predetermined limit. The gas may be vented into the atmosphere or into a lower pressure gas system capable of safely receiving the gas being discharged. Included in the station are any enclosures and ventilating equipment, and any piping and auxiliary equipment, such as valves, control instruments, or control lines.

Source: GPTC


Pressure reversal failure

The occurrence of a failure of a defect at a pressure level that is below the pressure level that the defect has previously survived due to defect growth produced by the previous higher pressurization and possible subsequent damage upon depressurization.

Source: John F. Kiefner and Willard A. Maxey, “The Benefits and Limitation of Hydrostatic Testing”


Pressure test

A quality control check of the structural integrity of a pipeline performed by filling the line with a liquid or gas, and applying a specified pressure for a prescribed period of time.
May be called strength test. If water is used as the testing medium, it may be called a hydrotest.


Prime mover

An engine or turbine powered by natural gas.


Primer

A coating material intended to be applied as the first coat on an uncoated surface. The coating is specifically formulated to adhere to and protect the surface as well as to produce a suitable surface for subsequent coats.

Source: NACE/ASTM G193 Corrosion Terms


Private right-of-way

A land use grant obtained through negotiations between the private landowner and the pipeline company. The grant permits the pipeline operator to install and maintain the pipeline buried within or traversing over private property.


Processing

Any of a variety of methods designed to remove or separate elements of compounds (hydrocarbon and non-hydrocarbon) from raw natural gas. These methods include refrigeration, adsorption, or absorption processes. The resulting natural gas is considered pipeline quality.

as used in Introduction to Part 192 WBT


Product

The liquid petroleum hydrocarbon or other material stored in tanks.

as used in Introduction to Aboveground Storage Tanks WBT


Production

The phase of the petroleum industry that deals with bringing the oil and gas fluids to the surface, separating them as required, and either storing them or delivering them to a pipeline system for transportation.

as used in Introduction to Part 192 WBT


Production facility

Piping or equipment used in the production, extraction, recovery, lifting, stabilization, separation or treating of petroleum or carbon dioxide, or associated storage or measurement. (To be a production facility under this definition, piping or equipment must be used in the process of extracting petroleum or carbon dioxide from the ground or from facilities where CO2 is produced, and preparing it for transportation by pipeline. This includes piping between treatment plants which extract carbon dioxide, and facilities utilized for the injection of carbon dioxide for recovery operations.)

Source: §195.2


Propane

A colorless gas, C3H8, found in natural gas and petroleum and widely used as a fuel. It can be liquefied by temperature or pressure. When shipping liquid propane by pipeline, it is considered a hazardous liquid.

as used in Introduction to Part 192 WBT


Protective coating

A coating applied to a surface to protect the substrate from corrosion.

Source: NACE/ASTM G193 Corrosion Terms


Prototype

The original pattern on which all similar subsequent fittings of the kind and size are based.

Source: PHMSA interpretation PI-73-021


Public highway

A main direct road or thoroughfare in an area that is open to the public. Ownership and maintenance of a particular road should have no bearing on whether the road is a highway.

Source: PHMSA interpretation PI-78-031


Public place

A place that is generally open to all persons in a community as opposed to being restricted to specific persons. Churches, schools, and commercial buildings as well as any publicly owned right-of-way or property which is frequented by persons are considered to be public places under §192.11(a).

Source: PHMSA interpretation 192.11 11 December 6, 1974, PHMSA interpretation 192.11 – 13, November 18, 1975


Pump

A mechanical device used to move liquid substances from one location to another. Pumps may be used singly or in groups.


Purging

The act of replacing a gas, air or liquid with another fluid in a container or pipeline to prevent the formation of an explosive mixture.


Qualified

An individual has been evaluated and can (a) perform assigned covered tasks and (b) recognize and react to abnormal operating conditions

Source: §192.803, §195.503


Qualified individual

An English-speaking representative of an operator, located in the United States, available on a 24-hour basis, with full authority to activate and contract with required oil spill removal organization(s); activate personnel and equipment maintained by the operator; act as liaison with the OSC; and obligate any funds required to carry out all required or directed oil response activities.

