NR 440.285(3)(a)1.i.i. Each penetration of the internal floating roof that allows for passage of a ladder shall have a gasketed sliding cover. NR 440.285(3)(a)2.2. An external floating roof. An external floating roof means a pontoon-type or double-deck type cover that rests on the liquid surface in a vessel with no fixed roof. Each external floating roof shall meet the following specifications: NR 440.285(3)(a)2.a.a. Each external floating roof shall be equipped with a closure device between the wall of the storage vessel and the roof edge. The closure device is to consist of 2 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. 1) The primary seal shall be either a mechanical shoe seal or a liquid-mounted seal. Except as provided in sub. (4) (b) 4., the seal shall completely cover the annular space between the edge of the floating roof and storage vessel wall.
2) The secondary seal shall completely cover the annular space between the external floating roof and the wall of the storage vessel in a continuous fashion except as allowed in sub. (4) (b) 4.
NR 440.285(3)(a)2.b.b. Except for automatic bleeder vents and rim space vents, each opening in a noncontact external floating roof shall provide a projection below the liquid surface. Except for automatic bleeder vents, rim space vents, roof drains, and leg sleeves, each opening in the roof is to be equipped with a gasketed cover, seal, or lid that is to be maintained in a closed position at all times (i.e., no visible gap) except when the device is in actual use. Automatic bleeder vents are to be closed at all times when the roof is floating except when the roof is being floated off or is being landed on the roof leg supports. Rim vents are to be set to open when the roof is being floated off the roof leg supports or at the manufacturer’s recommended setting. Automatic bleeder vents and rim space vents are to be gasketed. Each emergency roof drain is to be provided with a slotted membrane fabric cover that covers at least 90% of the area of the opening. NR 440.285(3)(a)2.c.c. The roof shall be floating on the liquid at all times (i.e., off the roof leg supports) except during initial fill until the roof is lifted off leg supports and when the storage vessel is completely emptied and subsequently refilled. The process of filling, emptying, or refilling when the roof is resting on the leg supports shall be continuous and shall be accomplished as rapidly as possible. NR 440.285(3)(a)3.3. A closed vent system and control device meeting the following specifications: NR 440.285(3)(a)3.a.a. The closed vent system shall be designed to collect all VOC vapors and gases discharged from the storage vessel and operated with no detectable emissions as indicated by an instrument reading of less than 500 ppm above background and visual inspections, as determined in s. NR 440.62 (6) (b). NR 440.285(3)(a)3.b.b. The control device shall be designed and operated to reduce inlet VOC emissions by 95% or greater. If a flare is used as the control device, it shall meet the specifications described in the general control device requirements under s. NR 440.18. NR 440.285(3)(b)(b) The owner or operator of each storage vessel with a design capacity greater than or equal to 75 m3 which contains a VOL that, as stored, has a maximum true vapor pressure greater than or equal to 76.6 kPa shall equip each storage vessel with one of the following: NR 440.285(4)(4) Testing and procedures. The owner or operator of each storage vessel as specified in sub. (3) (a) shall meet the requirements of par. (a), (b), or (c). The applicable paragraph for a particular storage vessel depends on the control equipment installed to meet the requirements of sub. (3). NR 440.285(4)(a)(a) After installing the control equipment required to meet sub. (3) (a) 1. (permanently affixed roof and internal floating roof), each owner or operator shall: NR 440.285(4)(a)1.1. Visually inspect the internal floating roof, the primary seal, and the secondary seal (if one is in service), prior to filling the storage vessel with VOL. If there are holes, tears or other openings in the primary seal, the secondary seal, or the seal fabric or defects in the internal floating roof, or both, the owner or operator shall repair the items before filling the storage vessel. NR 440.285(4)(a)2.2. For vessels equipped with a liquid-mounted or mechanical shoe primary seal, visually inspect the internal floating roof and the primary seal or the secondary seal (if one is in service) through manholes and roof hatches on the fixed roof at least once every 12 months after initial fill. If the internal floating roof is not resting on the surface of the VOL inside the storage vessel, or there is liquid accumulated on the roof, or the seal is detached, or there are holes or tears in the seal fabric, the owner or operator shall repair the items or empty and remove the storage vessel from service within 45 days. If a failure that is detected during inspections required under this paragraph cannot be repaired within 45 days and if the vessel cannot be emptied within 45 days, a 30-day extension may be requested from the department in the inspection report required in sub. (6) (a) 3. A request for an extension shall document that alternate storage capacity is unavailable and specify a schedule of actions the company owner or operator shall take to assure that the control equipment will be repaired or the vessel will be emptied as soon as possible. NR 440.285(4)(a)4.4. Visually inspect the internal floating roof, the primary seal, the secondary seal (if one is in service), gaskets, slotted membranes (if any), and sleeve seals (if any) each time the storage vessel is emptied and degassed. If the internal floating roof has defects, the primary seal has holes, tears or other openings in the seal or the seal fabric, the secondary seal has holes, tears or other openings in the seal or the seal fabric, the gaskets no longer close off the liquid surfaces from the atmosphere, or the slotted membrane has more than 10% open area, the owner or operator shall repair the items as necessary so that none of the conditions specified in this paragraph exist before refilling the storage vessel with VOL. In no event may inspections conducted in accordance with this provision occur at intervals greater than 10 years in the case of vessels undergoing annual visual inspections as specified in subds. 2. and 3. b. nor at intervals greater than 5 years in the case of vessels specified in subd. 3. a. NR 440.285(4)(a)5.5. Notify the department in writing at least 30 days prior to the filling or refilling of each storage vessel for which an inspection is required by subds. 1. and 4. to afford the department the opportunity to have an observer present. If the inspection required by subd. 4. is not planned and the owner or operator could not have known about the inspection 30 days in advance of refilling the storage vessel, the owner or operator shall notify the department at least 7 days prior to the refilling of the storage vessel. Notification shall be made by telephone immediately followed by written documentation demonstrating why the inspection was unplanned. Alternatively, this notification including the written documentation may be made in writing and sent by express mail so that it is received by the department at least 7 days prior to the refilling. NR 440.285(4)(b)(b) After installing the control equipment required to meet sub. (3) (a) 2. (external floating roof), the owner or operator shall: NR 440.285(4)(b)1.1. Determine the gap areas and maximum gap widths, between the primary seal and the wall of the storage vessel and between the secondary seal and the wall of the storage vessel according to the following frequency. NR 440.285(4)(b)1.a.a. Measurements of gaps between the storage vessel wall and the primary seal (seal gaps) shall be performed during the hydrostatic testing of the vessel or within 60 days of the initial fill with VOL and at least once every 5 years thereafter. NR 440.285(4)(b)1.b.b. Measurements of gaps between the storage vessel wall and the secondary seal shall be performed within 60 days of the initial fill with VOL and at least once per year thereafter. NR 440.285(4)(b)1.c.c. If any source ceases to store VOL for a period of one year or more, subsequent introduction of VOL into the vessel shall be considered an initial fill for the purposes of subd. 1. a. and b. NR 440.285(4)(b)2.2. Determine gap widths and areas in the primary and secondary seals individually by the following procedures: