Apparatus and method for ensuring concentric weld deposition of material on a pipe interior

A method of manufacture of a pipe having a bolting flange at one end thereof, wherein an interior diameter of said pipe is formed so as to be concentric with and in a fixed diametric relation to a circular outer diameter of said bolting flange or a circular bolt hole pattern in said bolting flange, comprising the steps of:

• (A) placing a welding jig, having:
• (a) a frame member, adapted to overlie a face of said bolting flange, in a position substantially perpendicular to a longitudinal axis of said pipe, said frame member comprising:
• (i) at least two spaced-apart contact points, positioned at one end of said frame member, each adapted to contact and remain in contacting engagement during welding with said circular outer periphery of said bolting flange or with a corresponding number of bolt holes arranged on said bolting flange;
• (b) a chill block, situated substantially intermediate said contact points but spaced therefrom, adapted to receive therewithin a circulating fluid for the purpose of cooling said block member during welding, comprising:
• (i) a convexly-curved outer surface, having a curvature corresponding to a desired inner diameter of said pipe, adapted to be positioned proximate said interior surface of said pipe when said frame member overlies said bolting flange;
• over said bolting flange so that said contact points engage either (1) said circular outer periphery of said bolting flange;
• or (2) a corresponding number of bolt holes in a circular bolt hole pattern on said bolting flange, so as to maintain said curved outer surface of said chill block concentric with said circular outer periphery of said bolting flange or a bolt hole pattern thereof and a fixed distance therefrom;
• (B) welding a material, intermediate said chill block and said inner surface, to said inner surface;
• and
• (C) repositioning said chill block to a new position along said interior surface of said pipe by moving said frame and contact points an incremental distance along said outer periphery of said bolting flange or along said bolt hole pattern on said bolting flange;
• and
• (D) repeating steps (B) and (C) until weld material has been deposited along an entire inner peripheral length of said inner surface.