[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: 46CFR56.50-25]

[Page 196]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 56_PIPING SYSTEMS AND APPURTENANCES--Table of Contents
 
    Subpart 56.50_Design Requirements Pertaining to Specific Systems
 
Sec. 56.50-25  Safety and relief valve escape piping.

    (a) Escape piping from unfired steam generator, boiler, and 
superheater safety valves shall have an area of not less than that of 
the combined areas of the outlets of all valves discharging thereto and 
shall be led as near vertically as practicable to the atmosphere.
    (b) Expansion joints or flexible pipe connections shall be fitted in 
escape piping. The piping shall be adequately supported and installed so 
that no stress is transmitted to the safety valve body.
    (c) Safety or relief valve discharges, when permitted to terminate 
in the machinery space, shall be led below the floorplates or to a 
remote position to minimize the hazardous effect of the escaping steam.
    (d) The effect of the escape piping on the operation of the relief 
device shall be considered. The back pressure in the escape piping from 
the main propulsion steam generator should not exceed 10 percent of the 
relief device setting unless a compensated relief device is used. Back 
pressure must be calculated with all relief valves which discharge to a 
common escape pipe relieving simultaneously at full capacity.

[CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGD 77-140, 54 FR 
40608, Oct. 2, 1989; CGD 95-012, 60 FR 48050, Sept. 18, 1995]