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25 Pa. Code § 129.122. Definitions, acronyms and EPA methods.

§ 129.122. Definitions, acronyms and EPA methods.

 (a)  Definitions and acronyms. The following words and terms, when used in this section, § §  129.121 (relating to general provisions and applicability) and 129.123—129.130, have the following meanings, unless the context clearly indicates otherwise:

   AVO—Audible, visual and olfactory.

   Bleed rate—The rate in standard cubic feet per hour at which natural gas is continuously vented from a natural gas-driven continuous bleed pneumatic controller.

   Centrifugal compressor

     (i)   A machine for raising the pressure of natural gas by drawing in low-pressure natural gas and discharging significantly higher-pressure natural gas by means of mechanical rotating vanes or impellers.

     (ii)   The term does not include a screw compressor, sliding vane compressor or liquid ring compressor.

   Closed vent system—A system that is not open to the atmosphere and that is composed of hard-piping, ductwork, connections and, if necessary, flow-inducing devices that transport gas or vapor from a piece or pieces of equipment to a control device or back to a process.

   Condensate—Hydrocarbon liquid separated from natural gas that condenses due to changes in the temperature, pressure, or both, and remains liquid at standard conditions.


     (i)   A flanged fitting, screwed fitting or other joined fitting used to connect two pipes or a pipe and a piece of process equipment or that closes an opening in a pipe that could be connected to another pipe.

     (ii)   The term does not include a joined fitting welded completely around the circumference of the interface.

   Control device—An enclosed combustion device, vapor recovery system or flare.

   Custody transfer—The transfer of natural gas after processing or treatment, or both, in the producing operation or from a storage vessel or an automatic transfer facility or other equipment, including a product loading rack, to a pipeline or another form of transportation.

   Deviation—An instance in which the owner or operator of a source subject to this section, § §  129.121 and 129.123—129.130 fails to meet one or more of the following:

     (i)   A requirement or an obligation established in this section, §  129.121 or § §  129.123—129.130, including an emission limit, operating limit or work practice standard.

     (ii)   A term or condition that is adopted to implement an applicable requirement in this section, §  129.121 or § §  129.123—129.130 and which is included in the operating permit for the affected source.

     (iii)   An emission limit, operating limit or work practice standard in this section, §  129.121 or § §  129.123—129.130 during startup, shutdown or malfunction, regardless of whether a failure is permitted by this section, §  129.121 or § §  129.123—129.130.

   FID—Flame ionization detector.

   First attempt at repair—For purposes of §  129.127 (relating to fugitive emissions components):

     (i)   An action using best practices taken to stop or reduce fugitive emissions to the atmosphere.

     (ii)   The term includes:

       (A)   Tightening bonnet bolts.

       (B)   Replacing bonnet bolts.

       (C)   Tightening packing gland nuts.

       (D)   Injecting lubricant into lubricated packing.


     (i)   A thermal oxidation system using an open flame without an enclosure.

     (ii)   The term does not include a horizontally or vertically installed ignition device or pit flare used to combust otherwise vented emissions from completions.

   Flow line—A pipeline used to transport oil or gas, or both, to processing equipment, compression equipment, storage vessel or other collection system for further handling or to a mainline pipeline.

   Fugitive emissions component

     (i)   A piece of equipment that has the potential to emit fugitive emissions of VOC at a well site, a gathering and boosting station or a natural gas processing plant, including the following:

       (A)   A valve.

       (B)   A connector.

       (C)   A pressure relief device.

       (D)   An open-ended line.

       (E)   A flange.

       (F)   A compressor.

       (G)   An instrument.

       (H)   A meter.

       (I)   A cover or closed vent system not subject to §  129.128 (relating to covers and closed vent systems).

       (J)   A thief hatch or other opening on a controlled storage vessel not subject to §  129.123 (relating to storage vessels).

     (ii)   The term does not include a device, such as a natural gas-driven continuous bleed pneumatic controller or a natural gas-driven diaphragm pump, that vents as part of normal operations if the gas is discharged from the device’s vent.

   GOR—gas-to-oil ratio—The ratio of the volume of gas at standard temperature and pressure that is produced from a volume of oil when depressurized to standard temperature and pressure.