Source: §194.5


Qualified welder

A welder who has demonstrated the ability to produce sound welds meeting the requirements of Title 49 CFR and is qualified under an operator’s welding program. Title 49 CFR §§192.227, 192.229, and 195.222 specify under which conditions and how often a welder must be re-qualified.


Qualified welding procedure

A detailed and destructively tested method by which sound welds can be produced. These procedures must be qualified under section 5 of API 1104 or section IX of the ASME Boiler and Pressure Vessel Code.


Radiography

A variety of processes of non-destructive testing that use electromagnetic radiation to produce a record, usually a film, to view a material and find defects. Examples of electromagnetic radiation are X-ray and gamma rays.


Reciprocating pump

A mechanical device which movse fluids by means of a piston or plunger operating from a crankshaft.


Rectifier

A device used to convert alternating current (AC) to direct current (DC).


Reduction

A reaction in which there is a decrease in valence resulting from a gain of electrons. Contrast with oxidation.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Reference electrode (half cell)

An electrode whose open-circuit potential is constant under similar conditions of measurement, which is used for measuring the relative potentials of other electrodes.

Source: NACE SP0169


Refinery

The physical plant and associated equipment used in the process of manufacturing marketable petroleum products from crude oil.


Regional director

The head of any one of the Regional Offices of the Office of Pipeline Safety, or a designee appointed by the Regional Director. Regional Offices are located in Trenton, NJ (Eastern Region); Atlanta, Georga (Southern Region); Kansas City, Missouri (Central Regions); Houston, Texas (Southwest Region); and Lakewood, Colorado (Western Region).

Source: §190.3


Regulator

A device used to control the pressure of the pipeline system to which it is connected.


Regulator station

Equipment installed for the purpose of automatically reducing and regulating the gas pressure in the downstream pipeline, main, holder, pressure vessel or compressor station piping to which it is connected. Included are piping and auxiliary devices such as valves, control instruments, control lines, the enclosure, and ventilation equipment. (see “pressure regulating station”).

Source: GPTC


Relief valve

A mechanical device designed to open automatically and release excess pressure above a preset pressure limit.


Remediation

A repair or mitigation activity an operator takes on a covered segment to limit or reduce the probability of an undesired event occurring or the expected consequences from the event.

Source: §192.903


Remote control valve (RCV)

A valve that is operated from a location remote from where the valve is installed. The RCV is usually operated by the supervisory control and data acquisition (SCADA) system. The linkage between the pipeline control center and the RCV may be by fiber optics, microwave, telephone lines, or satellite.

Source: §195.45


Remote Earth

A location on the earth far enough from the affected structure that the soil potential gradients associated with currents entering the earth from the affected structure are insignificant.

Source: NACE/ASTM G193 Corrosion Terms


Replaced service line

A gas service line where the fitting that connects the service line to the main is replaced or the piping connected to this fitting is replaced.

Source: §192.383


Resistance bond

A metallic path, where the amount of current is controlled by a permanent or adjustable resistance, installed to provide a return path for cathodic protection current to prevent corrosion due to interference or stray current.


Respondent

A person upon whom the OPS has served a notice of probable violation

Source: §190.3


Response activities

The containment and removal of oil from the water and shorelines, the temporary storage and disposal of recovered oil, or the taking of other actions as necessary to minimize or mitigate damage to the environment.

Source: §194.5


Response plan

The operator’s core plan and the response zone appendices for responding to the maximum extent practicable, to a worse case discharge of oil, or the substantial threat of such a discharge.

Source: §194.5


Response resources

The personnel, equipment, supplies, and other resources necessary to conduct response activities.

Source: §194.5


Response zone

A geographic area either along a length of pipeline or including multiple pipelines, containing one or more adjacent line sections, for which the operator must plan for the deployment of, and provide, spill response capabilities. The size of the zone is determined by the operator after considering available capability, resources, and geographic characteristics.

Source: §194.5


Reverse-current switch

A bond designed and constructed such that CP current can pass in only one direction.


Right-of-way (ROW)

A general term denoting land, property or interest therein, usually in a strip, acquired for or devoted to a specific purpose such as a highway or pipeline.

