METHOD OF PRODUCING MULTIPLE-WALL COMPOSITE PIPES

摘要

In a method of producing multiple-wail composite pipes an outer pipe (1) is diametrically expanded by heating (2) and an inner pipe (3) is diametrically contracted by cooling with a coolant introduced into the inner pipe (3) to produce between the pipes a clearance just sufficient for insertion of the inner pipe (3) into the outer pipe (1), and then the coolant is pressurized to expand the inner pipe (3) against and together with the outer pipe (1), the pressure being removed after the pipes (1 and 3) have expanded to a specific diameter of the joint therebetween. The tightness of the fit between the pipes (1, 3) due to the expansion is further increased by the subsequent thermal shrinkage of the outer pipe (1) and thermal expansion of the inner pipe (3).