[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: 46CFR56.20-15]

[Page 184-185]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 56_PIPING SYSTEMS AND APPURTENANCES--Table of Contents
 
                          Subpart 56.20_Valves
 
Sec. 56.20-15  Valves employing resilient material.

    (a) A valve in which the closure is accomplished by resilient 
nonmetallic material instead of a metal to metal seat shall comply with 
the design, material, construction and testing for valves specified in 
this part.
    (b) Valves employing resilient material shall be divided into three 
categories, Positive shutoff, Category A, and Category B, and shall be 
tested and used as follows:
    (1) Positive shutoff valves. The closed valve must pass less than 10 
ml/hr (0.34 fluid oz/hr) of liquid or less than 3 l/hr (0.11 cubic ft/
hr) of gas per inch nominal pipe size through the line after removal of 
all resilient material and testing at full rated pressure. Packing 
material must be fire resistant. Piping subject to internal head 
pressure from a tank containing oil must be fitted with positive shutoff 
valves located at the tank in accordance with Sec. 56.50-60(d). 
Otherwise positive shutoff valves may be used in any location in lieu of 
a required Category A or Category B valve.
    (2) Category A valves. The closed valve must pass less than the 
greater of 5 percent of its fully open flow rate or 15 percent divided 
by the square root of the nominal pipe size (NPS) of its fully open flow 
rate through the line after complete removal of all resilient seating 
material and testing at full rated pressure; as represented by the 
formula: (15% / SQRT x (NPS)) (Fully open flow rate). Category A valves 
may be used in any location except where positive shutoff valves are 
required by Sec. 56.50-60(d). Category A valves are required in the 
following locations:
    (i) Valves at vital piping system manifolds;
    (ii) Isolation valves in cross-connects between two piping systems, 
at least one of which is a vital system, where

[[Page 185]]

failure of the valve in a fire would prevent the vital system(s) from 
functioning as designed.
    (iii) Valves providing closure for any opening in the shell of the 
vessel.
    (3) Category B valves. The closed valve will not provide effective 
closure of the line or will permit appreciable leakage from the valve 
after the resilient material is damaged or destroyed. Category B valves 
are not required to be tested and may be used in any location except 
where a Category A or positive shutoff valve is required.
    (c) If a valve designer elects to use either calculations or actual 
fire testing in lieu of material removal and pressure testing, the 
proposed calculation method or test plan must be accepted by the 
Commandant (G-MSE).

[CGD 95-028, 62 FR 51200, Sept. 30, 1997]