| 摘要 |
A flexible piping system for conveying a fluid, said piping system being constructed from plastics materials and comprising: - (I) an inner supply pipe (12) having an inner surface and an outer surface; and (ii) an outer secondary pipe (13) having an inner surface and an outer surface; the inner surface of the secondary pipe being a tight fit over but not bonded to the outer surface of the inner supply pipe; characterised in that the inner surface of the secondary pipe contains one or more grooves (14, 15, 16, 17) running substantially the length of the pipe (10).
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