   Gathering and boosting station

     (i)   A permanent combination of one or more compressors that collects natural gas from one or more well sites and moves the natural gas at increased pressure into a gathering pipeline to the natural gas processing plant or into the pipeline.

     (ii)   The term does not include the combination of one or more compressors located at a well site or located at an onshore natural gas processing plant.

   Hard-piping—Pipe or tubing that is manufactured and properly installed using good engineering judgment and standards.

   Hydraulic fracturing—The process of directing pressurized fluids containing a combination of water, proppant and added chemicals to penetrate tight formations, such as shale or coal formations, that subsequently require high rate, extended flowback to expel fracture fluids and solids during a completion.

   Hydraulic refracturing—Conducting a subsequent hydraulic fracturing operation at a well that has previously undergone a hydraulic fracturing operation.

   In-house engineer—An individual who is both of the following:

     (i)   Employed by the same owner or operator as the responsible official that signs the certification required under §  129.130(k) (relating to recordkeeping and reporting).

     (ii)   Qualified by education, technical knowledge and expertise in the design and operation of a natural gas-driven diaphragm pump or closed vent system to make the technical certification required under §  129.125(c)(3)(ii) (relating to natural gas-driven diaphragm pumps) or §  129.128(c)(3), or both, as applicable.

   Intermediate hydrocarbon liquid—A naturally occurring, unrefined petroleum liquid.

   LDAR—Leak detection and repair.

   Leak—An emission detected using one or more of the following methods:

     (i)   Through audible, visual or odorous evidence during an AVO inspection.

     (ii)   By OGI equipment calibrated according to §  129.127(h) (relating to fugitive emissions components).

     (iii)   With a concentration of 500 ppm or greater as methane or equivalent by a gas leak detector calibrated according to §  129.127(i).

     (iv)   Using an alternative leak detection method approved by the Department in §  129.127(c)(2)(ii)(C), (c)(3)(ii)(C) or (e)(2)(iii).

   Maximum average daily throughput—The single highest daily average throughput during the 30-day potential to emit evaluation period employing generally accepted methods.

   Monitoring system malfunction

     (i)   A sudden, infrequent, not reasonably preventable failure of the monitoring system to provide valid data.

     (ii)   The term does not include a system failure caused by poor maintenance or careless operation.

   Natural gas distribution segment—The delivery of natural gas to the end user by a distribution company after the distribution company receives the natural gas from the natural gas transmission and storage segment.

   Natural gas-driven diaphragm pump

     (i)   A positive displacement pump powered by pressurized natural gas that uses the reciprocating action of flexible diaphragms in conjunction with check valves to pump a fluid.

     (ii)   The term does not include either of the following:

       (A)   A pump in which a fluid is displaced by a piston driven by a diaphragm.

       (B)   A lean glycol circulation pump that relies on energy exchange with the rich glycol from the contactor.

   Natural gas-driven continuous bleed pneumatic controller—An automated instrument used for maintaining a process condition such as liquid level, pressure, delta-pressure or temperature powered by a continuous flow of pressurized natural gas.

   Natural gas liquids—The hydrocarbons, such as ethane, propane, butane and pentane, that are extracted from field gas.

   Natural gas processing plant

     (i)   A processing site engaged in the extraction of natural gas liquids from field gas, fractionation of mixed natural gas liquids to natural gas products, or both.

     (ii)   The term does not include a Joule-Thompson valve, a dew point depression valve or an isolated or standalone Joule-Thompson skid.

   Natural gas transmission and storage segment—The term includes the following:

     (i)   The pipelines used for the long-distance transport of natural gas, excluding processing.

     (ii)   The natural gas transmission stations which include the following:

       (A)   The land, mains, valves, meters, boosters, regulators, storage vessels, dehydrators and compressors.

       (B)   The driving units and appurtenances associated with the items listed in clause (A).

       (C)   The equipment used for transporting gas from a production plant, delivery point of purchased gas, gathering system, storage area or other wholesale source of gas to one or more distribution areas.

     (iii)   The aboveground storage facilities and underground storage facilities that transport and store natural gas between the natural gas processing plant and natural gas distribution segment.

   OGI—Optical gas imaging.

   Open-ended valve or line—A valve, except a safety relief valve, having one side of the valve seat in contact with process fluid and one side open to the atmosphere, either directly or through open piping.

