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permanently removed from service that has been physically separated from its source of gas or hazardous liquid and is no longer maintained under regulation 49 CFR Parts 192 or 195, as applicable.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

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

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

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 (ground) bed

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

Source: NACE SP0169

Anomaly

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

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

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.

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).

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

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.

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

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

Blushing

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

Source: NACE/ASTM G193 Corrosion Terms

Bond

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

Source: NACE SP0169

Bracelet anode

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

Source: NACE/ASTM G193 Corrosion Terms

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.

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

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 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

Casing

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

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

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

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 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.

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

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

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

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®.

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.

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 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 rate

The rate at which corrosion proceeds.

Source: NACE SP0169

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 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.

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:

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.

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)

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

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

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.

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

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.

Dry film thickness

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

Source: NACE/ASTM G193 Corrosion Terms

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 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

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

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 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.

Environment

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

Source: NACE/ASTM G193 Corrosion Terms

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

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

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

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

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

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

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.

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.

Flaring

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

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.

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.

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

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.

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.

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.

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

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.

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.

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

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

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.

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).

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

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 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

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)

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 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 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)

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.

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 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.

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

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.

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.

Lower explosive limit (LEL)

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

Source: GPTC

Mainline valves

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

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.

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

Meter

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

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.

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 waterway

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

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

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

Operating stress

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

Source: GPTC

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.

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

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

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

Pipe-supporting element

Consists of fixtures and structural attachments.

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

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

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

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 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.

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.

Product

The liquid petroleum hydrocarbon or other material stored in tanks.

as used in Introduction to Aboveground Storage Tanks 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

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 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).

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.

Relief valve

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

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

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.

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 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

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.

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

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

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

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

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

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.

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

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

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

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

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.

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

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

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.

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.

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

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.

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:

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

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

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.