46 CFR §56.20-1

1. (a)Valves certified in accordance with subpart 50.25 of this subchapter are acceptable for use in piping systems.
2. (b)Non-welded valves complying with the standards listed in § 56.60-1 may be used within the specified pressure and temperature ratings of those standards, provided the limitations of § 56.07-10(c) are applied. Materials must comply with subpart 56.60. Welded valves complying with the standards and specifications listed in § 56.60-1 may be used in Class II systems only unless they meet paragraph (c) of this section.
3. (c)All other valves must meet the following:
   1. (1)All materials must be accepted in accordance with § 56.60-1.
   2. (2)The maximum allowable working pressure may be determined by § 56.15-1(c)(2).
   3. (3)Valves must be tested in accordance with the requirements of the applicable incorporated standard or subpart 56.97.
   4. (4)If welded, valves must be welded in accordance with subpart 56.70 and part 57 of this subchapter or by other processes specifically approved by the Marine Safety Center.