Source: GPTC


Riser

A general term for vertical runs of piping regardless of the size or application.


Risk analysis

A methodology for predicting the probability and consequence of a hazard to pipeline integrity.


Risk management

The systematic application, by the owner or operator of a pipeline facility, of management policies, procedures, finite resources, and practices to the tasks of identifying, analyzing, assessing, reducing, and controlling risk in order to protect employees, the general public, the environment, and pipeline facilities.

Source: 49 U.S.C. 60101


Risk management plan

A management plan utilized by a gas or hazardous liquid pipeline facility owner or operator that emcompasses risk management.

Source: U.S.C. 60101


Roof drain

A device that allows accumulated water to be drained from the topside of external floating roof systems.

as used in Introduction to Aboveground Storage Tanks WBT


Root pass

See “stringer pass”.


Rotary pump

A mechanical device consisting of a rotating shaft turning a screw, cam, gear, or plunger within a fixed casing.


Rupture

A rapid bursting open of a container such as a segment of pipeline.

Source:


Rupture

Complete failure of any portion of the pipeline.

Source: ASME B31.8S 2004


Rupture disc or rupture pin

A one-time use, non-reclosing, sacrificial pressure relief device that protects a vessel, equipment or system from over pressurization at a manufactured predetermined level.


Rural area

Outside the limits of any incorporated or unincorporated city, town, village, or any other designated residential or commercial area, such as a subdivision, a business or shopping center, or community development.

Source: §195.2


Sample piping

Pipe, valves and fittings used for the collection of samples of fluids.


Scab

A surface imperfection in pipe that occurs during manufacturing. The scab is a piece of pipe metal, debris or foreign material rolled into the pipe surface but not welded or fused to the underlying metal. Scabs are typically unbonded about their periphery, whereas laps are usually completely attached to the pipe at one end. Scabs sometimes fall out during pipeline operation and leave a pit.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Scaling

The formation of corrosion product layers and/or precipitates on a metal surface.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Scraper

Any device that is used to remove debris or deposits (such as scale, rust or paraffin) from tubing, casing, rods, flow lines, or pipelines.

Source: GPTC


Seal

A flexible device mounted to the perimeter of a floating deck to stop fugitive emissions from migrating through the gap that exists between the edge of a floating roof and the tank’s shell. It is required that this gap between the outer periphery of a floating roof and the tank shell be sealed by a flexible device that provides a reasonably close fit to the shell surfaces.

as used in Introduction to Aboveground Storage Tanks WBT


Seamless pipe

A wrought tubular product made without a welded seam. It is manufactured by hot working steel or, if necessary, by subsequently cold finishing the hot-worked tubular product to produce the desired shape, dimensions and properties.

Source: GPTC


Secondary containment

Backup containment for the capture of released product. Secondary containment shall be sized so as to contain the greatest amount of liquid that may be released from the largest tank within the diked area, assuming a full tank, and providing sufficient allowance for precipitation after taking into account protection provided by remote impoundments (see “NFPA 30”).

as used in Introduction to Aboveground Storage Tanks WBT


Secondary stress

Stress created in the pipe wall by loads other than internal gas or fluid pressure. Examples are backfill loads, traffic loads, beam action in an unsupported span, loads at supports, blasting, and at connections of improperly supported pipe.

Source: GPTC


Self tapping tee

A tapping tee with a self-contained cutter which is installed on in-service pipe for drilling a hole in the pipe.


Separation

A process whereby liquid hydrocarbons and other liquids or impurities are separated from natural gas.

as used in Introduction to Part 192 WBT


Serial dilution method

Method of enumerating bacteria in a sample via transfer to a series of growth media vials using successive 1:10 dilutions in each successive vial. Following an incubation period, the number of positive cultures provides an estimate of the number of bacteria in the original sample. For statistical validity this test is done with replicates and the population estimate is derived from a statistical table.

Source: NACE TM0194 Internal Corrosion


Service line

A distribution line that transports gas from a common source of supply to an individual customer, to two adjacent or adjoining residential or small commercial customers, or to multiple residential or small commercial customers served through a meter header or manifold. A service line ends at the outlet of the customer meter or at the connection to a customer’s piping, whichever is further downstream, or at the connection to customer piping if there is no meter.

