METHOD OF CONNECTING INTERNALLY COATED PIPES Russian patent published in 2007 - IPC F16L13/14 

FIELD: laying and repairing pipelines.

SUBSTANCE: invention relates to nonsplit box connection of internally coated pipes for transporting chemically aggressive liquids and gases. According to proposed method of connection if internally coated pips, pipes are fitted on sealing cylindrical bushing provided with projections on outer surface, bores and sealing material and then upsetting cylindrical sleeve is fitted on butt joint of pipes from outside. Said cylindrical sleeve is provided with grooves and projections on inner surface. End faces pf sleeve are arranged from different sides of pipe butt joint. Then sleeve is subjected to reduction. Groove is made on outer surface of sealing cylindrical bushing in its center, and projection in form of ring with outer diameter exceeding inner diameter of pipes to be connected and not less than outer diameter of connected pipes by value not less than reduction value in made in center of groove. Projections are made before and after groove. Sealing material is arranged on outer surface of sealing cylindrical bushing. The rest of surface of sealing cylindrical bushing is coated with protective layer. Rubber sealing rings are fitted on surface of projections in grooves. First projection on inner surface of upsetting cylindrical sleeve is made in center with height equal to depth of groove on outer of sealing cylindrical bushing and of width less than width of groove on outer surface of sealing cylindrical bushing by value equal to double thickness of wall of connected pipe. Grooves are made before and after first projection with depth equal to height of projections of sealing cylindrical bushing and width exceeding width of projections of sealing bushing by value equal to double thickness of wall of connected pipe. After grooves, second and third projections are made of height equal to depth of groove on outer surface of sealing cylindrical bushing. When assembling the joint, upsetting cylindrical sleeve is fitted on pipe over entire length, sealing cylindrical bushing is inserted pipe to thrust against limiting ring, second pipe is fitted on sealing cylindrical bushing to thrust against limiting ring, upsetting cylindrical sleeve is moved onto butt and is aligned following previously made marks, then reduction is carried out to form lock joint between projections and grooves of upsetting cylindrical sleeve, pipes and inner coating of connected pipes and sealing cylindrical bushing.

EFFECT: improved reliability of connection.

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