Pennsylvania Code & Bulletin

• No statutes or acts will be found at this website.

The Pennsylvania Code website reflects the Pennsylvania Code changes effective through 54 Pa.B. 1032 (February 24, 2024).

25 Pa. Code § 129.56. Storage tanks greater than 40,000 gallons capacity containing VOCs.

§ 129.56. Storage tanks greater than 40,000 gallons capacity containing VOCs.

 (a)  No person may permit the placing, storing or holding in a stationary tank, reservoir or other container with a capacity greater than 40,000 gallons of volatile organic compounds with a vapor pressure greater than 1.5 psia (10.5 kilopascals) under actual storage conditions unless the tank, reservoir or other container is a pressure tank capable of maintaining working pressures sufficient at all times to prevent vapor or gas loss to the atmosphere or is designed and equipped with one of the following vapor loss control devices:

   (1)  An external or an internal floating roof. This control equipment may not be permitted if the volatile organic compounds have a vapor pressure of 11 psia (76 kilopascals) or greater under actual storage conditions.

   (2)  Vapor recovery system. A vapor recovery system, consisting of a vapor gathering system capable of collecting the volatile organic compound vapors and gases discharged and a vapor disposal system capable of processing such volatile organic vapors and gases so as to prevent their emission to the atmosphere. Tank gauging and sampling devices shall be gas-tight except when gauging or sampling is taking place. The vapor recovery system shall be maintained in good working order and recover at least 80% of the vapors emitted by such tank.

 (b)  An external floating roof shall be fitted with a primary seal and a continuous secondary seal extending from the floating roof to the tank wall (rim-mounted secondary seal). The external floating roof shall meet the following equipment requirements:

   (1)  Seal closure devices shall meet the following requirements:

     (i)   There are no visible holes, tears or other openings in the seals or seal fabric.

     (ii)   The seals are intact and uniformly in place around the circumference of the floating roof between the floating roof and the tank wall.

     (iii)   For tanks with vapor-mounted primary seals, the accumulated area of gaps exceeding 1/8 inch in width between the secondary seal and the tank wall shall not exceed 1 square inch per foot of tank diameter. Compliance with this subsection shall be determined by physically measuring the length and width of gaps around the entire circumference of the secondary seal in each place where a 1/8 inch uniform diameter probe passes freely (without forcing or binding against the seal) between the seal and tank wall and by summing the area of the individual gaps.

   (2)  Openings in the external floating roof, except for automatic bleeder vents, rim space vents and leg sleeves, are as follows:

     (i)   Equipped with covers, seals or lids in the closed position except when the openings are in actual use.

     (ii)   Equipped with projections into the tank which remain below the liquid surface at all times.

   (3)  Automatic bleeder vents are closed at all times except when the roof is floated off or landed on the roof leg supports.

   (4)  Rim vents are set to open when the roof is being floated off the leg supports or at the recommended setting of the manufacturer.

   (5)  Emergency roof drains are provided with slotted membrane fabric covers or equivalent covers which cover at least 90% of the area of the opening.

 (c)  An internal floating roof shall be fitted with a primary seal and shall comply with the following equipment requirements:

   (1)  A closure seal or seals, to close the space between the roof edge and tank wall is used.

   (2)  There are no holes, tears or other openings in the seal or a seal fabric or materials.

   (3)  Openings except stub drains are equipped with covers, lids or seals such that:

     (i)   The cover, lid or seal is in the closed position at all times except when in actual use.

     (ii)   Automatic bleeder vents are closed at all times except when the roof is floated off or landed on the roof leg supports.

     (iii)   Rim vents, if provided are set to open when the roof is being floated off the roof leg supports or at the recommended setting of the manufacturer.

 (d)  This section does not apply to petroleum liquid storage vessels which:

   (1)  Are used to store waxy, heavy pour crude oil.

   (2)  Have capacities less than 420,000 gallons and are used to store produced crude oil and condensate prior to lease custody transfer.

 (e)  For the purposes of this section, the petroleum liquid storage vessels listed in this subsection comply with the equipment requirements of this section. These tanks shall comply with the maintenance, inspection and reporting requirements of this section. These petroleum liquid storage vessels are those:

   (1)  Which contain a petroleum liquid with a true vapor pressure less than 4 psia (27.6 kilopascals) and which are of welded construction and which presently possess a metallic-type shoe seal, a liquid-mounted foam seal, a liquid-mounted liquid filled type seal or other closure device of demonstrated equivalence approved by the Department.

   (2)  Which are of welded construction, equipped with a metallic-type shoe primary seal and has a secondary seal from the top of the shoe seal to the tank wall (shoe-mounted secondary seal).

 (f)  The owner or operator of a petroleum liquid storage vessel with a floating roof subject to this regulation shall:

   (1)  Perform routine inspections annually in order to insure compliance with subsection (b) or (c). The inspection shall include a visual inspection of the secondary seal gap when inspecting external floating roof tanks.

   (2)  For external floating roof tanks, measure the secondary seal gap annually in accordance with subsection (b)(1)(iii) when the floating roof is equipped with a vapor-mounted primary seal.

   (3)  Maintain records of the types of volatile petroleum liquids stored, the maximum true vapor pressure of the liquid as stored, and the results of the inspections performed in subsection (f)(1) and (2). Copies of the records shall be retained by the owner or operator for a period of 2 years after the date on which the record was made and shall be made available to the Department upon written or verbal request at a reasonable time.

 (g)  For volatile organic compounds whose storage temperature is governed by ambient weather conditions, the vapor pressure under actual storage conditions shall be determined using a temperature which is representative of the average storage temperature for the hottest month of the year in which the storage takes place.

 (h)  If a failure is detected during inspections required in this section, the owner or operator, or both, shall repair the items or empty and remove the storage vessel from service within 45 days. If this failure 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. A request for an extension shall document that alternate storage capacity is unavailable and specify a schedule of actions the owner or operator will take that will assure that the equipment will be repaired or the vessel will be emptied as soon as possible but within the additional 30-day time requested.


   The provisions of this §  129.56 issued under section 1920-A of The Administrative Code of 1929 (71 P.S. §  510-20); and section 5 of the Air Pollution Control Act (35 P.S. §  4005).


   The provisions of this §  129.56 adopted April 27, 1979, effective August 1, 1979, 9 Pa.B. 1447; corrected May 11, 1979, effective August 1, 1979, 9 Pa.B. 1534; amended September 26, 1980, effective September 27, 1980, 10 Pa.B. 3788; amended June 19, 1981, effective June 20, 1981, 11 Pa.B. 2118; amended August 12, 1983, effective August 13, 1983, 13 Pa.B. 2478; amended September 4, 1998, effective September 5, 1998, 28 Pa.B. 4525. Immediately preceding text appears at serial pages (199522) to (199524).

Cross References

   This section cited in 25 Pa. Code §  129.51 (relating to general); 25 Pa. Code §  129.54 (relating to seasonal operation of auxiliary incineration equipment); 25 Pa. Code §  129.57 (relating to storage tanks less than or equal to 40,000 gallons capacity containing VOCs); 25 Pa. Code §  129.60 (relating to bulk gasoline plants); 25 Pa. Code §  129.91 (relating to control of major sources of NOx and VOCs); 25 Pa. Code §  129.96 (relating to applicability); and 25 Pa. Code §  129.111 (relating to applicability).

No part of the information on this site may be reproduced for profit or sold for profit.

This material has been drawn directly from the official Pennsylvania Code full text database. Due to the limitations of HTML or differences in display capabilities of different browsers, this version may differ slightly from the official printed version.