[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: 46CFR54.15-13]

[Page 158]
 
                           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. 54.15-13  Rupture disks (modifies UG-127).

    (a) Paragraph UG-127 of the ASME Code provides for the use of 
rupture disks in series with spring loaded safety or relief valves.
    (b) For certain pressure vessels containing substances which may 
render a relief or safety valve inoperative, or where the installation 
of a valve is considered impractical, the Commandant may authorize or 
require the use of a rupture disk in parallel with or in lieu of a 
spring loaded safety or relief valve. These rupture disks shall:
    (1) Comply with the general provisions of Sec. 54.15-5 except as 
noted otherwise in this section;
    (2) Have a capacity for discharge such that the volume of release is 
sufficient to prevent the internal pressure from exceeding 120 percent 
of the ``maximum allowable working pressure'' with the pressure vessel 
exposed to fire conditions (see Sec. 54.15-25); and,
    (3) Operate at a pressure level which does not produce fatigue 
failure of the disk. The normal maximum operating pressure multiplied by 
1.3 shall not exceed the nominal disk burst pressure. (Notice that this 
restriction for protection of the rupture disk will usually require 
operation below the ``maximum allowable working pressure'' of the 
pressure vessel and therefore should be considered in design.)
    (c) All disks shall be oriented so that if rupture occurs, the disk 
fragments and pressure vessel discharge will be directed away from 
operating personnel and vital machinery.

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