PIPELINE WELDED JOINT UNIT Russian patent published in 2006 - IPC B23K31/02 F16L13/02 

FIELD: mechanical engineering; pipeline welded joints.

SUBSTANCE: proposed unit contains metal pipes with protective coating applied to their inner surface, sleeve placed inside pipes, ring members, ring nonreinforced and/or reinforced rubber seals, heat insulating material, sealing material, at least three-L-shaped stops uniformly spaced in radial plane or L-shaped ring stop serving for setting centers of masses. L-shaped stops or L-shaped ring stop are arranged on half of sleeve length and are rigidly fixed on its outer surface. Sleeve is provided with cylindrical section and conical sections mating with cylindrical section, expanded and/or mechanically treated by cutting-edge tool. Sleeve is arranged inside pipes so that edges of pipes are in contact with L-shaped stops or L-shaped ring stop. Protective coating is applied to inner surface of pipes at a distance from their end faces to form zone in area of application free from heat stresses. Protective coating is applied also to inner surface of sleeve. Ring members are rigidly secured on outer surface of cylindrical section of sleeve being equally displaced from its end faces. Ring nonreinforced and/or reinforced rubber seals are arranged on outer surface of sleeve between protective coating applied to inner surface of pipes, end faces of ring members and conical sections of sleeve, being held in tight contact with them. Heat insulating material is rigidly secured on outer surface of cylindrical section of sleeve between end faces of ring members, and sealing material is applied to outer surface of sleeve conical sections. Unit is formed by hand and/or automatic welding to get weld joint whose area exceeds area of normal section of pipes.

EFFECT: provision of long service life pipelines owing to protection of inner surface of weld from aggressive media.

1 ex, 1 dwg