Pipeline regulatory glossary

means permanently removed from service.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means continuing corrosion that, unless controlled, could result in a condition that is detrimental to public safety.

means the Administrator, Pipeline and Hazardous Materials Safety Administration or his or her delegate.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

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

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means a series of closely and properly spaced pipe-to-electrolyte potential measurements taken over the pipe to assess the adequacy of cathodic protection or to identify locations where a current may be leaving the pipeline that may cause corrosion and for the purpose of quantifying voltage (IR) drops other than those across the structure electrolyte boundary, such as when performed as a current interrupted, depolarized, or native survey.

means materials used to make pipe or components manufactured with a combination of either steel and/or plastic and with a reinforcing material to maintain its circumferential or longitudinal strength.

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

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means 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 operational functions of the pipeline facility.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means the meter that measures the transfer of gas from an operator to a consumer.

means the initial point where gas enters piping used primarily to deliver gas to customers who purchase it for consumption, as opposed to customers who purchase it for resale, for example: (1) At a metering location; (2) A pressure reduction location; or (3) Where there is a reduction in the volume of gas, such as a lateral off a transmission line.

means a pipeline other than a gathering or transmission line.

means gas above its dew point and without condensed liquids.

means 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 pipeline.

means an eligible Class 3 segment and the upstream and downstream portion of the transmission line that is capable of being assessed with an in-line inspection tool extending from the nearest in-line inspection tool launcher to the nearest in-line inspection tool receiver.

means a segment of a transmission line in a Class 3 location that is capable of being assessed with an instrumented in-line inspection tool which does not contain: bare pipe; wrinkle bends; pipe with a seam formed by lap welding; a seam with a longitudinal joint factor below 1.0; or a segment which has experienced an in-service leak or rupture due to cracking in the pipe body, seam, or girth weld on the segment or segments of similar characteristics in or within 5 miles.

means a documented analytical procedure based on fracture mechanics principles, relevant material properties (mechanical and fracture resistance properties), operating history, operational environment, in-service degradation, possible failure mechanisms, initial and final defect sizes, and usage of future operating and maintenance procedures to determine the maximum tolerable sizes for imperfections based upon the pipeline segment maximum allowable operating pressure.

means, for the purposes of §§ 192.179 and 192.634, where 2 or more miles, in the aggregate, of onshore transmission pipeline have been replaced within any 5 contiguous miles of pipeline within any 24-month period. This definition does not apply to any gathering line.

means 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.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means natural gas, flammable gas, or gas which is toxic or corrosive.

means a pipeline that transports gas from a current production facility to a transmission line or main.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means the waters from the mean high water mark of the coast of the Gulf of America 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.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means an area on steel pipe material with a minimum dimension greater than two inches (50.8 mm) in any direction and hardness greater than or equal to Rockwell 35 HRC (Brinell 327 HB or Vickers 345 HV10).

means, for the purposes of this part, 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 waters less than 15 feet (4.6 meters) deep, as measured from the mean low water.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

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

means an inspection of a pipeline from the interior of the pipe using an inspection tool also called intelligent or smart pigging. This definition includes tethered and self-propelled inspection tools.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

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.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means a specification listed in section I of appendix B of this part.

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

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

means 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.

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

means the maximum pressure at which a pipeline or segment of a pipeline may be operated under this part.

means a city, county, or any other political subdivision of a State.

means the notification to, or observation by, an operator of indicia identified in § 192.635 of a potential unintentional or uncontrolled release of a large volume of gas from a pipeline. This definition does not apply to any gathering line.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means 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.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means a person who engages in the transportation of gas.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

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.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

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

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

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

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

means 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.

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

means new and existing pipelines, 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.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

(RMV) means an automatic shut-off valve (ASV) or a remote-control valve (RCV) that a pipeline operator uses to minimize the volume of gas released from the pipeline and to mitigate the consequences of a rupture. This definition does not apply to any gathering line.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means 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.

means 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.

