Section 3440. Control technology guidelines

A. Filling of storage tanks. The tank should be a pressure tank maintaining working pressure sufficient at all times to prevent vapor loss to the atmosphere, or be designed and equipped with one of the following vapor control systems:

1. Filling of the tank through the use of a submerged fill pipe.

2. Any system of equal or greater control efficiency to the system in subsection A 1 of this section, provided such system is approved by the board.

B. Volatile organic compound storage - fixed roof tanks.

1. The tank should be a pressure tank maintaining working pressure sufficient at all times to prevent vapor loss to the atmosphere, or be designed and equipped with one of the following vapor control systems:

a. An internal floating roof resting on the surface of the liquid contents and equipped with a closure seal, or seals, to close the space between the roof edge and tank shell. All tank gauging and sampling devices should be vapor tight except when gauging or sampling is taking place.

b. Any system of equal or greater control efficiency to the system in subsection B 1 a of this section, provided such system is approved by the board.

2. There should be no visible holes, tears or other openings in the seal or any seal fabric.

3. All openings, except stub drains, should be equipped with a cover, seal or lid. The cover, seal or lid should be in a closed position at all times except when the device is in actual use. Automatic bleeder vents should be closed at all times except when the roof is floated off or landed on the roof leg supports. Rim vents, if provided should be set to open when the roof is being floated off the roof leg supports or at the manufacturer's recommended setting.

4. The exterior aboveground surfaces (exposed to sunlight) should be painted white, light pastels or light metallic and such exterior paint should be periodically maintained in good condition. Repainting may be performed during normal maintenance periods.

C. Volatile organic compound storage - floating roof tanks.

1. The tank should be designed and equipped with one of the following vapor control systems:

a. An external floating roof resting on the surface of the liquid contents and equipped with a seal closure device (meeting the specifications set forth in subsection C 2 and 3 of this section) to close the space between the roof edge and tank shell. All tank gauging and sampling devices should be vapor tight except when gauging or sampling is taking place.

b. Any system of equal or greater control efficiency to the system in subsection C 1 a of the section, provided such system is approved by the board.

2. Unless the tank is a welded tank fitted with a metallic-type shoe seal which has a secondary seal from the top of the shoe seal to the tank wall (a shoe-mounted secondary), the tank should be fitted with a continuous secondary seal extending from the floating roof to the tank wall (a rim-mounted secondary) if:

a. The tank is a welded tank, the true vapor pressure of the contained liquid is 4.0 psi or greater, and the primary seal is one of the following:

(1) A metallic-type shoe seal.

(2) A liquid-mounted foam seal.

(3) A liquid-mounted liquid-filled type seal.

(4) Any other seal closure device which can be demonstrated equivalent to the primary seals specified in subsection C 2 a (1) through (3) of this section.

b. The tank is a riveted tank, the true vapor pressure of the contained liquid is 1.5 psi, or greater, and the seal closure device is as described in subsection C 2 a of this section.

c. The tank is a welded or riveted tank, the true vapor pressure of the contained liquid is 1.5 psi, or greater, and the primary seal is vapor mounted. When such primary seal closure device can be demonstrated equivalent to the primary seals described in subsection C 2 a of this section the provisions of that subsection apply.

3. The seal closure devices should meet the following requirements:

a. There should be no visible holes, tears or other openings in the seal or any seal fabric.

b. The seal should be intact and uniformly in place around the circumference of the floating roof between the floating roof and the tank wall.

c. The areas where the gap between the secondary seal, installed pursuant to subsection C 2 c of this section, and the tank wall exceeds 1/8 inch in width shall be calculated in square inches. The sum of all such areas shall not exceed 1.0 square inch per foot of tank diameter.

4. All openings, except for automatic bleeder vents, rim space vents and leg sleeves, should provide a projection below the liquid surface. All openings, except stub drains, should be equipped with a cover, seal or lid. The cover, seal or lid should be in a closed position at all times except when the device is in actual use. Automatic bleeder vents should be closed at all times except when the roof is floated off or landed on the roof leg supports. Rim vents, if provided, should be set to open when the roof is being floated off the roof leg supports or at the manufacturer's recommended setting. Any emergency roof drain should be provided with a slotted membrane fabric cover or equivalent cover that covers at least 90% of the area of the opening.

5. The exterior above ground surfaces (exposed to sunlight) should be painted white, light pastels, or light metallic and such exterior paint should be periodically maintained in good condition. Repainting may be performed during normal maintenance periods.

Historical Notes

Derived from VR120-04-2504, eff. July 1, 1991.

Statutory Authority

§§ 10.1-1307 and 10.1-1308 of the Code of Virginia.