| 摘要 |
1291390 Coating pipes by extrusion NIPPON KOKAN KK 13 Aug 1970 [25 Sept 1969] 39013/70 Heading B5A [Also in Division F2] A corrosion resistant thermoplastics layer 2, extruded on to a steel pipe 1, is protected against structural damage by the extrusion coating thereof with a further protective thermoplastics layer 3 of crenellated section. The protective layer 3 has a crenellated exterior and/or interior configuration formed by the extrusion from a similarly shaped die, and the crenellations may extend spirally of the pipe. The exterior surface of the inner corrosion resistant layer may also comprise crenellations interengaging with a similar interior surface configuration of the outer protective layer.
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