Source: §192.3


Service line serving single-family

A gas service line that begins at the fitting that connects the service line to the main and serves only one single-family residence.

Source: §192.383


Service regulator

The device on a service line that controls the pressure of gas delivered from a higher pressure to the pressure provided to the customer. A service regulator may serve one customer or multiple customers through a meter header or manifold.

Source: §192.3


Service tee

A tee fitting installed to hot tap a main for the purpose of supplying gas to a new supply line or service line.


Sessile bacteria

Bacteria that are attached to surfaces. Bacteria that live in biofilms are sessile bacteria.

Source: NACE TM0194 Internal Corrosion


Shallow anode (conventional ground) bed

One or more anodes installed either vertically or horizontally at a nominal depth of less than 50 feet for the purpose of supplying CP current.

Source: NACE/ASTM G193 Corrosion Terms


Shelf life

The maximum length of time packaged materials can be stored, at specified conditions, and remain in usable condition.

Source: NACE/ASTM G193 Corrosion Terms


Shielding

High resistance or non-conducting material preventing CP current from reaching the structure, or low resistance material diverting the current away from the structure to be protected.


Shorted pipeline casing

A casing that is not electrically isolated from the carrier pipe. Generally, this term is used for casings that are in direct metallic contact with the carrier pipe.


Shot blasting

Abrasive blast cleaning using metallic (usually steel) shot as the abrasive.

Source: NACE/ASTM G193 Corrosion Terms


Shut-in test

A pressure test conducted on smaller size gas distribution or service piping done at delivery pressures to check for leaks; also called a leak test.


Side stream (test spool)

A bypass loop or a direct outlet from the process stream. Fluid may or may not be at the same velocity, temperature, and pressure as the main process stream. Often used for evaluating treatment chemicals, exposing corrosion monitoring devices, etc. A test spool is a short pipe section that can be removed for internal inspection. Test spools may be used in a side stream or other locations where flow can be temporarily stopped or diverted.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Small LPG operator

An operator of a liquefied petroleum gas (LPG) distribution pipeline that serves fewer than 100 customers from a single source.

Source: §192.1001


Smart pig

Any of a variety of inspection devices designed to be run while the pipeline remains in service. These devices, or “pigs”, measure and record the internal geometry, external or internal corrosion as well as provide information about pipe characteristics such as wall thickness and other pipe defects. Magnetic flux leakage, ultrasonic, calipers, and geometry are examples of smart tools; also referred to as ILI tools.


Solvent cement joint

A joint made in thermoplastic (usually polyvinylchloride or PVC) piping by the use of a solvent or solvent cement, which forms a continuous bond between the mating surfaces.

Source: GPTC


Solvent cleaning

Removal of oil, grease, dirt, soil, salts, and contaminants using organic solvents or other cleaners such as vapor, alkali, emulsion, or steam.

Source: NACE/ASTM G193 Corrosion Terms


Sound engineering practice

Reasoning exhibited or based on thorough knowledge and experience, logically valid and having technically correct premises that demonstrate good judgment or sense in the application of science.

Source: NACE RP0502


Sour

Fluids containing sulfur compounds or entrained hydrogen sulfide (H2S) at concentrations which may cause corrosion and require additional processing.


Sour gas

A gaseous environment containing hydrogen sulfide generally in concentrations of more the 4 ppm.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Special permit

An order by which PHMSA waives compliance with one or more of the Federal pipeline safety regulations under the standards set forth in 49 ISC 60118(c) and subject to conditions set forth in the order. A special permit is issued to a pipeline operator (or prospective operator) for specified facilities that are or, absent waiver, would be subject to the regulation.

Source: §190.341(a)


Specific gravity

The ratio of the weight of a given volume of a substance at a given temperature to the weight of a standard substance at the same temperature.

Source: NACE


Specified minimum yield strength (SMYS)

The minimum yield strength, expressed in pounds per square inch, prescribed by the specification under which the material is purchased from the manufacturer.

