[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: 46CFR56.50-40]

[Page 198]
 
                           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. 56.50-40  Blowoff piping (replaces 102.2.5(d)).

    (a)(1) The requirements for blowoff piping in this section shall be 
followed in lieu of the requirements in 102.2.5(d) in ANSI-B31.1.
    (2) Where blowoff valves are connected to a common discharge from 
two or more boilers, a nonreturn valve shall be provided in the line 
from each boiler to prevent accidental blowback in the event the boiler 
blowoff valve is left open.
    (b) Blowoff piping external to the boiler shall be designed for not 
less than 125 percent of the maximum allowable working pressure of the 
boiler, or the maximum allowable working pressure of the boiler plus 225 
pounds per square inch, whichever is less. When the required blowoff 
piping design pressure exceeds 100 pounds per square inch gage, the wall 
thickness of the piping shall not be less than Schedule 80. The value of 
allowable stress for design purposes shall be selected as described in 
Sec. 56.07-10(e) at a temperature not below that of saturated steam at 
the maximum allowable working pressure of the boiler.
    (c) Boiler blowoff piping which discharges above the lightest 
loadline of a vessel shall be arranged so that the discharge is 
deflected downward.
    (d) Valves such as the globe type so designed as to form pockets in 
which sediment may collect shall not be used for blowoff service.

[CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGFR 69-127, 35 
FR 9978, June 17, 1970; CGD 73-254, 40 FR 40165, Sept. 2, 1975]