§54.15-25. Minimum relief capacities for cargo tanks containing compressed or liquefied gas.
46 C.F.R. § 54.15-25
Each tank must be fitted with one or more safety relief valves designed, constructed, and flow tested in accordance with subpart 162.017 or 162.018 in subchapter Q of this chapter. Valves conforming to specification subpart 162.017 must be limited to use on tanks whose maximum allowable working pressure is not in excess of 10 pounds per square inch. With specific approval of the Commandant, such valves may be connected to the vessel in lieu of being directly fitted to the tanks.
The discharge pressure and the maximum overpressure permitted must be in accordance with § 54.15-5.
The rate of discharge for heat input of fire must meet the following formula:
For an independent tank that has a portion of the tank protruding above the open deck, the fire exposure factor must be calculated for the surface area above the deck and the surface area below the deck, and this calculation must be specially approved by the U.S. Coast Guard, Office of Design and Engineering Standards (CG-ENG).
In determining the total safety valve relieving capacity, the arrangement and location of the valves on the tank will be evaluated. The valves must be placed so that a number of valves sufficient to provide the required relieving capacity must always be in communication with the cargo vapor phase. The possible motions which the tank may see in its intended service and attendant changes in cargo liquid level will be considered. Shut off valves must not be installed between the vessel and the safety relief valves. Manifolds for mounting multiple relief valves may be fitted with acceptable interlocking shut off valves so arranged that the required capacity of discharge will be “lined up” at all times.
Each safety relief valve must be tested in the presence of a marine inspector before being placed in service except as noted otherwise in paragraph (e)(2) of this section. The test must satisfactorily show that the valve will start to discharge at the required minimum pressure.
Each safety relief valve fitted with a breaking pin and rupture disk need not be tested in the presence of a marine inspector before being placed in service. In lieu thereof, a certificate must be furnished with the valve attested to by the manufacturer that the test requirements of paragraph (e)(1) of this section have been met.
Notes, amendments, and revision history
Amendments
[CGFR 68-82, 33 FR 18828, Dec. 18, 1968, as amended by CGD 74-289, 44 FR 26007, May 3, 1979; CGD 82-063b, 48 FR 4781, Feb. 3, 1983; CGD 95-072, 60 FR 50462, Sept. 29, 1995; CGD 96-041, 61 FR 50728, Sept. 27, 1996; USCG-2004-18884, 69 FR 58346, Sept. 30, 2004; USCG-2007-29018, 72 FR 53965, Sept. 21, 2007; USCG-2009-0702, 74 FR 49228, Sept. 25, 2009; USCG-2012-0832, 77 FR 59777, Oct. 1, 2012]
Authority
Authority: 33 U.S.C. 1509; 43 U.S.C. 1333; 46 U.S.C. 3306, 3703; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; Department of Homeland Security Delegation No. 00170.1, Revision No. 01.3.
Source
Source: CGFR 68-82, 33 FR 18828, Dec. 18, 1968, as amended by USCG-2020-0634, 89 FR 50104, June 12, 2024, unless otherwise noted.
Amendments
[CGFR 68-82, 33 FR 18828, Dec. 18, 1968, as amended by CGD 74-289, 44 FR 26007, May 3, 1979; CGD 82-063b, 48 FR 4781, Feb. 3, 1983; CGD 95-072, 60 FR 50462, Sept. 29, 1995; CGD 96-041, 61 FR 50728, Sept. 27, 1996; USCG-2004-18884, 69 FR 58346, Sept. 30, 2004; USCG-2007-29018, 72 FR 53965, Sept. 21, 2007; USCG-2009-0702, 74 FR 49228, Sept. 25, 2009; USCG-2012-0832, 77 FR 59777, Oct. 1, 2012]