Source: §194.5


Specified minimum yield strength (SMYS)(gas)

  1. For steel pipe manufactured in accordance with a listed specification, the yield strength specified as a minimum in that specification; or
  2. For steel pipe manufactured in accordance with an unknown or unlisted specification, the yield strength determined in accordance with §192.107(b)

Source: §192.3


Specified minimum yield strength (SMYS)(liquid)

The minimum yield strength, expressed in p.s.i. (kPa) gage, prescribed by the specification under which the material is purchased from the manufacturer.

Source: §195.2


Spike hydrostatic test

A test in which the test pressure-to-operating pressure ratio significantly exceeds the minimum value of 1.25 required by federal regulations and the duration of which is considerably shorter than the minimum time of 8 hours also required by federal regulations. Test pressures that result in hoop stress levels between 100 percent and 110 percent of the specified minimum yield strength (SMYS) of the pipe, or in terms of Maximum Operating Pressure (MOP), 1.39 and 1.53, respectively, have typically been used for SHT.

Source: TTO Number 6, “Spike Hydrostatic Test Evaluation” Final Report, Michael Baker Jr., Inc, July, 2004
http://primis.phmsa.dot.gov/gasimp/docs/TTO06_SpikeHydrostaticTestEvaluation_FinalReport_July2004.pdf


Squeeze off tool

A maintenance device used with plastic pipe that clamps down on the pipe to restrict or totally block flow and hold system pressures of gas and enable system repair. The tool consists of flat or curved surfaces with minimum radii that come together against the pipe wall. Stops, used to prevent the pipe being squeezed beyond a minimum allowable distance specified by the pipe manufacturer, are normally an integral part of the tool.


Stable defect

A defect that never threatens the integrity of a pipeline within a predictable time period.

Source: Final Report No. 05-12R http://primis.phmsa.dot.gov/gasimp/docs/Evaluating_Stability_of_Defects.pdf


Standard cubic foot per hour (SCFH)

A volumetric flow rate measurement representing the amount of gas moved in one hour if it were at 60°F and under atmospheric pressure at sea level of 14.7 psi. Since gas moved within pipelines is rarely at these exact conditions, all raw flow rate data must be corrected to the standard so that variations in pressure and temperature can be accounted for.


State

Each of the several States, the District of Columbia, and the Commonwealth of Puerto Rico.

Source: §192.3


State

A State of the United States, the District of Columiba and the Commonwealth of Puerto Rico.

Source: §190.3


Static electricity

The build-up of an electric charge on the surface of objects that remains on an object until it is discharged.


Stationing (map stations, mileposts)

A measure of length used to identify locations along the pipeline which provides a geospatial reference for pipeline features and construction. Stationing is typically measured in feet, usually indicated as X+XX. Generally, the beginning of the pipeline route is designated as zero and station values increase along the route. Some operators use mile posts as a method of stationing.


Steel

An iron-base alloy, malleable in some temperature ranges as when initially cast, containing manganese, carbon and often other alloying elements.

Source: GPTC


Storage field

A geographic field containing a well or wells that are completed for and dedicated to subsurface storage of large quantities of gas for later recovery, transmission and end use.

Source: B31.8 2003


Stray current

Current which flows through paths other than the intended circuit.

Source: NACE SP0169


Strength test

A quality control check of the structural integrity of a pipeline performed by filling the line with a liquid or gas and applying a specified pressure for a prescribed period of time.
May be called a pressure test. If water is used as the testing medium, it may be called a hydrotest.


Stress

The resultant internal forces within a material that resists change in the size or shape of the material when acted on by external forces.

Source: GPTC


Stress concentrator

A discontinuity in a structure or a change in contour that causes a local increase in stress.

Source: ASME B31.8S 2004


Stress corrosion cracking (SCC)

The formation of cracks in metallic pipe, typically in a colony or cluster, as a result of the interaction of tensile stress, a corrosive environment, and a susceptible material.

Source: GPTC
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Stress level

The level of tangential or hoop stress, usually expressed as a percentage of specified minimum yield strength.

Source: §194.5, §195.2


Stringer pass

The initial welding pass to join two pieces of pipe together; also called root pass.


Stringing

The process of delivering and distributing line pipe or components where and when it is needed on the right-of-way during construction activities.


