METHOD FOR JOINING TUBES PROVIDED WITH INNER ENVELOPE Russian patent published in 2004 - IPC

FIELD: pipeline transportation systems, namely processes for joining tubes with inner coating.

SUBSTANCE: method comprises steps of placing heat insulation material between tube wall and inner envelope along the whole length of zone of active thermal influence of welding process before joining tubes by means of sleeve in such a way that to provide protrusion of inner envelope outside tube end portions by distance sufficient for fluid-tight joining of inner envelopes; then butt joining inner envelopes for further fluid-tight joining of them for example by welding; then placing sleeve with technological openings outside in zone of tube joining at uniform overlapping of tube end portions; joining sleeve ends to tubes by welding; in order to provide monolithic structure, filling inner space between ends through technological openings of sleeve with solidifying material such epoxy resin having adhesion relative to material of tube and sleeve and to material of inner envelope; using as envelope all materials designed for facing inner surface of tubes.

EFFECT: enhanced reliability, increased useful life period of joined tubes with improved fluid tightness of their joint.

2 cl, 1 dwg