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TITLE 30ENVIRONMENTAL QUALITY
PART 1TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
CHAPTER 115CONTROL OF AIR POLLUTION FROM VOLATILE ORGANIC COMPOUNDS
SUBCHAPTER BGENERAL VOLATILE ORGANIC COMPOUND SOURCES
DIVISION 1STORAGE OF VOLATILE ORGANIC COMPOUNDS
RULE §115.112Control Requirements

    (D) 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.

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

    (F) 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.

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

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

      (ii) a pole wiper and a pole sleeve;

      (iii) an internal sleeve emission control system;

      (iv) a retrofit to a solid guidepole system;

      (v) a flexible enclosure system; or

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

    (H) The external floating roof or internal floating roof must be floating on the liquid surface at all times except as specified in this subparagraph. The external floating roof or internal floating roof may be supported by the leg supports or other support devices, such as hangers from the fixed roof, during the initial fill or refill after the storage tank has been cleaned or as allowed under the following circumstances:

      (i) when necessary for maintenance or inspection;

      (ii) when necessary for supporting a change in service to an incompatible liquid;

      (iii) when the storage tank has a storage capacity less than 25,000 gallons or the vapor pressure of the material stored is less than 1.5 psia;

      (iv) when the vapors are routed to a control device from the time the floating roof is landed until the floating roof is within ten percent by volume of being refloated;

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

      (vi) when all VOC emissions from floating roof landings at the regulated entity, as defined in §101.1 of this title (relating to Definitions), are less than 25 tons per year.

  (3) Vapor control systems, as defined in §115.10 of this title, used as a control device on any storage tank must maintain a minimum control efficiency of 90%.

  (4) For a storage tank storing condensate, as defined in §101.1 of this title, prior to custody transfer, flashed gases must be routed to a vapor control system if the liquid throughput through an individual tank or the aggregate of tanks in a tank battery exceeds 1,500 barrels (63,000 gallons) per year.

  (5) For a storage tank storing crude oil or condensate prior to custody transfer or at a pipeline breakout station, flashed gases must be routed to a vapor control system if the uncontrolled VOC emissions from an individual storage tank, or from the aggregate of storage tanks in a tank battery, equal or exceed 25 tons per year on a rolling 12-month basis. Uncontrolled emissions must be estimated by one of the following methods; however, if emissions determined using direct measurements or other methods approved by the executive director under subparagraph (A) or (D) of this paragraph are higher than emissions estimated using the default factors or charts in subparagraph (B) or (C) 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 §115.117 of this title (relating to Approved Test Methods).

    (B) 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.

    (C) For crude oil storage only, the owner or operator may use the chart in Exhibit 2 of the United States Environmental Protection Agency publication 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.

    (D) Other test methods or computer simulations may be allowed if approved by the executive director.

(e) The control requirements in this subsection apply in the Bexar County, Houston-Galveston-Brazoria, and Dallas-Fort Worth areas, except as specified in §115.119 of this title (relating to Compliance Schedules) and in paragraph (3) of this subsection. Beginning on the applicable compliance date specified in §115.183 of this title (relating to Compliance Schedules), the requirements in this subsection no longer apply to storage tanks storing crude oil or condensate that are subject to Division 7 of this subchapter (relating to Oil and Natural Gas Service in Ozone Nonattainment Areas).

  (1) No person shall place, store, or hold VOC in any storage tank unless the storage 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 control requirements specified in Table 1 of this paragraph for VOC other than crude oil and condensate or Table 2 of this paragraph for crude oil and condensate.

Attached Graphic

  (2) For an external floating roof or internal floating roof storage tank subject to the provisions of paragraph (1) of this subsection, the following requirements apply.

    (A) 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.

    (B) 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.

    (C) 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.

    (D) 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.

    (E) 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.

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

    (G) 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.

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

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

      (ii) a pole wiper and a pole sleeve;

      (iii) an internal sleeve emission control system;

      (iv) a retrofit to a solid guidepole system;

      (v) a flexible enclosure system; or

Cont'd...

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