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

means 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.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means a pipeline or connected series of pipelines, other than a gathering line, that: (1) Transports gas from a gathering pipeline or storage facility to a distribution center, storage facility, or large volume customer that is not down-stream from a distribution center; (2) Has an MAOP of 20 percent or more of SMYS; (3) Transports gas within a storage field; or (4) Is voluntarily designated by the operator as a transmission pipeline. Note 1 to transmission line. A large volume customer may receive similar volumes of gas as a distribution center, and includes factories, power plants, and institutional users of gas.

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

(UNGSF) means a gas pipeline facility that stores natural gas underground incidental to the transportation of natural gas, including: (1) (1) (i) A depleted hydrocarbon reservoir; (ii) An aquifer reservoir; or (iii) A solution-mined salt cavern. (2) In addition to the reservoir or cavern, a UNGSF includes injection, withdrawal, monitoring, and observation wells; wellbores and downhole components; wellheads and associated wellhead piping; wing-valve assemblies that isolate the wellhead from connected piping beyond the wing-valve assemblies; and any other equipment, facility, right-of-way, or building used in the underground storage of natural gas.

means a device or method used when pulling polyethylene pipe, typically through methods such as horizontal directional drilling, to ensure that damage will not occur to the pipeline by exceeding the maximum tensile stresses allowed.

means a person who performs manual or semi-automatic welding.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means a person who operates machine or automatic welding equipment.

Also defined separately in §195.2 (Part 195). The meaning can differ; check the Part you are reading.

means a bend in the pipe that: (1) Was formed in the field during construction such that the inside radius of the bend has one or more ripples with: (i) An amplitude greater than or equal to 1.5 times the wall thickness of the pipe, measured from peak to valley of the ripple; or (ii) With ripples less than 1.5 times the wall thickness of the pipe and with a wrinkle length (peak to peak) to wrinkle height (peak to valley) ratio under 12. (2) (2) (i) If the length of the wrinkle bend cannot be reliably determined, then wrinkle bend means a bend in the pipe where (h/D)*100 exceeds 2 when S is less than 37,000 psi (255 MPa), where (h/D)*100 exceeds (47000—S)/10,000 +1 for psi [(324—S)/69 +1 for MPa] when S is greater than 37,000 psi (255 MPa) but less than 47,000 psi (324 MPa), and where (h/D)*100 exceeds 1 when S is 47,000 psi (324 MPa) or more. (ii) Where: (A) D = Outside diameter of the pipe, in. (mm); (B) h = Crest-to-trough height of the ripple, in. (mm); and (C) S = Maximum operating hoop stress, psi (S/145, MPa).

means permanently removed from service.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means the Administrator, Pipeline and Hazardous Materials Safety Administration or his or her delegate.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

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

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means a unit of measurement equal to 42 U.S. standard gallons.

means a tank used to (a) relieve surges in a hazardous liquid pipeline system or (b) receive and store hazardous liquid transported by a pipeline for reinjection and continued transportation by pipeline.

means a fluid consisting of more than 90 percent carbon dioxide molecules compressed to a supercritical state.

means any part of a pipeline which may be subjected to pump pressure including, but not limited to, pipe, valves, elbows, tees, flanges, and closures.

means a software-based monitoring tool that alerts the pipeline dispatcher of a possible pipeline operating anomaly that may be indicative of a commodity release.

means when it can be reasonably determined, based on information available to the operator at the time a reportable event has occurred, even if only based on a preliminary evaluation.

