ENAMEL-COATED PIPE WELDING METHOD Russian patent published in 2003 - IPC

FIELD: mechanical engineering. SUBSTANCE: invention relates to welding and it can be used at manufacture, repair and mounting of pipelines made of enamel-coated pipes. According to said method flat springy plates of length equal to 2/3 rods of length of pipe bore are made, with uniformly spaced lengths of wire made of corrosion resistant metal with ends projecting relative to plate. Said lengths of wire are welded to one of planes of plate. Mating slots for wire ends are made in end faces of pipe butts. Plates are bent and fitted in pipe holes arranging them symmetrically relative to vertical so that convex side with wire lengths are pointed to upper section of pipes and wire lengths are arranged longitudinally parallel to pipe axes. Then plates are relieved from bending to press additional layer of enamel to enamel coating of pipe by convex sides of plates with wire lengths to obtain enamel-filled radial clearances equal to diameter of wires between outer surfaces of plates and inner surfaces of pipes. Ends of wire lengths are bent on pipe end faces and welded flush with mating slots. Inner surfaces of pipes with bushings installed and pipe butts are covered with leveling later of flexible frit. Then pipes are assembled without clearance in butt and heated. Pipe butt joint is welded by seam of height equal to 0.8 of pipe wall thickness and then weld joint is reinforced. EFFECT: improved strength of joint and reliability of protection of seam root and pipe surfaces from corrosion. 4 cl, 2 ex, 9 dwg