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 541 - Safety Relief Devices

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a)
					 General.
(1) Unless covered elsewhere in
					 these Orders, every natural gas tank shall be provided with one or more
					 spring-loaded safety relief valves set to open as follows with relation to the
					 maximum allowable working pressure:
Type of
								Vessel
Minimum Safety Relief Valve
								Setting
Maximum Safety Relief Valve
								Setting
ASME Code Constructed Vessels with a factor of
								safety of 5 or more..........................
100%
125%
ASME Code Constructed Vessels built with a factor
								of safety of less than
								5..........................
100%
110%
DOT Cylinders--Safety Relief
								Devices..........................
As approved by Bureau of
								  Explosives
All safety relief valves required by this Order shall be
						ASME labeled except for safety relief devices on DOT cylinders and safety
						relief valves as required in 537 (c)(3), which may be ASME or Underwriters'
						Laboratories rated and stamped.
(2) Each safety relief valve shall be plainly
					 marked by the manufacturer of the valve with the pressure in pounds per square
					 inch at which the valve is set to start to discharge and the discharge capacity
					 in cubic feet per minute (cfm) air.
(3) No shutoff valves shall be installed
					 between the safety relief valves and the tank without written permission from
					 the Division except that a shutoff valve may be used on multiple valve
					 installations where the arrangement of the valves will provide full required
					 flow through the safety relief valves at all times. The opening or connection
					 between the tank and safety relief valve or valves shall have at least the
					 combined areas of all connected safety relief valve inlets.
(4) Safety relief valves shall be so arranged
					 that they will have an unobstructed full size discharge to a safe place, and
					 shall be so arranged that escaping gas will not impinge on the vessel, valves
					 or fittings.
(5) Except for safety
					 valves that are integral with service valves, safety relief valves on tanks and
					 cylinders shall be installed in a vertical position and shall be fitted with
					 suitable raincaps.
(6) Safety
					 relief valves for natural gas service shall not be fitted with lifting devices.
					 The adjustment if external shall be provided with means for sealing the
					 adjustment to prevent tampering by unauthorized persons. If at any time it is
					 necessary to break such seal, the valve shall be removed from service until it
					 has been reset and sealed. Any adjustments necessary to natural gas safety
					 relief valves shall be made by the manufacturer or other companies having
					 competent personnel and adequate facilities for the repair, adjustment and
					 testing of such valves. The organization making such adjustment shall attach a
					 permanent tag with the setting, capacity and date. All safety relief devices
					 shall be tested at least annually and maintained in proper operating
					 condition.
(7) If pressure
					 regulators are used, a safety relief device shall be provided on the
					 low-pressure side of each final stage regulator and on the low-pressure side of
					 all other regulators unless the piping and/or fittings from the low-pressure
					 side of such regulators to the high-pressure side of the next stage regulation
					 are suitable for full tank pressure.
(8) Safety relief valves for surge tanks
					 containing vapor only shall have a relieving capacity of not less than the
					 maximum input from the system, vaporizer or reducing valves.
(9) Fusible plugs and/or rupture discs are
					 prohibited for primary relief devices except as permitted in (b) (3)
					 below.
(10) On underground
					 installations, the discharge from safety relief valves shall be vertically
					 upward and shall be piped to a point at least 10 feet aboveground, and shall
					 meet the requirements for the location of tanks as specified in Order 531 (a)
					 (1), (2) and (3).