Structural attachments

Components which are welded, bolted or clamped to the pipe, such as clips, lugs, clamps, clevises, straps and skirts.


Structure-to-electrolyte potential

The potential difference between the surface of a buried or submerged metallic structure and the electrolyte that is measured with reference to an electrode in contact with the electrolyte.

Source: NACE SP0169


Subject matter experts (SMEs)

Persons knowledgeable about design, construction, operations, maintenance, or characteristics of a pipeline system. Designation as an SME does not necessarily require specialized education or advanced qualifications. Some SMEs may possess such expertise, but detailed knowledge of the pipeline system gained by working with it over time can also make someone an SME. SMEs may be employees, consultants, contractors, or any suitable combination of these.

Source: GPTC


Sulfate-reducing bacteria

A diverse variety of heterotrophic microorganisms characterized by it’s metabolism of sulfate to sulfide.

Source: NACE TM0194 Internal Corrosion
as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Sulfide

Any products produced by combining with a sulfur ion (S-2). These products may include hydrogen sulfide and iron sulfide.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Sulfide stress cracking

Cracking of a metal under the combined action of tensile stress and corrosion in the presence of water and hydrogen sulfide.

Source: NACE/ASTM G193 Corrosion Terms


Supervisory control and data acquisition (SCADA)

A computer-based system or systems used by a controller in a control room that collects and displays information about a pipeline facility and may have the ability to send commands back to the pipeline facility.

Source: §192.3, §195.2


Surface analysis techniques

Microscopic surface analysis techniques are methods for chemical analysis of thin films, distinct small regions or particles. Examples include energy dispersive x-ray spectroscopy (EDS), auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS) and Fourier Transform Infrared Spectroscopy (FTIR).

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Surface profile

The irregular peak and valley profile on a bare surface that can result from operations such as abrasive blast cleaning or power tool cleaning.

Source: NACE/ASTM G193 Corrosion Terms


Surge pressure

Pressure produced by a change in velocity of the moving stream that results from shutting down a pump station or pumping unit, closure of a valve, or any other blockage of the moving stream.

Source: §195.2


Sweet crude

Crude oil that contains little or no sulfur compounds or entrained H2S.


Tank farm

A group of tanks used to store crude oil and refined products.


Tapping tee or tapping saddle

A tee fitting used to connect an in-service pipeline used to make a new connection.


Task

An activity, identified by the operator, that

  1. is performed on a pipeline facility;
  2. is an operations or maintenance task;
  3. is performed as a requirement of this part; and
  4. affects the operations or integrity of the pipeline.

Source: §192.801, §195.501


Technical Pipeline Safety Standards Committee (TPSSC)

A group of individuals who review and report on the technical feasibility and supporting analyses, reasonableness, cost-effectiveness, practicability of the proposed standard and recommend actions. The committee is comprised of 15 members, five representing Government, four representing the pipeline industry and six designees from the general public with knowledge in the safety regulations of transporting gas.

as used in Regulatory Overview WBT


Telluric current

Current in the earth as a result of geomagnetic fluctuations.

Source: NACE SP0169


Tensile strength

The highest unit tensile stress (referred to the original cross section) that a material can sustain before failure (psi.)

Source: GPTC


Test spool

See “side stream”.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Test station (test point)

An aboveground electrical connection to an underground pipe or structure where pipe-to-soil potentials are taken to monitor CP.


Therm

A unit of measurement describing the amount of heat a material can generate. In the gas industry, a therm represents 100,000 BTU’s and is a common unit used in the sale of natural gas.


Thermoplastic pipe

A plastic pipe that is capable of being repeatedly softened by increase of temperature and hardened by decrease of temperature. These would include Polybutylene (PB), Polyethylene (PE), and Polyvinylchloride (PVC).

Source: GPTC


Thermosetting plastic pipe

A plastic pipe which is capable of being changed into a substantially infusible or insoluble product when cured under application of heat or chemical means. Reinforced fiberglass is a good example.

Source: GPTC


Third-party damage

Damage to pipelines and other facilities that can occur during excavation, digging, or other activities by persons not affiliated with the pipeline operator or their contractors.


