---
kind: "section"
citation: "46 C.F.R. § 56.30-5"
title: "46"
number: "56.30-5"
heading: "Welded joints."
url: "https://uscodex.org/cfr/46/56.30-5"
---

# §56.30-5. Welded joints.

- (a) **General.** Welded joints may be used for materials for which welding procedures, welders, and welding machine operators have been qualified in accordance with [part 57](/cfr/46/part57.md) of this subchapter.
- (b) **Butt welds—general.** Butt welds may be made with or without backing or insert rings within the limitations established in [§ 56.70-15](/cfr/46/56.70-15.md). When the use of backing rings will result in undesirable conditions such as severe stress concentrations, corrosion or erosion, then:
  - (1) The backing rings must be removed and the inside of the joint ground smooth, or
  - (2) The joint must be welded without backing rings, or
  - (3) Consumable insert rings must be used. Commonly used types of butt-welding end preparations are shown in ASME B16.25 (incorporated by reference; see [§ 56.01-2](/cfr/46/56.01-2.md)).
  - (4) Restrictions as to the use of backing rings appear for the low temperature piping systems and should be checked when designing for these systems.
- (c) **Socket welds.** (Modifies 127.3.3A.)
  - (1) Each socket weld must conform to ASME B16.11 (incorporated by reference; see [§ 56.01-2](/cfr/46/56.01-2.md)), to applicable standards listed in table 2 to [§ 56.60-1](/cfr/46/56.60-1.md), and to Figure 127.4.4C in ASME B31.1 (incorporated by reference; see [§ 56.01-2](/cfr/46/56.01-2.md)) as modified by [§ 56.30-10(b)(4)](/cfr/46/56.30-10.md?p=b-4).
  - (2) Restrictions on the use of socket welds appear in [§ 56.70-15(d)(3)](/cfr/46/56.70-15.md?p=d-3) for Class I service and in [§ 56.50-105](/cfr/46/56.50-105.md) for low temperature service. See [§ 56.70-15(d)(4)](/cfr/46/56.70-15.md?p=d-4) for Class II service.
- (d) **Fillet welds.** The size of a fillet weld is determined as shown in Figure 127.4.4A of ASME B31.1. Fillet-weld details for socket-welding components must meet [§ 56.30-5(c)](#c). Fillet-weld details for flanges must meet [§ 56.30-10](/cfr/46/56.30-10.md) (see also § [56.70-15(d)(3)](/cfr/46/56.70-15.md?p=d-3) and [(4)](/cfr/46/56.70-15.md?p=d-4) for applications of fillet welds).
- (e) **Seal welds.** Seal welds may be used but must not be considered as contributing any strength to the joint.

## Notes

### Amendments

[CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGFR 69-127, 35 FR 9978, June 17, 1970; CGD 77-140, 54 FR 40605, Oct. 2, 1989; CGD 95-012, 60 FR 48050, Sept. 18, 1995; USCG-2003-16630, 73 FR 65177, 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 CGFR 69-127, 35 FR 9978, June 17, 1970; CGD 77-140, 54 FR 40605, Oct. 2, 1989; CGD 95-012, 60 FR 48050, Sept. 18, 1995; USCG-2003-16630, 73 FR 65177, Oct. 31, 2008]