| 摘要 |
<p>1408625 Liquefied gas storage containers SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ NV 1 Nov 1972 [3 Nov 1971 27 Dec 1971 21 April 1972] 50313/72 Heading F4P [Also in Division B5] A liquefied gas storage container comprises a rigid vessel having internal insulation comprising a continuous layer of rigid foamed material which is prestressed at ambient temperature, the prestress being reduced substantially to zero at the operating temperature of the container. The layer of foamed material which is preferably polyurethane may be formed on a mould covered with a release agent, removed from the mould, cooled by, e.g. liquid N 2 , and placed in a vessel at ambient temperature, the cooled layer fitting tightly within the vessel or any gap being filled with, e.g. light concrete, or rigid polyurethane foam mixed with clay pellets. The vessel itself may act as a mould. In another arrangement a vessel or mould is lined with a layer of soft open-cell polyurethane foam coated with a resilient gas-tight layer, e.g. of aluminium-coated fibre-glass, polyethylene or rubber. A first layer of rigid polyurethane foam is sprayed on the gas-tight layer and subjected to tensile stress by sucking air from the open cell foam, to compress the latter against the vessel or mould. A second layer of rigid polyurethane foam is sprayed on the first and stressed by relieving the suction. Alternatively the prestress may be produced by forming a rigid foam layer of high glass transition temperature about one of low glasstransition temperature.</p> |