Topcoat

The final coat of a coating system.
(also referred to as the finish coat)

Source: NACE/ASTM G193 Corrosion Terms


Toxic

Capable of causing injury or death, especially by chemical means. Poisonous.

as used in Introduction to Part 192 WBT


Toxic product

“Poisonous material” as defined by §173.132 Class 6, Division 6.1 – Definitions of this chapter.

Source: §195.2


Tracer wire

Metallic wire that is buried above plastic pipe that can be used to indicate the location of the adjacent buried plastic pipe.


Transmission line

A pipeline, other than a gathering line, that:

  1. transports gas from a gathering line or storage facility to a gas distribution center, storage facility, or large volume customer that is not down-stream from a gas distribution center;
  2. operates at a hoop stress of 20 percent or more of SMYS; or
  3. transports gas within a storage field.
    Note: A large volume customer may receive similar volumes of gas as a distribution center, and includes factories, power plants, and institutional users of gas.

Source: §192.3


Transporting gas

The gathering, transmission, or distribution of gas by pipeline or the storage of gas, in or affecting interstate or foreign commerce; and the movement of gas through regulated gathering lines.

Source: U.S.C. 60101


Transportation of gas

The gathering, transmission, or distribution of gas by pipeline or the storage of gas, in or affecting interstate or foreign commerce.

Source: §192.3


Transporting hazardous liquid

The movement of hazardous liquid by pipeline, or the storage of hazardous liquid incidental to the movement of hazardous liquid by pipeline, in or affecting interstate or foreign commerce; and the movement of hazardous liquid through regulated gathering lines.

Source: U.S.C. 60101


Trench

A long ditch cut into the ground dug by a backhoe or by a specialized digging machine such as a trencher, for the purpose of installing a pipeline.


Trunk line

A piping system used to transport natural gas or liquids from the producing areas of the country to the refineries, terminal, or interconnections.

Source: APGA


Tubing

Smaller diameter pipe (usually stainless steel or copper) with diameter usually less than 1/2 inch that is generally used as instrumentation or control piping, to sense pipeline conditions for instrumentation monitoring and control.


Turbulent flow

The chaotic and random flow patterns that occur as fluid moves through a pipeline. Although it requires more energy, hazardous liquid pipelines prefer to operate in the turbulent flow mode because less commingling or interface occurs between batches. The haphazard molecular flow pattern also keeps sediment and water mixed up or suspended in the flow stream.


Ultimate strength

The maximum stress that a material can sustain.


Ultrasonic testing

A non-destructive inspection method consisting of an instrument with a probe that generates high-frequency sound waves and measures the waves reflection off the pipe inner wall. Ultrasonic probes must be “coupled” to the pipe with some sort of liquid and is used to determine the condition of the pipeline facilities.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Ultrasonic wall thickness meter

This device is particularly useful in locating internal corrosion in steel pipe where some of the inner wall surface may be corroded away. UT wall thickness meters are the simplest application of this technology, and are used frequently by field personnel. UT meters must be checked and calibrated before use.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Umbrella-roof tank

A modification of the cone-roof tank. The umbrella-roof uses segmental plates arched on meridian centerlines. The roof receives its name from the visible “ribs” which occur at the roof plate joints; often resembling that of an umbrella

as used in Introduction to Aboveground Storage Tanks WBT


Unaccounted for gas

The difference between the total gas purchased from all sources and the total gas accounted for as sales, net interchange, and internal company use. This difference includes leakage or other actual losses, discrepancies due to meter inaccuracies, variations of temperature and/or pressure, and other variants, particularly billing lag.


Underground storage

The utilization of subsurface facilities for storing hydrocarbon fluids which can later be withdrawn as required for a variety of operational reasons. Storage facilities can include natural geologic features such as depleted hydrocarbon reservoirs, salt domes or aquifers or manmade caverns.


Union

A specialized threaded fitting used to couple two joints of threaded pipe together, without having to turn or dismantle either run of pipe.


Unusually sensitive area

A drinking water or ecological resource area that is unusually sensitive to environmental damage from a hazardous liquid pipeline release, as identified under §195.6.

