SECTION 115.175. Storage Tank Control Requirements

(a) No person shall place, store, or hold crude oil or condensate in any storage tank unless the tank is capable of maintaining working pressure sufficient at all times to prevent any vapor or gas loss to the atmosphere or is in compliance with the following controls.

(1) All openings in a fixed roof storage tank through which vapors are not routed to a vapor recovery unit or other control device specified in paragraph (2) of this subsection, must be equipped with a closure device maintained according to the manufacturer's instructions and operated according to this paragraph. If manufacturer instructions are unavailable, industry standards consistent with good engineering practice can be substituted.

(A) Each closure device must be closed at all times except when normally actuated or required to be open for temporary access or to relieve excess pressure or vacuum in accordance with the manufacturer's design and consistent with good air pollution control practices. Such opening, actuation, or use must be limited to minimize vapor loss.

(B) Each closure device must be properly sealed to minimize vapor loss and must form a continuous impermeable barrier over the entire surface area of the liquid in the storage tank when closed.

(C) Each closure device must either be latched closed or, if designed to relieve pressure, set to automatically open at a pressure that will ensure all vapors are routed to the vapor recovery unit or other control device under normal operating conditions other than gauging the tank or taking a sample through an open thief hatch.

(D) No closure device may be allowed to have a volatile organic compound (VOC) leak for more than 15 calendar days after the leak is found unless delay of repair is allowed. For the purposes of this subparagraph, a leak is the exuding of process gasses from a closed device detected by audio, visual, and olfactory means. If parts are unavailable, repair may be delayed. Parts must be ordered promptly, and the repair must be completed within five days of receipt of required parts. Repair may be delayed until the next shutdown if the repair of the component would require a shutdown that would create more emissions than the repair would eliminate. Repair must be completed by the end of the next shutdown.

(2) A control device used to comply with this subsection must meet one of the following conditions at all times when VOC vapors are routed to the device. The VOC vapors must be routed through a closed vent system that must be designed and operated to route to a control device, including to route to a process, all captured VOC vapor . Multiple vents may be routed to the same control device. Control devices and closed vent systems must comply with the requirements of §115.178 of this title (relating to Monitoring and Inspection Requirements) and §115.179 of this title (relating to Approved Test Methods and Testing Requirements).

(A) A control device, other than a device specified in subparagraphs (B) and (C) of this paragraph, to which VOC vapors are routed, must maintain a control efficiency of at least 95% or a VOC concentration of equal to or less than 275 parts per million by volume (ppmv), as propane, on a wet basis corrected to 3% oxygen. The 95% VOC control efficiency and 275 ppmv VOC concentration are calculated from the gas stream at the control device outlet. For a boiler or process heater used as the control device, the vent gas stream must be introduced into the flame zone of the boiler or process heater.

(B) A flare must be designed and operated in accordance with 40 Code of Federal Regulations (CFR) §60.18(b) - (f) (as amended through December 22, 2008 (73 FR 78209)). The flare must be lit at all times when VOC vapors are routed to the flare.

(C) A vapor recovery unit must be designed to process all vapor generated by the maximum liquid throughput of the storage tank or the aggregate of storage tanks in a tank battery and must transfer recovered vapors to a pipe or container that is vapor-tight, as defined in §115.10 of this title (relating to Definitions).

(D) A control device, used to comply with subparagraph (A) of this paragraph, must operate with no visible emissions, as determined through a visible emissions test conducted according to United States Environmental Protection Agency (EPA) Method 22, 40 CFR Part 60, Appendix A-7, Section 11 (as amended March 16, 2015 (83 FR 13751)), except for periods not to exceed a total of one minute during any 15-minute observation period.

(3) Beginning on the appropriate compliance date in §115.183 of this title (relating to Compliance Schedules), any storage tank that stores crude oil or condensate with a true vapor pressure of greater than or equal to 11 pounds per square inch absolute (psia) and a storage capacity of at least 40,000 gallons, and was required to use a submerged fill pipe under Table 2 in §115.112(e)(1) of this title (relating to Control Requirements), must continue to use a submerged fill pipe.

(4) The following requirements apply to a bypass installed on a closed vent system able to divert any portion of the flow from entering a control device or routing to a process.

(A) A flow indicator must be installed, calibrated, and maintained at the inlet of each bypass. The flow indicator must take a reading at least once every 15 minutes and initiate an alarm notifying operators to take prompt remedial action when bypass flows are present.

(B) Each bypass valve must be secured in the non-diverting position using a car-seal or a lock-and-key type configuration.

(b) Any storage tank with the potential to emit less than 6.0 tons per year of VOC, and any storage tank with the potential to emit at least 6.0 tons per year of VOC emissions but that demonstrates uncontrolled actual VOC emissions are less than 4.0 tons per year, is not required to be in compliance with the control requirements in subsection (a) of this section unless the tank was required to comply with a control requirement in §115.112(e) of this title on or before December 31, 2022. The owner or operator shall continue to comply with the control requirement that applied as of December 31, 2022 in the Table in §115.112(e) of this title. The calculation of emissions demonstrating that actual VOC emissions are less than 4.0 tons per year for 12 consecutive months based on average monthly throughput must be performed on a monthly basis.

