(a) Applicability. Except as specified in §115.547 of this title (relating to Exemptions), this division applies to degassing during, or in preparation of, cleaning any storage tank, transport vessel, or marine vessel containing volatile organic compounds with a true vapor pressure greater than or equal to 0.5 pounds per square inch absolute under actual storage conditions. In this division, the operator of any storage tank, transport vessel, or marine vessel refers to the regulated entity performing or outsourcing the degassing operation.
  (1) In the Beaumont-Port Arthur area, as defined in §115.10 of this title (relating to Definitions), this division applies to any storage tank, transport vessel, or marine vessel.
  (2) In the Dallas-Fort Worth area, as defined in §115.10 of this title, this division applies to any storage tank or transport vessel in Collin, Dallas, Denton, and Tarrant Counties. This division does not apply to any tank or vessel in Ellis, Johnson, Kaufman, Parker, or Rockwall Counties.
  (3) In the El Paso area, as defined in §115.10 of this title, this division applies to any storage tank or transport vessel.
  (4) In the Houston-Galveston-Brazoria area, as defined in §115.10 of this title, this division applies to any storage tank, transport vessel, or marine vessel.
(b) 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), the terms in this division have the meanings commonly used in the field of air pollution control. In addition, the following meanings apply in this division unless the context clearly indicates otherwise.
  (1) Cleaning--The process of washing or rinsing a storage tank, transport vessel, or marine vessel, or removing sludge or rinsing liquid from a storage tank, transport vessel, or marine vessel.
  (2) Degassing--The process of removing volatile organic compounds vapor from a storage tank, transport vessel, or marine vessel during, or in preparation of, cleaning.
  (3) Drain-dry floating roof tank--A floating roof tank designed to completely drain its entire contents to a sump in a manner that leaves no free-standing liquid in the tank or the sump.
  (4) Recirculation system--A vapor-tight system that is composed of piping, ductwork, connections, flow inducing devices, and a control device. The recirculation system conducts volatile organic compounds vapor from a storage tank, transport vessel, or marine vessel to a control device and conducts the exhaust from the outlet of the control device back into the same tank or vessel. The recirculation system does not include the storage tank, transport vessel, or marine vessel that is being degassed.
  (5) Storage capacity--The volume of a storage tank as determined by multiplying the internal cross-sectional area of the tank by the average internal height of the tank shell or the volume of a transport vessel or marine vessel as determined by the manufacturer's original design capacity.
  (6) Storage tank--A stationary vessel, reservoir, or container used to store volatile organic compounds. This definition does not include: components that are not directly involved in the containment of liquids or vapors; subsurface caverns or porous rock reservoirs; or process tanks or vessels.
  (7) Vapor-tight--A condition that exists when no component of a system has a leak greater than 500 parts per million expressed as methane measured using Method 21 (40 Code of Federal Regulations Part 60, Appendix A-7).

Source Note: The provisions of this §115.540 adopted to be effective February 17, 2011 36 TexReg 807