Patent ID: 7481350

Claim:
A method of making a socket-welded metal joint with reduced residual stresses resulting from the welding, which method comprises I. providing an assembly comprising A. a hollow metal fitting which includes (1) an internal annular shoulder having an inner diameter and an outer diameter; and (2) an annular wall which (a) extends from the shoulder, (b) has a cylindrical inner surface, (c) has a cylindrical outer surface whose diameter is greater than the inner diameter of the shoulder, (d) defines with the shoulder a cylindrical socket having a common longitudinal axis with the annular wall, and (e) has an end surface connecting the cylindrical outer and inner surfaces, which end surface is chamfered so as to create a radially outward-facing chamfer whose profile is such that, as viewed in a cross section taken along the longitudinal axis, is concave, B. a metal pipe which includes at one end (1) a cylindrical outer surface which has a uniform radial profile and is free of any dam, pocket, projection, recess, or similar feature that could require the pipe to be configured, dimensioned, selected, or positioned to work with or otherwise correspond to a particular fitting, and (2) a cylindrical inner surface, with the endmost portion of the pipe at said end being disposed in the socket so that the outer surface of the pipe is within the inner surface of the annular wall of the socket; and II. welding the fitting and the pipe together by applying an annulus of added bead metal to the chamfered end surface of the fitting so as to surround the chamfered end surface, and fusing the base metal of the annular wall and pipe.