SECTION 115.171. Definitions

Unless specifically defined in the Texas Clean Air Act (Texas Health and Safety Code, Chapter 382) or in §§3.2, 101.1, or 115.10 of this title (relating to Definitions, respectively), the terms in this division have the meanings commonly used in the field of air pollution control. The following meanings apply in this division unless the context clearly indicates otherwise.

(1) Centrifugal compressor--A piece of equipment 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. Screw, sliding vane, and liquid ring compressors are not centrifugal compressors.

(2) Closure device--A piece of equipment that covers an opening in the roof of a fixed roof storage tank and either can be temporarily opened or has a component that provides a temporary opening. Examples of closure devices include, but are not limited to, thief hatches, pressure relief valves, pressure-vacuum relief valves, and access hatches.

(3) Difficult-to-monitor--Equipment that cannot be inspected without elevating the inspecting personnel more than two meters above a support surface.

(4) Fugitive emission components--Except for vents as defined in §101.1 of this title (relating to Definitions) and sampling systems, equipment as defined in subparagraphs (A) and (B) of this paragraph that has the potential to leak volatile organic compounds (VOC) emissions.

(A) At a natural gas processing plant, equipment considered fugitive components include, but are not limited to, any pump, pressure relief device, open-ended valve or line, valve, flange, or other connector that is in VOC service or wet gas service, and any closed vent system or control device not subject to another section in this division that specifies one or more instrument monitoring requirements for the system or device. A compressor or sampling connection system that is exempt from the fugitive monitoring requirements in §115.352 and §115.354 of this title (relating to Fugitive Emission Control in Petroleum Refining, Natural Gas/Gasoline Processing, and Petrochemical Processes in Ozone Nonattainment Areas) on or before December 31, 2022 is excluded as a fugitive monitoring component under this subparagraph.

(B) At a well site or gathering and boosting station from equipment considered fugitive emissions components include, but are not limited to, valves, compressors, connectors, pressure relief devices, open-ended lines, flanges, instruments, meters, or other openings that are not on a storage tank subject to §115.175 of this title (relating to Storage Tank Control Requirements), and any closed vent system or control device not subject to another section in this division that specifies one or more instrument monitoring requirements for the system or device. A compressor seal at a gathering and boosting station that is addressed in §115.173 of this title (relating to Compressor Control Requirements) is not included as a fugitive emission component.

(5) Gathering and boosting station--Any permanent combination of one or more compressors that collects natural gas from well sites and moves the natural gas at increased pressure into gathering pipelines to a natural gas processing plant or into the pipeline. The combination of one or more compressors located at a well site, or located at an onshore natural gas processing plant, is not a gathering and boosting station.

(6) Heavy liquid service--An equipment is in heavy liquid service if the weight percent evaporated is 10.0% or less at 302 degrees Fahrenheit (150 degrees Celsius) as determined by ASTM Method D86-96.

(7) Light liquid service--A piece of equipment contains a liquid that meets the following conditions.

(A) The vapor pressure of one or more of the organic components is greater than 1.2 inches water at 68 degrees Fahrenheit (0.3 kilopascals at 20 degrees Celsius).

(B) The total concentration of the pure organic components having a vapor pressure greater than 1.2 inches water at 68 degrees Fahrenheit (0.3 kilopascals at 20 degrees Celsius) is equal to or greater than 20.0% by weight.

(C) The fluid is a liquid at operating conditions.

(D) An equipment is in light liquid service if the weight percent evaporated is greater than 10.0% at 302 degrees Fahrenheit (150 degrees Celsius) as determined by ASTM Method D86-96.

(8) Natural gas processing plant--any 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. A Joule-Thompson valve, a dew point depression valve, or an isolated or standalone Joule-Thompson skid is not a natural gas processing plant.

(9) Pneumatic controller--An automated instrument that is actuated by a compressed gas and is used to maintain a process condition such as liquid level, pressure, pressure differential and temperature. When actuated by natural gas, pneumatic controllers are characterized primarily by their emission characteristics.

(A) Continuous bleed pneumatic controllers receive a continuous flow of pneumatic natural gas supply and are used to modulate flow, liquid level, or pressure. Gas is vented continuously at a rate that may vary over time. Continuous bleed controllers are further subdivided into two types based on their bleed rate, which for the purposes of this section means the rate at which natural gas is continuously vented from a pneumatic controller and measured in standard cubic feet per hour (scfh):

(i) low bleed controllers have a bleed rate of less than or equal to 6.0 scfh; and

(ii) high bleed controllers have a bleed rate of greater than 6.0 scfh.

(B) Intermittent bleed or snap-acting pneumatic controllers release natural gas only when they open or close a valve or as they throttle the gas flow.

(C) Zero-bleed pneumatic controllers do not bleed natural gas to the atmosphere. These pneumatic controllers are self-contained devices that release gas to a downstream pipeline instead of to the atmosphere.

(10) Pneumatic pump--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.

(11) Reciprocating compressor--A piece of equipment that increases the pressure of a natural gas by positive displacement, employing linear movement of the driveshaft.

(12) Rod packing--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, or other mechanism that provides the same function.

(13) Route to a process--The emissions are:

(A) conveyed via a closed vent system to any enclosed portion of a process where it is predominantly recycled or consumed in the same manner as a material that fulfills the same function in the process or is transformed by chemical reaction into materials that are not regulated materials or incorporated into a product; or

(B) recovered.

(14) Storage tank--A tank, stationary vessel, or a container that contains an accumulation of crude oil, condensate, intermediate hydrocarbon liquids, or produced water, and that is constructed primarily of non-earthen materials.

(15) Unsafe-to-monitor--Equipment that exposes monitoring personnel to an imminent or potential danger as a consequence of conducting an inspection.

(16) Vapor recovery unit--A device that transfers hydrocarbon vapors to a fuel liquid or gas system, a sales liquid or gas system, or a liquid storage tank.

(17) Well site--A parcel of land with one or more surface sites, which means sites with any combination of one or more graded pad sites, gravel pad sites, foundations, platforms, or the immediate physical location upon which equipment is physically affixed, that are constructed for the drilling and subsequent operation of one or more oil, natural gas, or injection wells. The meaning of "site" and "sites" in this definition is limited to this division.

(18) Wet gas service--A piece of equipment which contains or contacts the field gas before the extraction step at a gas processing plant process unit.

Source Note: The provisions of this §115.171 adopted to be effective July 21, 2021, 46 TexReg 4313