---
kind: "section"
citation: "46 C.F.R. § 154.524"
title: "46"
number: "154.524"
heading: "Piping joints: Welded and screwed couplings."
url: "https://uscodex.org/cfr/46/154.524"
---

# §154.524. Piping joints: Welded and screwed couplings.


Pipe lengths without flanges must be joined by one of the following:

- (a) A butt welded joint with complete penetration at the weld root except that for design temperatures colder than −10 °C (14 °F) the butt weld must be double welded or must be welded using:
  - (1) A backing ring that for design pressures greater than 979 kPa gauge (142 psig) must be removed after the weld is completed;
  - (2) A consumable insert; or
  - (3) **An inert gas back-up on the first weld pass.**
- (b) A slip-on welded joint with sleeves and attachment welds is allowed for an open ended pipe with an external diameter of 50 mm (2 in.) or less and a design temperature of −55 °C (−67 °F), or warmer.
- (c) A socket weld fitting with attachment welds is allowed for pipe with an external diameter of 50 mm (2 in.) or less and a design temperature of −55 °C (−67 °F) or warmer.
- (d) Screwed couplings are allowed for instrumentation and control piping that meets [§ 56.30-20](/cfr/46/56.30-20.md) and § [56.50-105 (a)(4)](/cfr/46/56.50-105.md?p=a-4) and [(b)(4)](/cfr/46/56.50-105.md?p=b-4) of this chapter.
- (e) **A method or fitting specially approved by the Commandant (CG-ENG).**

## Notes

### Amendments

[CGD 74-289, 44 FR 26009, May 3, 1979, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983]

### Authority

Authority: 46 U.S.C. 3703, 9101; Department of Homeland Security Delegation No. 0170.1.

### Source

Source: CGD 74-289, 44 FR 26009, May 3, 1979, unless otherwise noted.

### Amendments

[CGD 74-289, 44 FR 26009, May 3, 1979, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983]