| 摘要 |
Pipe has a protective coating with an inner water-impermeable corrosion barrier layer bonded to the pipe and an outer water-permeable layer of impact and penetration-resistant cladding material with elongation not exceeding 2.2%. The cladding material has an embedded reinforcing mesh layer. - The outer layer has a continuous inner part covering the barrier layer, and an outer part which is helically slotted to the depth of the reinforcement. The slot has axially offset inner and outer regions to define a helical warp in which adjacent convolutions overlap, to permit limited bending of the pipe. The barrier layer is pref. of epoxy resin fusion bonded to the pipe. The outer layer is pref. of concrete, and a polyethylene tape may be wrapped helically around it with one edge in the slot.
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