[Code of Federal Regulations]
[Title 46, Volume 2]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR56.30-5]

[Page 186-187]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 56_PIPING SYSTEMS AND APPURTENANCES--Table of Contents
 
        Subpart 56.30_Selection and Limitations of Piping Joints
 
Sec. 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 of this subchapter.
    (b) Butt welds--general. Butt welds may be made with or without 
backing or insert rings within the limitations established in Sec. 
56.70-15. When the use of backing rings will result in undesirable 
conditions such as severe stress concentrations, corrosion or erosion, 
then:
    (1) The backing rings shall be removed and the inside of the joint 
ground smooth, or
    (2) The joint shall be welded without backing rings, or
    (3) Consumable insert rings must be used. Commonly used types of 
butt welding end preparations are shown in ANSI B16.25.
    (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) Socket welds must conform 
to ANSI B16.11, applicable standards listed in Table 56.60-1(b) of this 
part, and Figure 127.4.4C in ANSI B31.1 as modified by Sec. 56.30-
10(b)(4) of this part. A gap of approximately one-sixteenth inch between 
the end of the pipe and the bottom of the socket must be provided before 
welding. This may best be provided by bottoming the pipe and backing off 
slightly before tacking.
    (2) Socket welds must not be used where severe erosion or crevice 
corrosion is expected to occur. Restrictions on the use of socket welds 
appear in

[[Page 187]]

Sec. 56.70-15(d)(3) of this part for Class I service and in Sec. 
56.50-105 of this part for low temperature service. These sections 
should be checked when designing for these systems. See Sec. 56.70-
15(d)(4) of this part for Class II service.
    (3) (Reproduces 111.3.4.) Drains and bypasses may be attached to a 
valve of fitting by socket welding provided the socket depth, bore 
diameter, and shoulder thickness conform to ANSI B16.11.
    (d) Fillet welds. Fillet welds may vary from convex to concave. The 
size of a fillet weld is determined as shown in Figure 127.4.4A of ANSI 
B31.1. Fillet weld details for socket-welding components must meet Sec. 
56.30-5(c) of this part. Fillet weld details for flanges must meet Sec. 
56.30-10 of this part. See also Sec. 56.70-15(d)(3) and (d)(4) of this 
part for applications of fillet welds.
    (e) Seal welds. Seal welds may be used but shall not be considered 
as contributing any strength to the joint.

[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]