---
kind: "section"
citation: "46 C.F.R. § 162.018-4"
title: "46"
number: "162.018-4"
heading: "Construction and workmanship."
url: "https://uscodex.org/cfr/46/162.018-4"
---

# §162.018-4. Construction and workmanship.

- (a) Safety relief valves shall be of either the internal or external spring-loaded type, suitable for the intended service.
- (b) Safety relief valve body, base, bonnet and internals shall be designed for a pressure of not less than the set-pressure of the valve.
- (c) All safety relief valves shall be so constructed that the failure of any part cannot obstruct the free and full discharge of vapors from the valve.
- (d) The nominal size of a safety relief valve shall be the inside diameter of the inlet opening to the individual valve disk. No safety relief valve shall be smaller than 3/4 inch nor larger than 6 inches. Safety relief valves shall have flanged or welded end inlet connections and either flanged or screwed outlet connections, except outlets exceeding 4 inches in diameter shall be flanged.
- (e) Safety relief valves shall be of the angle or straight-through type, fitted with side or top outlet discharge connections.
- (f)
  - (1) Springs shall not show a permanent set exceeding 1 percent of their free length 10 minutes after being released from a cold compression test closing the spring solid.
  - (2) Springs may not be re-set for any pressure more than 10 percent above or 10 percent below that for which the valve is marked.
  - (3) If the operating conditions of a valve are changed so as to require a new spring under [paragraph (f)(2)](#f-2) of this section for a different pressure, the valve shall be adjusted by the manufacturer or his authorized representative.
- (g) The design and construction of safety relief valves shall permit easy access for inspection and repair.
- (h) Safety relief valves shall be tapped for not less than 1/4 inch pipe size drain at the lowest practicable point where liquid can collect.

## Notes

### Amendments

[CGFR 52-43, 17 FR 9540, Oct. 18, 1952]

### Authority

Authority: 33 U.S.C. 1321(j), 1903; 46 U.S.C. 3306, 3703, 4104, 4302; E.O. 12234, 45 FR 58801, 3 CFR, 1980 Comp., p. 277; E.O. 12777, 56 FR 54757, 3 CFR, 1991 Comp., p. 351; DHS Delegation 00170.1, Revision No. 01.4.

### Amendments

[CGFR 52-43, 17 FR 9540, Oct. 18, 1952]