| 摘要 |
A plumbing and heating pipe system for water supply purposes, made either completely or mainly of plastic material, especially of polypropylene, said system being provided with metallic connecting sleeves as well as reducers for connecting the plastic pipes to fittings of metallic materials, and being provided with shut-off valves made of plastic material and having a plastic-encased metallic valve seat for mounting in pipe lines, and being provided with pressure-type screw connections for the pipes to be joined to each other and with reducers for connection to radiators, wherein a welding device having an arrangement for equalizing the lengths of the plastic pipes is used to weld parallel plastic pipes.
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