[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: 46CFR56.20-1]

[Page 182-183]
 
                           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. 56.20-1  General.


    (a) Valves certified in accordance with subpart 50.25 of this 
subchapter are acceptable for use in piping systems.
    (b) Non-welded valves complying with the standards listed in Sec. 
56.60-1 of this part may be used within the specified pressure and 
temperature ratings

[[Page 183]]

of those standards, provided the limitations of Sec. 56.07-10(c) of 
this part are applied. Materials must comply with subpart 56.60 of this 
part. Welded valves complying with the standards and specifications 
listed in Sec. 56.60-1 of this part may be used in Class II systems 
only unless they meet paragraph (c) of this section.
    (c) All other valves must meet the following:
    (1) All pressure-containing materials must be accepted in accordance 
with Sec. 56.60-1 of this part.
    (2) Valves must be designed so that the maximum allowable working 
pressure does not exceed one-fourth of the burst pressure or produce a 
primary stress greater than one-fourth of the ultimate tensile strength 
of the material for Class II systems and for all Class I, I-L, and II-L 
systems receiving ship motion dynamic analysis and nondestructive 
examination. For Class I, I-L, or II-L systems not receiving ship motion 
dynamic analysis and nondestructive examination under Sec. 56.07- 10(c) 
of this part, the maximum allowable working pressure must not exceed 
one-fifth of the burst pressure or produce a primary stress greater than 
one-fifth of the ultimate tensile strength of the material. The maximum 
allowable working pressure may be determined by--
    (i) Calculations comparable to those of ANSI B31.1 or Section VIII 
of the ASME Code, if the valve shape permits this;
    (ii) Subjecting a representative model to a proof test or 
experimental stress analysis described in paragraph A-22 of Section I of 
the ASME Code; or
    (iii) Other means specifically accepted by the Marine Safety Center.
    (3) Valves must be tested in accordance with Sec. 56.97-5 of this 
part.
    (4) If welded, valves must be welded in accordance with subpart 
56.70 of this part and part 57 of this chapter or by other processes 
specifically approved by the Marine Safety Center.
    (d) Where liquid trapped in any closed valve can be heated and an 
uncontrollable rise in pressure can result, means must be provided in 
the design, installation, and operation of the valve to ensure that the 
pressure in the valve does not exceed that allowed by this part for the 
attained temperature. (For example, if a flexible wedge gate valve with 
the stem installed horizontally is closed, liquid from testing, 
cleaning, or condensation can be trapped in the bonnet section of the 
closed valve.) Any resulting penetration of the pressure wall of the 
valve must meet the requirements of this part and those for threaded and 
welded auxiliary connections in ANSI B16.34.

[CGD 77-140, 54 FR 40604, Oct. 2, 1989; 55 FR 39968, Oct. 1, 1990]