PROCEDURE FOR CONNECTING PIPES WITH INTERNAL COATING Russian patent published in 2011 - IPC F16L13/02 

FIELD: machine building.

SUBSTANCE: invention refers to pipelines connecting. The procedure consists in forming internal layers of weld seam and head-affected zone out of corrosion resistant steel and in successive application of insulation layer on internals surface of pipe. Preliminary, under plant conditions during pipe fabrication there is introduced an additional element out of corrosion resistant steel made in form of a ring and corresponding to a section of a pipe with external diameter equal to diameter of the said pipe, while internal diameter of the section of the pipe is equal to internal diameter of the insulation layer of the pipe. The section is connected with an end part of the pipe out of carbon steel by means of laser, electric-arc or high-qualitative welding producing qualitative weld connection. Also, the end part of the pipe is formed as reinforced rings. Under field conditions pipes are connected with reinforced rings out of corrosion resistant steel by means of electric-arc welding into the pipeline to achieve welding of high quality. Notably, insulation is applied partially on internal side of the seam of rings out of corrosion-resistant steel and basic material ensuring insulation of this joint.

EFFECT: increased reliability of welded pipe connection.