   Produced water—Water that is extracted from the earth from an oil or natural gas production well or that is separated from crude oil, condensate or natural gas after extraction.

   Qualified professional engineer

     (i)   An individual who is licensed by a state as a Professional Engineer to practice one or more disciplines of engineering and who is qualified by education, technical knowledge and experience to make the required specific technical certification.

     (ii)   The individual making this certification must be currently licensed in this Commonwealth or another state in which the responsible official, as defined in §  121.1 (relating to definitions), is located and with which the Commonwealth offers reciprocity.

   Quality assurance or quality control activity—An activity such as a system accuracy audit and a zero and span adjustment that ensures the proper calibration and operation of monitoring equipment.

   Reciprocating compressor—A piece of equipment that employs linear movement of a driveshaft to increase the pressure of a process gas by positive displacement.

   Reciprocating compressor rod packing

     (i)   A series of flexible rings in machined metal cups that fit around the reciprocating compressor piston rod to create a seal limiting the amount of compressed natural gas that escapes to the atmosphere.

     (ii)   Another mechanism that provides the same function.

   Removed from service—A storage vessel that has been physically isolated and disconnected from the process for a purpose other than maintenance.

   Repaired—A piece of equipment that is adjusted or otherwise altered to eliminate a leak and is remonitored to verify that emissions from the equipment are at or below the applicable leak limitation.

   Returned to service—A storage vessel that was removed from service which has been:

     (i)   Reconnected to the original source of liquids or has been used to replace another storage vessel.

     (ii)   Installed in another location and introduced with crude oil, condensate, intermediate hydrocarbon liquids or produced water.

   Routed to a process or route to a process—The emissions are conveyed by means of a closed vent system to an enclosed portion of a process that is operational where the emissions are controlled in one or more of the following ways:

     (i)   Predominantly recycled or consumed, or both, in the same manner as a material that fulfills the same function in the process.

     (ii)   Transformed by chemical reaction into materials that are not regulated.

     (iii)   Incorporated into a product.

     (iv)   Recovered for beneficial use.

   Sensor—A device that measures a physical quantity or the change in a physical quantity such as temperature, pressure, flow rate, pH or liquid level.

   Storage vessel

     (i)   A container used to collect crude oil, condensate, intermediate hydrocarbon liquids or produced water that is constructed primarily of non-earthen materials which provide structural support.

     (ii)   The term includes a container described in subparagraph (i) that is skid-mounted or permanently attached to something that is mobile which has been located at a site for 180 or more consecutive days.

     (iii)   The term does not include the following:

       (A)   A process vessel such as a surge control vessel, bottoms receiver or knockout vessel.

       (B)   A pressure vessel used to store a liquid or a gas and is designed to operate in excess of 204.9 kilopascals (29.7 pounds per square inch, absolute) and to not vent to the atmosphere as a result of compression of the vapor headspace during filling of the vessel.

       (C)   A container described in subparagraph (i) with a capacity greater than 100,000 gallons used to recycle water that has been passed through two-stage separation.

   Surface site—A combination of one or more graded pad sites, gravel pad sites, foundations, platforms or the immediate physical location upon which equipment is physically affixed.

   TOCtotal organic compounds—The results of EPA Method 25A.

   UIC—Underground injection control.

   UIC Class I oilfield disposal well—A well with a UIC Class I permit that meets the definition in 40 CFR 144.6(a)(2) (relating to classification of wells) and receives eligible fluids from oil and natural gas exploration and production operations.

   UIC Class II oilfield disposal well—A well with a UIC Class II permit where wastewater resulting from oil and natural gas production operations is injected into underground porous rock formations not productive of oil or gas and sealed above and below by unbroken, impermeable strata.

   Unconventional formation—A geological shale formation existing below the base of the Elk Sandstone or its geologic equivalent stratigraphic interval where natural gas generally cannot be produced at economic flow rates or in economic volumes except by vertical or horizontal well bores stimulated by hydraulic fracture treatments or by using multilateral well bores or other techniques to expose more of the formation to the well bore.

   Unconventional well—A bore hole drilled or being drilled for the purpose of or to be used for the production of natural gas from an unconventional formation.

   Unconventional well site—A location with one or more unconventional wells.

   VRU—vapor recovery unit—A device used to recover vapor and route it to a process, flow line or other equipment.

