Fremgangsmåde til kontinuerlig fremstilling af et dobbeltvægget korrugeret rör med rörmuffe, det dobbeltvæggede korrugerede rör samt et apparat til udövelse af fremgangsmåden

摘要

The method involves extruding external tube (37) and internal tube (39). The internal tube and troughs (40) of external tube are welded together and external tube is expanded to form expanded area for pipe socket (41). A transition portion (61) is formed between pipe socket and adjacent trough and area between internal and external tubes is vented into adjacent elevation (38) in the vicinity of transition portion. Independent claims are also included for the following: (1) twin-wall pipe; and (2) apparatus for manufacture of twin-wall pipe.