[Code of Federal Regulations]
[Title 46, Volume 2]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR54.15-5]

[Page 156-157]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 54_PRESSURE VESSELS--Table of Contents
 
                  Subpart 54.15_Pressure-Relief Devices
 
Sec. 54.15-5  Protective devices (modifies UG-125).

    (a) All pressure vessels must be provided with protective devices. 
The protective devices must be in accordance with the requirements of 
UG-125

[[Page 157]]

through UG-136 of the ASME Code except as modified in this subpart.
    (b) An unfired steam boiler evaporator or heat exchanger (see Sec. 
54.01-10) shall be equipped with protective devices as required by Sec. 
54.15-15.
    (c) All pressure vessels other than unfired steam boilers shall be 
protected by pressure-relieving devices that will prevent the pressure 
from rising more than 10 percent above the maximum allowable working 
pressure, except when the excess pressure is caused by exposure to fire 
or other unexpected source of heat.
    (d) Where an additional hazard can be created by exposure of a 
pressure vessel to fire or other unexpected sources of external heat 
(for example, vessels used to store liquefied flammable gases), 
supplemental pressure-relieving devices shall be installed to protect 
against excessive pressure. Such supplemental pressure-relieving devices 
shall be capable of preventing the pressure from rising more than 20 
percent above the maximum allowable working pressure of the vessel. The 
minimum required relief capacities for compressed gas pressure vessels 
are given under Sec. 54.15-25. A single pressure-relieving device may 
be used to satisfy the requirements of this paragraph and paragraph (c) 
of this section, provided it meets the requirements of both paragraphs.
    (e) Pressure-relieving devices should be selected on the basis of 
their intended service. They shall be constructed, located, and 
installed so that they are readily accessible for inspection and repair 
and so arranged that they cannot be readily rendered inoperative.
    (f) Where pressure-indicating gages are used, they shall be chosen 
to be compatible with the pressure to be indicated. The size of the 
visual display, the fineness of graduations, and the orientation of the 
display will be considered. In no case shall the upper range of the gage 
be less than 1.2 times nor more than 2 times the pressure at which the 
relieving device is set to function.
    (g) The Commandant may authorize or require the use of a rupture 
disk in lieu of a relief or safety valve under certain conditions of 
pressure vessel use and design. See Sec. 54.15-13.
    (h) Vessels that are to operate completely filled with liquid shall 
be equipped with liquid relief valves unless otherwise protected against 
overpressure.
    (i) The protective devices required under paragraph (a) of this 
section shall be installed directly on a pressure vessel except when the 
source of pressure is external to the vessel, and is under such positive 
control that the pressure in the vessel cannot exceed the maximum 
allowable working pressure at the operating temperature except as 
permitted in paragraphs (c) and (d) of this section.
    (j) Pressure-relieving devices shall be constructed of materials 
suitable for the pressure, temperature, and other conditions of the 
service intended.
    (k) The opening through all pipes and fittings between a pressure 
vessel and its pressure-relieving device shall have at least the area of 
the pressure-relieving device inlet, and in all cases shall have 
sufficient area so as not to unduly restrict the flow to the pressure-
relieving device. The opening in the vessel shall be designed to provide 
direct and unobstructed flow between the vessel and its pressure-
relieving device.
    (l) Safety devices need not be provided by the pressure vessel 
manufacturer. However, overpressure protection shall be provided prior 
to placing the vessel in service.

[CGFR 68-82, 33 FR 18828, Dec. 18, 1968, as amended by CGD 88-032, 56 FR 
35822, July 29, 1991; CGD 95-012, 60 FR 48049, Sept. 18, 1995]