METHOD OF MANUFACTURE OF COMBINED PIPE Russian patent published in 2000 - IPC

FIELD: manufacture of plastic pipes. SUBSTANCE: method includes fitting the polyethylene billet on mandrel, applying layer of sevilen on it and winding glass-reinforced plastic material followed by heat treatment and polymerization and cooling, after which pipe is removed from mandrel. Pipe billet whose inner diameter is lesser than diameter of mandrel is fitted at negative clearance or is first calibrated to size exceeding the diameter of mandrel and is fitted on mandrel at clearance, after which it is kept at relaxation till tight joint with mandrel (without clearance). Then layer of sevilen is applied, glass-reinforced material is wound, heat treatment with polymerization and cooling is conducted and finished pipe is removed from mandrel. EFFECT: enhanced reliability. 1 dwg