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Glossary

This page contains a dynamic list of Pipeline-related terms and definitions.  These also appear in the main PHMSA glossary.  You can find another extensive list of Pipeline-related terms on the Stakeholder site.

Abandoned pipeline
A pipeline that is physically separated from its source of gas and is no longer maintained under 49 CFR Part 192.[more]
Abandonment
The process of abandoning a pipeline. [more]
ABS
An acronym for acrylonitrile butadiene styrene.[more]
Absolute humidity
The measure of the amount of water vapor actually in the air. Often stated as pounds of water vapor per pound of dry air. At any given temperature, relative humidity equals 100 times the absolute humidity divided by the greatest amount of water vapor that can be present in the air at that temperature.[more]
Absolute pressure
Gauge pressure plus barometric pressure. Absolute pressure can be zero only in a perfect vacuum. [more]
Absolute roughness
The average height of the microscopic irregularities in the surface of the pipe, at the pipe wall. [more]
Acceptable Level of Risk
for regulations and special permits is established by consideration of risk, cost/benefit and public comments. Relative or comparative risk analysis is most often used where quantitative risk analysis is not practical or justified. Public participation is important in a risk analysis process, not only for enhancing the public's understanding of the risks associated with hazardous materials transportation, but also for insuring that the point of view of all major segments of the...[more]
Acknowledgment, ACK
The process of informing a transmitting node that a message has been received correctly. Also, it is a means to indicate the readiness to receive in an asynchronous environment.[more]
Acoustic wave speed
The speed of sound in the pipe and fluid;also represents the speed at which a change in pressure can be transmitted within the system. [more]
Active
A state in which a metal tends to corrode; referring to the negative direction of electrode potential (opposite of passive or noble).[more]
Active corrosion
Continuing corrosion which, unless controlled, could result in a condition that is detrimental to public safety. [more]
Actuator
A device designed to shut off gas flow upon flame failure, pilot outage, control impulse, overpressure, or underpressure without a person being physically at the location. Valve actuators on mainline transmission systems are primarly operated by pushing a button at a control station.[more]
Adhesive joint
A joint made in plastic piping by the use of an adhesive substance which forms a bond between the mating surfaces without dissolving either one of them. [more]
Adjusting screw
A screw used to affect the compression setting of a loading spring.[more]
Administrator
The Administrator of the Pipeline and Hazardous Materials Safety Administration or any person to whom authority in the matter concerned has been delegated by the Secretary of Transportation.[more]
Aeration cell
"See Differential aeration cell." [more]
Aerosol Cloud
A mixture of gas vapor and drops of liquid that are so small they remain suspended in the vapor. Fog (water droplets suspended in air) is an example of an aerosol. Under some conditions, a release of LNG or flammable refrigerant may create an aerosol cloud. [more]
AGA
American Gas Association [more]
Air analyzer
An air analyzer is a device used to analyze air quality in and around personnel workspaces. It is used to detect such things as flammable vapor conditions (lower explosive limit (LEL)), poisonous hydrogen sulfide gas (H2S), carbon monoxide (CO), and any oxygen (O2) deficiency (19.5% or below) or enrichment (23.5% or above) in air.[more]
Alarm condition
A predefined change in the state or condition of equipment, or the failure of the equipment to respond correctly. Indication may be audible or visual or both. [more]
Alternating current (AC)
Alternating Current (AC): A current whose direction changes with time (e.g., commercial electricity used to run home appliances).[more]
Ambient temperature (AT)
The temperature of the environment surrounding a given point. For example, the air temperature reported by the weatherman is the ambient temperature of the air at the location of the instrument used to measure the air temperature. [more]
American National Standards Institute (ANSI)
A standards setting organization concerned with transmission codes and protocols.[more]
American Standards Association
In 1928 the American Engineering Standards Committee (AESC) became the American Standards Association. ASA was reorganized in 1966 and became the United States of American Standards Institute (USASI). The name ANSI was adopted in 1969.[more]
Amine
Amine is the common name for a family of chemicals that includes monoethanolamine (MEA), diethanolamine (DEA), and methyl diethanolamine (MDEA). Amines are used to remove carbon dioxide and hydrogen sulfide from natural gas. Natural gas is exposed to liquid amine in a contactor vessel, where carbon dioxide and hydrogen sulfide are absorbed by the amine. The contaminated amine is pumped to a regenerator where it is heated to remove the carbon dioxide and hydrogen sulfide. The regenerated liquid...[more]
Ampere
An ampere is a unit used to measure the rate of flow of electrical current. The unit was named after Andre Marie Ampere, a French physicist, for his discoveries in electrodynamics. The ampere unit was first defined as a current that occurs when 1 coulomb of electric charge flows past a given point of an electric circuit in one second and was later defined in terms of the current required to produce a certain amount of force between two wires. [more]
