California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 1 - Unfired Pressure Vessel Safety Orders › Article 7 - Compressed and Liquefied Natural Gas System › Section 533 - Location and Installation of Underground Tanks

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) General. Tanks and regulating equipment
					 shall not be buried below ground unless written permission to do so has been
					 obtained from the Division and the following special conditions are complied
					 with:
(1) The proposed location complies with
					 Order 531 (a) (1), (2) and (3).
(2)
					 The tank shall be set with the top at least 24 inches below the surface of the
					 ground, shall rest on firm foundations and shall not be installed under
					 roadways.
(3) Before any
					 back-filling is done, the installation shall be inspected by a qualified
					 inspector and shall comply with all applicable sections of these
					 Orders.
(4) The back-filling shall
					 be done in such a manner that there will be at least 6 inches of water-washed
					 sand free from soil, rocks or gravel immediately adjacent to the tank. The sand
					 shall be well tamped into place during the back-filling operation.
(5) All buried tanks shall be constructed for
					 underground service and the manufacturer shall provide means for lowering the
					 tank into place without damage to the tank or corrosion-resistant
					 coating.
(6) If the valves and
					 fittings are located in a curb box, adequate provision shall be provided for
					 proper drainage and ventilation of the curb box.
(7) No curb box shall be larger than
					 necessary for the operation and maintenance of the valves and fittings located
					 therein nor more than 3 feet in depth.
(8) All buried tanks shall be completely
					 uncovered for an inspection of all external surfaces at intervals of at least
					 once every 3 years.
The intervals may be changed at the discretion of the
						Division if a test plate is buried adjacent to the tank and shows no
						appreciable corrosion on inspection after 3 years of service; provided,
						however, that every tank shall be uncovered at least every 15 years. The test
						plates shall be of the same material as the shell of the tank and shall be at
						least ¼ of the tank diameter in length and 6 inches wide and shall be
						buried in water-washed sand at least as deep as the lowest surface of the tank,
						and shall not be coated. Test plates shall be provided in accordance with the
						following table:
(A) Tanks 10 feet or
					 less in length, one test plate.
(B)
					 Tanks more than 10 feet but less than 20 feet in length, 2 test plates, one on
					 each side near opposite ends.
(C)
					 Tanks 20 feet or more in length, one test plate for each 10 feet of length,
					 placed on alternate sides at 10-foot intervals.
(9) No tank used underground shall be
					 reinstalled aboveground until it has been inspected and found to be in
					 compliance with requirements for an aboveground installation.
(10) Where necessary, tanks shall be securely
					 anchored or weighted to prevent floating.