§ 65.44 External floating roof (EFR).
(a) EFR design requirements. The owner or operator who elects to control storage vessel regulated material emissions by using an external floating roof shall comply with the design requirements listed in paragraphs (a)(1) through (3) of this section.
(1) The external floating roof shall be designed to float on the stored liquid surface except when the floating roof must be supported by the leg supports.
(2) The external floating roof shall be equipped with a closure device between the wall of the storage vessel and the roof edge.
(i) Except as provided in paragraph (a)(2)(iii) of this section, the closure device is to consist of two continuous seals, one above the other. The lower seal is referred to as the primary seal and the upper seal is referred to as the secondary seal.
(ii) Except as provided in paragraph (a)(2)(iv) of this section, the primary seal shall be either a metallic shoe seal or a liquid-mounted seal.
(iii) If the external floating roof is equipped with a liquid-mounted or metallic shoe primary seal as of December 31, 1992, the requirement for a secondary seal in paragraph (a)(2)(i) of this section does not apply until the next time the storage vessel is emptied and degassed, or by April 22, 2004, whichever occurs first.
(iv) If the external floating roof is equipped with a vapor-mounted primary seal and a secondary seal as of December 31, 1992, the requirement for a liquid-mounted or metallic shoe primary seal in paragraph (a)(2)(ii) of this section does not apply until the next time the storage vessel is emptied and degassed, or by April 22, 2004, whichever occurs first.
(3) The external floating roof shall meet the following specifications:
(i) Except for automatic bleeder vents (vacuum breaker vents) and rim space vents, each opening in the noncontact external floating roof shall provide a projection below the stored liquid surface except as provided in paragraph (a)(3)(xiii) of this section.
(ii) Covers on each access hatch and each gauge float well shall be designed to be bolted or fastened when they are closed.
(iii) Except for automatic bleeder vents, rim space vents, roof drains, and leg sleeves, each opening shall be equipped with a gasketed cover, seal, or lid.
(iv) Automatic bleeder vents and rim space vents shall be equipped with a gasket.
(v) Each roof drain that empties into the stored liquid shall be equipped with a slotted membrane fabric cover that covers at least 90 percent of the area of the opening.
(vi) Each unslotted and slotted guide pole well shall be equipped with a gasketed sliding cover or a flexible fabric sleeve seal.
(vii) Except for antirotational devices equipped with a welded cap, each unslotted guide pole shall be equipped with a gasketed cap on the end of the pole.