Amphoteric metal
A metal that is susceptible to corrosion in both acid and alkaline environments. Aluminum is an example of an amphoteric metal. [more]
Anaerobic
Free of air or uncombined oxygen. [more]
Analog
A transmission signal or system, such as the current telephone system, which varies in a continuous manner (waveform) as opposed to digitally. [more]
Analog device
A device that operates with variables represented by continuously measured quantities such as voltage, resistance, temperature, and pressure etc.[more]
Analog-to-digital conversion
Product of a digital signal whose magnitude is proportional to the value of an analog quantity. [more]
Anhydrous ammonia
A colorless gas with a pungent suffocating odor. It is shipped as a compressed gas, which is considered to be a hazardous liquid. Will burn skin if touched and can be deadly if inhaled. [more]
Anhydrous ammonia
A colorless gas with a pungent suffocating odor. It is shipped as a compressed gas, which is considered to be a hazardous liquid. Will burn skin if touched and can be deadly if inhaled.[more]
Annular space
The space between the cylindrical portions of the inner and outer walls of a double-wall tank. [more]
Anode
The electrode in a corrosion cell where oxidation or corrosion occurs. In a pipeline-related cathodic protection 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 types of anodes: the galvanic type and the impressed current type.[more]
Anode corrosion efficiency
Anode corrosion efficiency is the ratio of actual to theoretical corrosion based on the total current flow calculated by Faraday’s Law from the quantity of electricity that has passed.[more]
Anodeless riser
A steel casing with a plastic pipe inside. The plastic pipe inside the steel casing is the service line carrying gas to the customer meter.[more]
Anodic polarization
The change of the electrode potential in the noble (positive) direction caused by current across the electrode-to-electrolyte interface.[more]
ANPRM
Advance Notice of Proposed Rulemaking[more]
ANSI
American National Standards Institute[more]
Anti-rotation device
A stopping device that is commonly fastened to both the tank roof and floor. This device is rigid and often is constructed of pipe or cable. Anti-rotation devices are required in open and covered floaters to prevent rotation of floating roofs. [more]
APGA
American Public Gas Association[more]
API
American Petroleum Institute[more]
API gravity
A measure of the weight of a fluid at 60°F. API gravity is predominantly used to describe crude oils and petroleum products. [more]
Architecture
The physical inter relationship between the components of a computer system assessment The use of testing techniques as allowed in this subpart to ascertain the condition of a covered pipeline segment [more]
ASME
American Society of Mechanical Engineers[more]
ASNDT
American Society for Non-destructive Testing [more]
asphyxiant
A substance that depletes oxygen in the air, causing breathing difficulty for those persons in the vicinity. [more]
Assessment
The use of testing techniques as allowed in this subpart to ascertain the condition of a covered pipeline segment. [more]
Asynchronous
A transmission scheme that uses start/stop bits to define a character and separate it from other characters. Each character is sent to a central processor as it is typed. [more]
Atmosphere, atm
A measurement of pressure based upon the pressure due to the column of air above the earth's surface. One atm is equal to 14.7 psi. [more]
Atmospheric pressure
The pressure exerted by the atmosphere at a given location and time. Sea level pressure is approximately 14.7 PSI absolute.[more]
Atmospheric stability
Atmospheric stability is a measure of the vertical turbulence within the atmosphere near the earth's surface. The Pasquill-Gifford classification of atmospheric stability ranges from A to F, with A being the most unstable (most turbulent) and F being the most stable (least turbulent). Turbulence tends to increase the rate of mixing and dispersion, so unstable conditions promote short vapor clouds and stable conditions promote long vapor clouds. [more]
Atmospheric storage tank
These tanks are designed for pressures that are approximately equal to that of the atmosphere. [more]
Atomic number
The atomic number of an element is listed in the periodic table and refers to the number of protons or electrons that make up an atom of a given element. [more]
Atomic weight
The atomic weight of an element is listed in the periodic table and refers to the total number of protons and neutrons in the nucleus. [more]
Attenuation
Loss of power or signal energy that occurs during transmission over communication lines and equipment. [more]
Automated mapping/facilities management/geographic, AM/FM, interface
The ability to exchange data with automated mapping/facilities management/geographic information systems. This provides a mechanism for a SCADA system to automatically access data manually entered for other uses, such as plant drawings, location maps, and associated information.[more]
Automatic control
An arrangement of electric controls that provides for switching or controlling, or both of equipment in an automatic sequence and under predetermined conditions. [more]
Availability
The ratio of uptime to total time (uptime + downtime).[more]
AWS
American Welding Society[more]
BTS
Bureau of Transportation Statistics[more]
Capital Improvement
An expenditure for a physical improvement to an existing capital asset such as additions and major alterations that are intended to improve performance or increase useful life. [more]