   Well—A hole drilled for producing oil or natural gas or into which a fluid is injected.


     (i)   The piping, casing, tubing and connected valves protruding above the earth’s surface for an oil or natural gas well.

     (ii)   The wellhead ends where the flow line connects to a wellhead valve.

     (iii)   The term does not include other equipment at the well site except for a conveyance through which gas is vented to the atmosphere.

   Well site

     (i)   One or more surface sites that are constructed for the drilling and subsequent operation of an unconventional well or injection well.

     (ii)   For purposes of the fugitive emissions standards in §  129.127, the term also means a separate tank battery surface site collecting crude oil, condensate, intermediate hydrocarbon liquids or produced water from a well not located at the well site, for example, a centralized tank battery.

     (iii)   For purposes of the fugitive emissions standards in §  129.127, the term does not include:

       (A)   A UIC Class I oilfield disposal well.

       (B)   A UIC Class II oilfield disposal well and disposal facility.

       (C)   The flange immediately upstream of the custody meter assembly.

       (D)   Equipment, including fugitive emissions components, located downstream of the flange in clause (C).

 (b)  EPA methods. The EPA methods referenced in this section and § §  129.123—129.130 are those listed as follows, unless the context clearly indicates otherwise:

   EPA Method 1—EPA Method 1, 40 CFR Part 60, Appendix A-1 (relating to test methods 1 through 2F), regarding sample and velocity traverses for stationary sources.

   EPA Method 1A—EPA Method 1A, 40 CFR Part 60, Appendix A-1, regarding sample and velocity traverses for stationary sources with small stacks or ducts.

   EPA Method 2—EPA Method 2, 40 CFR Part 60, Appendix A-1, regarding determination of stack gas velocity and volumetric flow rate (Type S pitot tube).

   EPA Method 2A—EPA Method 2A, 40 CFR Part 60, Appendix A-1, regarding direct measurement of gas volume through pipes and small ducts.

   EPA Method 2C—EPA Method 2C, 40 CFR Part 60, Appendix A-1, regarding determination of gas velocity and volumetric flow rate in small stacks or ducts (standard pitot tube).

   EPA Method 2D—EPA Method 2D, 40 CFR Part 60, Appendix A-1, regarding measurement of gas volume flow rates in small pipes and ducts.

   EPA Method 3A—EPA Method 3A, 40 CFR Part 60, Appendix A-2 (relating to test methods 2G through 3C), regarding determination of oxygen and carbon dioxide concentrations in emissions from stationary sources (instrumental analyzer procedure).

   EPA Method 3B—EPA Method 3B, 40 CFR Part 60, Appendix A-2, regarding gas analysis for the determination of emission rate correction factor or excess air.

   EPA Method 4—EPA Method 4, 40 CFR Part 60, Appendix A-3 (relating to test methods 4 through 5I), regarding determination of moisture content in stack gases.

   EPA Method 18—EPA Method 18, 40 CFR Part 60, Appendix A-6 (relating to test methods 16 through 18), regarding measurement of gaseous organic compound emissions by gas chromatography.

   EPA Method 21—EPA Method 21, 40 CFR Part 60, Appendix A-7 (relating to test methods 19 through 25E), regarding determination of volatile organic compound leaks.

   EPA Method 22—EPA Method 22, 40 CFR Part 60, Appendix A-7, regarding visual determination of fugitive emissions from material sources and smoke emissions from flares.

   EPA Method 25A—EPA Method 25A, 40 CFR Part 60, Appendix A-7, regarding determination of total gaseous organic concentration using a flame ionization analyzer.


   The provisions of this §  129.122 added under section 5(a)(1) and (8) of the Air Pollution Act (35 P.S. §  4005(a)(1) and (8)).


   The provisions of this §  129.122 added December 9, 2022, effective December 10, 2022, 52 Pa.B. 7587.

Cross References

   This section cited in 25 Pa. Code §  129.121 (relating to general provisions and applicability); 25 Pa. Code §  129.123 (relating to storage vessels); 25 Pa. Code §  129.127 (relating to fugitive emissions components); 25 Pa. Code §  129.128 (relating to covers and closed vent systems); and 25 Pa. Code §  129.130 (relating to recordkeeping and reporting).

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