| 摘要 |
PCT No. PCT/FI97/00142 Sec. 371 Date Aug. 24, 1998 Sec. 102(e) Date Aug. 24, 1998 PCT Filed Mar. 4, 1997 PCT Pub. No. WO97/33121 PCT Pub. Date Sep. 12, 1997A method for joining a first tubular member to a second tubular member. The method provides a stretchable and compressible welding ring having a flexible inner ring, a resistance coil wound around the inner ring and at least one layer of plastic coating the resistance coil. The method includes the step of arranging the first and second tubular members in overlapping relation with an end of the first tubular member inserted into an end of the second tubular member and with the welding ring encircling the first tubular member and compressed between the first and second tubular members. The method also includes the step of applying electric energy to the resistance coil to melt the at least one layer of plastic so that, upon cooling, the respective ends of the first and second tubular members are welded to the welding ring. |
