| 摘要 |
PCT No. PCT/GB94/00709 Sec. 371 Date Nov. 30, 1994 Sec. 102(e) Date Nov. 30, 1994 PCT Filed Mar. 31, 1994 PCT Pub. No. WO94/22661 PCT Pub. Date Oct. 13, 1994A pipe of polyethylene is reinforced by two layers of polyethylene tape wound around the pipe in opposite directions under tension. The pipe contains carbon black and the layers are unpigmented and free from fillers and are transparent to infra-red radiation to which the first major surface is exposed. The radiation is in the near infra-red region and has a substantial part of the radiant energy of a wavelength of less than 2.5 micrometers. Very little radiation is absorbed by the layers but a very high absorption occurs in the outer surface of the pipe. This causes the interface between the second major surface of the layer and the first major surface of the pipe and between the second major surface of the layer and the first major surface of the layer to reach temperatures at which fusion welding in the layers welds them together and welds the layer and the pipe together.
|
