| 摘要 |
1,221,152. Making pipes. KABEL-UND METALLWERKE GUTEHOFFNUNGSHUTTE A.G. 9 July, 1969 [8 Aug., 1968], No. 34539/69. Heading B3A. [Also in Division F2] A method of making a thermally insulated tube comprises surrounding an inner tube with a strip coated with a self-foaming plastics foam forming material, forming a metal strip into a split tube to surround both the inner tube and the coated strip, welding the edges of the metal strip to form an outer tube and corrugating the outer tube. The strip which is coated may be a metal strip of thickness between 0À02 and 0À7 mm., particularly a steel strip between 0À05 and 0À4 mm. thickness, which may be welded to form a tube or left with an open seam. In the latter case the foam may enter the space between the strip and the corrugated outer tube. The coated strip may be of crepe paper, particularly where foaming does not occur till after the outer tube has been corrugated, whereupon the crepe paper is pressed against the outer tube thus ensuring the space between the inner and outer tubes is completely filled with foam. The pipe may be used for the transport of hot or cold fluids or as a cable conduit for superconducting cables when the inner tube is filled with liquid helium and the foam is a polyamide foam. The outer tube may be provided with a sheath of corrosion-resistant plastics material. |
