---
kind: "section"
citation: "46 C.F.R. § 56.25-20"
title: "46"
number: "56.25-20"
heading: "Bolting."
url: "https://uscodex.org/cfr/46/56.25-20"
---

# §56.25-20. Bolting.

- (a)
  - (1) Bolts, studs, nuts, and washers must comply with applicable standards and specifications listed in [§ 56.60-1](/cfr/46/56.60-1.md). Bolting must be in accordance with ASME B16.5 (incorporated by reference; see [§ 56.01-2](/cfr/46/56.01-2.md)).
  - (2) Bolts and studs must extend completely through the nuts.
  - (3) See [§ 58.30-15(c)](/cfr/46/58.30-15.md?p=c) of this subchapter for exceptions on bolting used in fluid power and control systems.
- (b) Carbon steel bolts or bolt studs may be used if operating pressure does not exceed 300 psig and the operating temperature does not exceed 400 °F. Carbon steel bolts must have heavy hexagon heads in accordance with ASME B18.2.1 (incorporated by reference, see [§ 56.01-2](/cfr/46/56.01-2.md)) and must have heavy semifinished hexagonal nuts in accordance with ASME B18.2.2 (incorporated by reference, see [§ 56.01-2](/cfr/46/56.01-2.md)).
- (c) Alloy steel stud bolts must be threaded full length and use heavy semifinished hexagonal nuts in accordance with ASME B18.2.2.
- (d) Alloy bolts or studs and nuts are to be threaded in accordance with ASME B1.1 (incorporated by reference; see [§ 56.01-2](/cfr/46/56.01-2.md)), Class 2A external threads, and Class 2B internal threads (8-thread series 8UN for one inch and larger).
- (e) (Reproduces 108.5.1.) Washers, when used under nuts, must be of forged or rolled material with steel washers being used under steel nuts and bronze washers under bronze nuts.

## Notes

### Amendments

[CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGD 77-140, 54 FR 40605, Oct. 2, 1989; USCG-2000-7790, 65 FR 58460, Sept. 29, 2000; USCG-2003-16630, 73 FR 65176, Oct. 31, 2008]

### Source

Source: CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by USCG-2020-0634, 89 FR 50131, June 12, 2024, unless otherwise noted.

### Authority

Authority: 33 U.S.C. 1321(j), 1509; 43 U.S.C. 1333; 46 U.S.C. 3306, 3703; 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 No. 00170.1, Revision No. 01.4.

### Source

Source: CGFR 68-82, 33 FR 18843, Dec. 18, 1968, unless otherwise noted.

### Amendments

[CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGD 77-140, 54 FR 40605, Oct. 2, 1989; USCG-2000-7790, 65 FR 58460, Sept. 29, 2000; USCG-2003-16630, 73 FR 65176, Oct. 31, 2008]