CFR
Code of Federal Regulations [more]
CGA
Common Ground Alliance[more]
Compressed Gas
Material or mixture meeting criteria in § 173.115(b), (absolute pressure of 280 kPa [41 psia]) at 20°C [68° F] or greater).[more]
COOQ
Consortium on Operator Qualification[more]
CP
Cathodic Protection[more]
CPM
Computational Pipeline Monitoring[more]
CSA
Canadian Standards Association[more]
D/t or d/t
Ration or diameter to thickness, usually of a pipe.[more]
DCA
Distribution Contractors Association[more]
DMS
Docket Management System (historical system used by DOT prior to the Federal Docket Management System (FDMS)). [more]
DOT
U.S. Department of Transportation[more]
Easement
A right-of-way agreement between the pipeline company and the property owner is also called an easement and is usually filed in the public records with property deeds. A pipeline right-of-way is a strip of land over and around pipelines where some of the property owner's legal rights have been granted to a pipeline company. Rights-of-ways and easements provide a permanent, limited interest in the land that enables the pipeline company to operate, test, inspect, repair, maintain, replace, and...[more]
Emergency Response Information
Information that can be used in the mitigation of an incident involving hazardous materials.[more]
ETN
Midwest Energy Assocaition (MEA)/Energy Training Network (ETN)[more]
FBE
Fusion Bonded Epoxy[more]
FDMS
Federal Docket Management System. This system houses current dockets.[more]
FERC
Federal Energy Regulatory Commission[more]
FOIA
Freedom of Information Act[more]
Forbidden
A material that is prohibited from being offered or accepted for transportation. This prohibition does not apply if these materials are: [more]
FR
Used as both Federal Register and Final Rule[more]
FTE
Full-time Equivalent[more]
GAO
Gneral Accountability Office (formerly General Accounting Office)[more]
GPO
Government Printing Office[more]
GPTC
Gas Piping Technology Committee[more]
GRI
Now GTI (Gas Technology Institute)[more]
GTI
Gas Technology Institute (formerly GRI)[more]
IBR
Incorporated by Reference; refers to incorporateion of technical standards documents into the pipeline safety regulations by reference.[more]
Identification Number (ID No.)
The UN or NA “four-digit number” assigned to hazardous materials, i.e., UN 1203. ID numbers are listed in Col. 4 of the HMT. Used for identification and emergency response.[more]
IG
Office of the Inspector General (also referred to as "OIG"), commonly the office of any Agency which performs these duties. In most documents presented here, assume the Department of Transportation OIG unless otherwise stated.[more]
INGAA
Interstate Natural Gas Association of America[more]
Irritating Material
A liquid or solid substance. Upon contact with fire or air, the material gives off dangerous or intensely irritating fumes. [more]
ISO
International Standards Organization[more]
LP
Liquefied Petroleum[more]
MEA
Midwest Energy Assocaition (MEA)/Energy Training Network (ETN)[more]
MSS
Manufactures Standardization Society of the Valve and Fitting Industry[more]
NACE
National Association of Corrosion Engineers[more]
NAPSR
National Association of Pipeline Safety Representatives[more]
NARUC
National Association of Regulatory Utility Commissioners[more]
NCCER
National Center for Construction Education and Research[more]
NFPA
National Fire Protection Association[more]
NGA
National Gas Association[more]
NIST
National Institue of Standards and Technology[more]
NOI
Notice of Inquiry[more]
NPGA
National Propane Gas Association[more]
NPRM
Notice of Proposed Rule Making[more]
NTSB
National Transportation Safety Board[more]
NUCA
National Utility Contractors Association[more]
NULCA
National Utility Locating Contractors Association[more]
OFR
Office of the Federal Register[more]
OIG
Office of the Inspector General (also referred to as "IG"), commonly the office of any Agency which performs these duties. In most documents presented here, assume the Department of Transportation OIG unless otherwise stated.[more]
OMB
Office of Management and Budget[more]
OQ
Operator Qualification, the act or method for a pipeline operator to become qualified.[more]
OQSG
OQ Solutions Group[more]
OSHA (Act)
Occupational Safety and Health Act[more]
OSHA (Administration)
Occupational Safety and Health Administration[more]
P.L.
Public Law[more]
PERC
Propane Education and Research Council[more]
PPDC
Plastic Pipe Database Committee[more]
PPI
Plastic Pipe Institute[more]
PRCI
Pipeline Research Council International[more]
PSIA
Pipeline Safety Improvement Act[more]
Right-of-way
A pipeline right-of-way is a strip of land over and around pipelines where some of the property owner's legal rights have been granted to a pipeline company. A right-of-way agreement between the pipeline company and the property owner is also called an easement and is usually filed in the public records with property deeds. Rights-of-ways and easements provide a permanent, limited interest in the land that enables the pipeline company to operate, test, inspect, repair, maintain, replace, and...[more]
RITA
Research and Innovative Technology Administration (of the U.S. Department of Transportation)[more]
SGA
Southern Gas Association[more]
SNPRM
Supplemental Notice of Proposed Rulemaking[more]
SWG
Sothwest Gas Corporation[more]
TIC
Trenchless Information Center[more]
TPSSC
Technical Pipeline Safety Standards Committee [more]
TSI
Transportation Safety Institute[more]
U.S.C.
United States Code[more]
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