| 摘要 |
A multilayer vessel or tube comprises an inner core tube and a plurality of supporting layer tubes around said inner core tube which have degassing bores. A blind layer is provided between the core tube and the innermost supporting layer tube and a plurality of core plugs rest on the core tube and are provided in a number corresponding to the number of degassing bores. The blind layer has an opening therethrough and is longitundinally split into segments and a parting channel is formed between every adjacent two segments. A core plug is positioned in central alignment with the parting channel in an opening of the blind layer. One of the supporting layers is welded only by its upper portion to the supporting layer and the core plug has a bore communicating directly or indirectly with the atmosphere. A degassing pipe is threaded into a threaded bore defined in the core plug and the core plug is provided with grooves which extend transversely along its underside, which rests on the core tube.
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