Patent ID: 8459527

Claim:
A welding jig capable of ensuring concentricity of an interior surface of a cylindrical pipe with (i) a circular outer periphery of a bolting flange; or (ii) a circular bolt hole pattern in said bolting flange; said welding jig comprising: (a) an elongate frame member, having a longitudinal axis capable of overlying a substantially planar face of said bolting flange, in a position substantially perpendicular to a longitudinal axis of said pipe, said elongate frame member comprising: (i) at least two spaced-apart contact points, positioned at one end of said elongate frame member, said contact points capable of contacting and during welding remaining in contacting engagement with said circular outer periphery of said bolting flange or said bolt hole pattern on said bolting flange; (b) a chill block, situated on said frame member between said contact points but spaced therefrom, comprising: (i) a convexly-curved outer surface, having a curvature corresponding to a desired inner diameter of said pipe and a center of curvature thereof lying on a first line bisecting and extending perpendicular to a second line extending between said two spaced-apart contact points, said convexly-curved outer surface positionable proximate said interior surface of said pipe when said frame member overlies said bolting flange, wherein said chill block is coupled to an elongate member aligned along said first line which allows said convexly-curved outer surface to be concentric with said circular outer periphery of said bolting flange or said circular bolt hole pattern in said bolting flange; and (ii) fluid inlet and outlet means for allowing cooling fluid to circulate therewithin for cooling said convexly-curved circular outer surface thereof; wherein said frame member, when said contact points thereon contact said circular outer periphery of said bolting flange or at least two bolt holes in said circular bolt hole pattern, maintains said curved outer surface of said chill block concentric with said circular outer periphery of said bolting flange or said bolt hole pattern during welding of material on said inner surface of said pipe.