Md. Code Regs. 26.11.13.03 - Large Storage Tanks

A. Closed Top Tanks.

(1) Equipment Requirements. A person may not place or store gasoline or VOC having a TVP between 1.5 psia (10.3 kilonewton/square meter) and 11 psia (75.6 kilonewton/square meter), inclusive, in any closed top tank with a capacity of 40,000 gallons (151,400 liters) or greater unless the:

(a) Tank's gauging and sampling devices are gas tight except when in use; and

(b) Tank is equipped with one of the following properly installed, operating, and well maintained emission control systems:

(i) An internal floating roof equipped with a primary and secondary seal;

(ii) A pressure tank system that maintains a pressure at all times to prevent loss of vapors to the atmosphere; or

(iii) A vapor control system capable of collecting the vapors from the tank and disposing of these vapors to prevent their emission to the atmosphere.

(2) Seal Requirements.

(a) There shall be no visible holes, tears, or other openings in a seal or seal fabric.

(b) Each seal shall be intact and uniformly in place around the circumference of the floating roof between the floating roof and the tank wall.

(c) The accumulated area of the gaps between the secondary seal and the tank wall and between the seal and other obstructions inside the tank (that is, ladder, roof supports) that are greater than 1/8 inch in width may not exceed 1.0 square inch per foot of tank diameter.

(d) The secondary seal requirement in §A(1)(b) of this regulation is waived until completion of an internal inspection as required in §A(3)(b) and (c)of this regulation. However, the secondary seal shall be installed not later than 5 years after the effective date of this regulation.

(3) Inspection Requirements. A person owning a gasoline or VOC storage tank subject to §A(1)(b)(i) of this regulation shall:

(a) Perform an annual visual inspection of the internal floating roof and seals from the roof hatch and record the findings;

(b) If the visual inspection shows noncompliance with the seal requirements in §A(2)(a) and (b) of this regulation, or liquid gasoline or VOC on the roof, perform an internal inspection of the floating roof and seals;

(c) After installing the secondary seal as required in §A(2)(d) of this regulation, conduct an internal inspection of each tank and its seals within 10 years from the date of the last internal inspection; and

(d) Notify the Department of an intended internal tank inspection at least 15 days before the proposed inspection date.

(4) Inspection Procedures. A person owning or operating a gasoline or VOC storage tank shall determine the total seal gap by summing the areas of the individual gaps. The lengths and widths of the gaps are measured by passing a 1/8 inch diameter probe between the seal and the tank wall and other obstructions in the tank. (The probe should move freely without forcing or binding against the seal.)

B. Open Top Tanks.

(1) Applicability.

(a) The use of open top tanks is prohibited for gasoline or VOC having a TVP exceeding 11 psia (75.6 kilonewton/square meter).

(b) Open top storage tanks at pipeline breakout stations are exempt from the secondary seal requirements in §B(2)(a) of this regulation.

(2) Equipment Requirements. A person may not place or store gasoline or VOC having a TVP of 1.5 psia (10.3 kilonewton/square meter) or greater in any open top tank with a capacity of 40,000 gallons (151,400 liters) or greater unless it is equipped with a properly installed and maintained external floating roof that meets all the following requirements:

(a) The external floating roof shall be equipped with a primary and secondary seal.

(b) Openings in the external floating roof, except for automatic bleeder vents, rim space vents, and leg sleeves, shall be equipped with a projection below the liquid surface. The opening with projections shall also be equipped with a cover, seal, or lid, which shall be maintained in a closed position at all times, except when the device is in actual use.

(c) Automatic bleeder vents shall be closed at all times except when the roof is resting on the roof supports. Rim vents shall be set to the open position when the roof is being floated off the leg supports or at the manufacturer's recommended setting.

(d) Roof drains shall be provided with a slotted membrane fabric or equivalent cover that encapsulates at least 90 percent of the area of the drain opening.

(3) Seal Requirements.

(a) There shall be no visible holes, tears, or other openings in a seal or seal fabric.

(b) Each seal shall be intact and uniformly in place around the circumference of the floating roof between the floating roof and the tank wall.

(c) The accumulated area of the gaps between the secondary seal and the tank wall that are greater than 1/8 inch in width may not exceed 1.0 square inch per foot of tank diameter.

(4) Inspection Requirements. A person who owns or operates an open top gasoline or VOC storage tank shall meet all of the following requirements:

(a) Perform semiannual routine visual inspections of the primary and secondary seals.

(b) Once a year, determine the total secondary seal gap by summing the areas of the individual gaps between the secondary seal and the tank wall over the entire circumference of the tank. The lengths and widths of the gaps are measured by passing a 1/8 inch uniform diameter probe between the seal and tank wall. (The probe shall move freely without forcing or binding against the seal.)

(c) Notify the Department of an intended tank inspection at least 15 days before the proposed inspection date.

(5) Requirements for Pipeline Breakout Stations. A person may not transfer gasoline through an open top gasoline storage tank at a pipeline breakout station unless the vapor space between the floating roof and the tank bottom is reduced to less than or equal to 20 inches (0.457 meter) in height.

C. Record Keeping for Large Storage Tanks. The owner or operator shall:

(1) Record the results of all inspections of floating roofs and seals;

(2) Record all repairs or replacement of the seals, and include in the record the date and the action taken;

(3) For each tank, record the average monthly storage temperature and throughput; and

(4) Maintain all records for at least 2 years, and make these records available to the Department upon request.

Notes

Md. Code Regs. 26.11.13.03

Regulations .03 amended, .02C adopted, and .05F repealed effective August 16, 1983 (10:14 Md. R. 1262)
Regulations .03 adopted effective May 8, 1991 (18:6 Md. R. 688)