Source: §195.2


Upper explosive level (UEL)

The maximum amount of airborne fuel that can be present in an air-fuel mixture and still be explosive. An air- fuel mixture above the UEL is considered too rich to ignite.


Upstream

The direction the fluid is coming from in regard to a reference point. With compressor and pump stations, upstream would be the suction side of the facility.


Valve

A mechanical device used to control the flow of gas or liquid. A valve can be used solely for fully open or closed applications, to control the direction of flow, or used to throttle flow or regulate pressure. Valve types include plug valves, ball valves, globe valves and gate valves.

as used in Regulatory Overview WBT
as used in Introduction to Part 192 WBT


Valve box

A protective container installed around an underground valve to allow operation or maintenance access to underground pipeline valves.


Vapor pressure

The pressure on the surface of a confined liquid caused by the vapors of that liquid. The “vapor pressure” is reached for a particular liquid at a particular temperature when the balance between evaporation and condensation has reached equilibrium. Vapor pressure varies with temperature and increases as the temperature rises.

as used in Introduction to Aboveground Storage Tanks WBT


Vault

An underground structure which may be entered, and which is designed to contain piping and piping components such as valves or pressure regulators.

Source: GPTC


Vent

An opening or a device affixed to a storage tank that is designed to relieve pressure and/or vacuum. Suitable vents are required to be provided to prevent overstressing of the roof deck or seal membrane.

as used in Introduction to Aboveground Storage Tanks WBT


Viscosity

The resistance to flow in a particular fluid.


Voltage

An electromotive force or a difference in electrode potentials expressed in volts

Source: NACE SP0169


Warning tape

A tape installed above a pipeline or tracer wire to warn excavators of the proximity of the pipeline.


Water cut

The amount of water present in a gas or liquid hydrocarbon pipeline system.

as used in Investigating and Managing Internal Corrosion of Pipelines WBT


Welding

A method of joining metal together using heat to fuse the pieces. Examples of welding processes are: submerged metal arc welding, oxyacetylene welding, and electrical resistance welding.

Source:


Well

A hole made by a drill bit during the oil and gas production process. The completed oil or gas production location is also referred to as a well.

as used in Introduction to Part 192 WBT


Wet film thickness

The thickness of a coating measured immediately after application before any appreciable solvent has evaporated or drying has taken place.

Source: NACE/ASTM G193 Corrosion Terms


Wet gas

Natural gas containing liquid, including water or liquefiable hydrocarbons such as natural gasoline, butane, pentane and other light hydrocarbons that can be removed by chilling, pressurization, or other extraction methods. For operator established tariff purposes, any gas containing water vapor in excess of 7 pounds per million cubic feet (mmcf) is considered wet gas.


White metal blast cleaned surface

An abrasive blast cleaned steel surface that is free of all visible contaminants, foreign matter, and staining.

Source: NACE/ASTM G193 Corrosion Terms


Wick-type odorizer

Equipment that odorizes the natural gas by having the natural gas flow across a wick in a pipe bottle saturated with odorant. Wick-type odorizers are generally used for odorizing individual lines such as farm taps.


Wireline or tethered pig

A mechanical device run inside an out-of-service pipeline between one or more openings cut in the pipeline. Wireline pigs are tethered to a wireline cable and are propelled by pulling on the cable.


Worst case discharge

The largest foreseeable discharge of oil, including a discharge from fire or explosion, in adverse weather conditions. This volume will be determined by each pipeline operator for each response zone and is calculated according to §194.105.

Source: §194.5


Wrinkle bend

Bends made by the obsolete practice of bending prior to the advent of smooth bending technology. These consist of circumferentially oriented ripples at the intrados (interior surface of an arch) of the bend.

Source: Final Report No. 05-12R
http://primis.phmsa.dot.gov/gasimp/docs/Evaluating_Stability_of_Defects.pdf


X-ray

A specific radiographic method of non-destructive testing that uses X-rays to produce a film that is used to analyze the quality of welded joints in metallic pipe. See radiography.


Yield strength

The yield strength is the stress level at which a material exceeds its elastic limits and the material begins to permanently deform.


You

The operator.

Source: §195.553