Attached Graphic

(c) The owner or operator shall calculate VOC emissions as follows.

(1) Uncontrolled VOC emissions for a fixed roof storage tank must be estimated using the highest 12 consecutive months out of the last five years of production data for the initial determination in accordance with the appropriate compliance date in §115.183 of this title, and one of the following methods. However, if emissions determined using direct measurements or other methods approved by the executive director under subparagraph (A) or (B) of this paragraph are higher than emissions estimated using the default factors or charts in subparagraph (C) or (D) of this paragraph, the higher values must be used.

(A) The owner or operator may make direct measurements using the measuring instruments and methods specified in §115.179 of this title.

(B) The owner or operator may use other test methods or computer simulations approved by the executive director.

(C) The owner or operator may use a factor of 33.3 pounds of VOC per barrel (42 gallons) of condensate produced or 1.6 pounds of VOC per barrel (42 gallons) of oil produced.

(D) For crude oil storage only, the owner or operator may use the chart in Exhibit 2 of the EPA's Lessons Learned from Natural Gas Star Partners: Installing Vapor Recovery Units on Crude Oil Storage Tanks, October 2003, and assuming that the hydrocarbon vapors have a molecular weight of 34 pounds per pound mole and are 48% by weight VOC.

(2) The VOC potential to emit must be based on the maximum average daily throughput determined for a 30-day period of production prior to the appropriate compliance date listed in §115.183 of this title.

(d) For an external floating roof or internal floating roof storage tank, the following requirements apply.

(1) All openings in an internal floating roof or external floating roof must provide a projection below the liquid surface. Automatic bleeder vents (vacuum breaker vents) and rim space vents are not subject to this requirement.

(2) All openings in an internal floating roof or external floating roof must be equipped with a deck cover. The deck cover must be equipped with a gasket in good operating condition between the cover and the deck. The deck cover must be closed (i.e., no gap of more than 1/8 inch) at all times, except when the cover must be open for access. Automatic bleeder vents (vacuum breaker vents), rim space vents, leg sleeves, and roof drains are not subject to this requirement.

(3) Automatic bleeder vents (vacuum breaker vents) and rim space vents must be equipped with a gasketed lid, pallet, flapper, or other closure device and must be closed (i.e., no gap of more than 1/8 inch) at all times except when required to be open to relieve excess pressure or vacuum in accordance with the manufacturer's design.

(4) Each opening into the internal floating roof for a fixed roof support column may be equipped with a flexible fabric sleeve seal instead of a deck cover.

(5) Any external floating roof drain that empties into the stored liquid must be equipped with a slotted membrane fabric cover that covers at least 90% of the area of the opening or an equivalent control that must be kept in a closed (i.e., no gap of more than 1/8 inch) position at all times except when the drain is in actual use. Stub drains on an internal floating roof storage tank are not subject to this requirement.

(6) There must be no visible holes, tears, or other openings in any seal or seal fabric.

(7) For an external floating roof storage tank, secondary seals must be the rim-mounted type. The seal must be continuous from the floating roof to the tank wall, with the exception of gaps that do not exceed the following specification. The accumulated area of gaps that exceed 1/8 inch in width between the secondary seal and storage tank wall may not be greater than 1.0 square inch per foot of storage tank diameter.

(8) Each opening for a slotted guide pole in an external floating roof storage tank must be equipped with one of the following control device configurations:

(A) a pole wiper and pole float that has a seal or wiper at or above the height of the pole wiper:

(B) a pole wiper and a pole sleeve;

(C) an internal sleeve emission control system;

(D) a retrofit to a solid guide pole system;

(E) a flexible enclosure system; or

(F) a cover on an external floating roof tank.

(9) The external floating roof or internal floating roof must be floating on the liquid surface at all times, except as allowed under the following circumstances:

(A) during the initial fill or refill after the storage tank has been cleaned;

(B) when necessary for preventive maintenance, roof repair, primary seal inspection, or removal and installation of a secondary seal, if product is not transferred into or out of the storage tank, emissions are minimized, and the repair is completed within seven calendar days;

(C) when the storage tank has a storage capacity less than 25,000 gallons;

(D) when the vapors are routed to a control device from the time the storage tank has been emptied to the extent practical or the drain pump loses suction until the floating roof is within 10% by volume of being refloated;

(E) when all VOC emissions from the storage tank, including emissions from floating roof landings, have been included in an emissions limit or cap approved under Chapter 116 of this title (relating to Control of Air Pollution by Permits for New Construction or Modification) prior to March 1, 2013; or

(F) when all VOC emissions from floating roof landings at the regulated entity are less than 25 tons per year.

Source Note: The provisions of this §115.175 adopted to be effective July 21, 2021, 46 TexReg 4313