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

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means 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 operational functions of the pipeline facility.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means “corrosive material” as defined by § 173.136 Class 8-Definitions of this chapter.

means 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.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means “flammable liquid” as defined by § 173.120 Class 3-Definitions of this chapter.

means a pipeline 219.1 mm (8⅝ in) or less nominal outside diameter that transports petroleum from a production facility.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means the waters from the mean high water mark of the coast of the Gulf of America 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.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means, for the purposes of this part, 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 waters less than 15 feet (4.6 meters) deep, as measured from the mean low water.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means petroleum, petroleum products, anhydrous ammonia, and ethanol or other non-petroleum fuel, including biofuel, which is flammable, toxic, or would be harmful to the environment if released in significant quantities.

means the inspection of a pipeline from the interior of the pipe using an in-line inspection tool. Also called intelligent or smart pigging.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means piping that is 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 mode of transportation, not including any device and associated piping that are necessary to control pressure in the pipeline under § 195.406(b).

means 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.

means a pipeline or that part of a pipeline to which this part applies that is not an interstate pipeline.

means 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.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means a hazardous liquid pipeline that is operated in its entirety at a stress level of 20 percent or less of the specified minimum yield strength of the line pipe.

means the maximum pressure at which a pipeline or segment of a pipeline may be normally operated under this part.

means the wall thickness listed in the pipe specifications.

means the notification to, or observation by, an operator of indicia identified in § 195.417 of a potential unintentional or uncontrolled release of a large volume of commodity from a pipeline. This definition does not apply to any gathering line.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means 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.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means a person who owns or operates pipeline facilities.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

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.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means 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.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means crude oil, condensate, natural gasoline, natural gas liquids, and liquefied petroleum gas.

means 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.

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

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means 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.)

(RMV) means an automatic shut-off valve (ASV) or a remote-control valve (RCV) that a pipeline operator uses to minimize the volume of hazardous liquid or carbon dioxide released from the pipeline and to mitigate the consequences of a rupture. This definition does not apply to any gathering line.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

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

means a stress corrosion cracking (SCC) cluster in which the deepest crack, in a series of interacting cracks, is greater than 10% of the wall thickness and the total interacting length of the cracks is equal to or greater than 75% of the critical length of a 50% through-wall flaw that would fail at a stress level of 110% of SMYS.

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

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

means 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.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means 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.

means “poisonous material” as defined by § 173.132 Class 6, Division 6.1-Definitions of this chapter.

means 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.

means a person who performs manual or semi-automatic welding.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

means a person who operates machine or automatic welding equipment.

Also defined separately in §192.3 (Part 192). The meaning can differ; check the Part you are reading.

An order issued by PHMSA that imposes requirements on a pipeline operator. Can be a corrective action order after an incident, a consent agreement following enforcement, or an amendment to a special permit. Context determines the specific meaning.

Consensus technical standards developed by the American Petroleum Institute, many incorporated by reference into 49 CFR Parts 192 and 195. Common examples include API 1163 (in-line inspection), API 1160 (integrity management for hazardous liquid pipelines), API 5L (line pipe specification).

An emergency order issued by PHMSA under 49 CFR 190.233 requiring an operator to take specified corrective actions when a pipeline facility is determined to be hazardous. Usually issued after incidents; typically includes pressure restrictions and mandatory inspections.

A written program required under 49 CFR 192 Subpart P for operators of gas distribution pipelines. DIMP programs identify threats, assess and rank risks, and implement measures to address those risks. Distinct from transmission integrity management (TIMP) under Subpart O.

A four-step process (pre-assessment, indirect inspection, direct examination, post-assessment) used to assess external corrosion threats on a pipeline segment. One of the integrity assessment methods permitted under the integrity management regulations.

A statutorily chartered advisory committee that reviews and makes recommendations on proposed PHMSA rulemakings affecting natural gas pipeline safety. Membership draws from industry, state regulators, and public safety representatives. Meetings are public and on the record.

The regulatory mechanism by which external consensus standards (API, ASME, ANSI, etc.) acquire the force of law in the CFR. Listed in 49 CFR 192.7 and 195.3, IBR'd standards must be complied with as if written into the regulation itself.

Assessment methodology for internal corrosion, analogous in structure to ECDA but targeting internal threats. Used for dry gas systems (DG-ICDA), liquid petroleum systems (LP-ICDA), and wet gas systems (WG-ICDA). Not permitted for all pipeline types.

