METHOD OF FORMING PIPELINE WELDED JOINT Russian patent published in 2006 - IPC B23K31/02 F16L13/02 

FIELD: mechanical engineering; pipeline welded joints.

SUBSTANCE: invention relates to pipelines used in pumping of liquid and gaseous media. Method comes to choosing to choosing of type of welded joint, preparation of edges of metal pipes to be connected by welding, application of protective coating to inner surface of pipes, placing of sealing members, heat insulating and sealing layers on outer surface of sleeve to be installed inside pipes, fitting said sleeve inside pipes and welding. Protective coating is applied to inner surface of pipes at a distance from end faces to form area free from heat stresses in zone of application. Sleeve is made cylindrical, and its butt-end zones are expanded to form conical sections. At least three-L-shaped stops are rigidly fixed on outer surface of sleeve, said stops being equally spaced in radial plane, or L-shaped ring stop. Ring members are rigidly secured on outer surface of cylindrical section of sleeve opposite to each other with equal displacement from end faces. Ring nonreinforced and/or reinforced rubber seals are used as sealing members. Protective coating is applied to inner surfaces of cylindrical and conical sections of sleeve. Heat insulating layer is rigidly secured on outer surface of cylindrical section of sleeve between end faces of ring members, and sealing layer is applied to outer surfaces of conical sections of sleeve. Sleeve is installed inside pipes to provide contact between edges of pipes and L-shaped stops or L-shaped ring stop for tight contact between ring nonreinforced and/or reinforced rubber seals, protective coating applied to inner surface of pipes, and faces of ring members and conical sections of sleeve. Welding is carried out by hand and/or automatic method with provision of weld zone whose area exceeds area of normal sections of welded pipes. Welding done, joint is cooled to ambient temperature.

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

1 ex, 1 dwg