Inspection of a pipeline's internal surface using an instrumented tool (a "pig") that traverses the line during operation. Common tool types include magnetic flux leakage (MFL) for metal loss and ultrasonic tools for crack detection. Results feed integrity management decisions.

An operator's documented program for assessing and managing the integrity of pipeline segments in high consequence areas. Required under 49 CFR 192 Subpart O (gas transmission) and 195.452 (hazardous liquid). Programs address threat identification, assessment methods, risk analysis, and preventive/mitigative measures.

Formerly used interchangeably with "IVP" for the integrity verification requirements under the Mega Rule. Now less common — current references typically use "IVP." Also used in some operator documents to mean "Internal Qualification Program" for operator qualification under Subpart N.

The set of requirements in 49 CFR 192 that mandate reconfirmation of maximum allowable operating pressure (MAOP) for gas transmission pipelines using one of six specified methods. Added by the Gas Mega Rule; phased compliance deadlines run through 2035.

Statutorily chartered advisory committee that reviews and makes recommendations on proposed PHMSA rulemakings affecting hazardous liquid pipeline safety. Parallel to GPAC for liquid pipelines. Meetings are public and on the record.

A geographic area introduced by the Mega Rule (Phase 1) where a pipeline failure would have moderate — but not high — consequences to public safety. Triggers a subset of integrity management requirements less stringent than HCA but above general compliance.

Industry shorthand for PHMSA's omnibus 2019 rulemaking (RIN 2137-AE72) revising 49 CFR Part 192, published in three phases. Added MAOP reconfirmation (IVP), expanded integrity management to non-HCA moderate consequence areas, and updated gathering line definitions. Often referenced as "Mega Rule Part 1/2/3" for the three phases.

A formal PHMSA enforcement document issued under 49 CFR 190.207 alleging that an operator violated one or more pipeline safety regulations. Includes proposed civil penalties and proposed corrective actions. Operators have 30 days to respond and may contest allegations.

The regulatory program in 49 CFR 192 Subpart N (gas) and 195 Subpart G (liquid) requiring operators to qualify individuals who perform covered tasks on pipelines. Covers training, testing, evaluation, and reevaluation intervals for those tasks.

The U.S. Department of Transportation agency responsible for regulating pipeline safety (Office of Pipeline Safety) and hazardous materials transportation. Publishes and enforces 49 CFR Parts 190–199 for pipelines.

PHMSA's public-facing pipeline safety data portal (primis.phmsa.dot.gov). Hosts incident reports, annual reports, enforcement actions, and the pipeline mileage database. Many compliance professionals use "PRIMIS" and "PHMSA's public data" interchangeably.

A valve placed on certain gas transmission pipeline segments required by the Mega Rule to automatically or remotely isolate the segment within 30 minutes of a rupture. Spacing and placement requirements depend on pipe diameter and location class.

The computerized control system used by pipeline operators to remotely monitor and control pipeline operations — valves, pressures, flow rates, leak detection inputs. Referenced throughout 49 CFR 195 for hazardous liquid pipelines (sections 195.446 and related).

Assessment methodology specifically for stress corrosion cracking threats. Requires more specialized application than ECDA/ICDA because SCC is environmentally dependent on coating condition, soil chemistry, and operating stress levels.

The minimum yield strength (in psi) specified in the line pipe specification for a particular steel grade. Used throughout 49 CFR 192 and 195 to calculate maximum allowable operating pressure (MAOP) via the Barlow formula and design factor.

The integrity management program required for gas transmission pipelines under 49 CFR 192 Subpart O. Covers threat identification, baseline assessment, periodic reassessment, and preventive/mitigative measures for segments in HCAs (and, post-Mega-Rule, MCAs).

A high-authority PHMSA interpretation letter that establishes enforcement policy on a specific regulatory question. Treated as authoritative source guidance in audit and compliance contexts. Tracked in Kondwit's PolicyDocument model with source-authority hierarchy.