Patent GB-942371-A (GB)
Title: Improvements in and relating to heat insulation
IPC: F17C13/00
Filed: 1962-06-12
Abstract: 942,371. Heat-insulated pipes. UNION CARBIDE CORPORATION. June 12, 1962 [June 21, 1961 (3)], No. 22450/62. Heading F2P [Also in Division F4] A container, e.g. a tank or pipeline, for the storage of low temperature liquefied gases, quick frozen biological specimens or living tissues, for example, or a container in the form of a rocket motor, comprises an inner vessel separated from an outer casing by an evacuated insulation space provided with a multi-layer insulation of low-heat-conductive fibrous material and heat-radiation-impervious material, compression means being provided for exerting a pressure transverse to the layers. The fibrous material preferably comprises fibres having diameters less than 10 microns and the radiation-impervious material has a thickness between 0.002 mm. and 0.2 mm. There is at least 4 fibrous layers per inch of insulation. The compression means may comprise tension bands extending laterally round the insulation and spaced longitudinally along the inner vessel; 4% but not less than 1% of the insulation may be compressed. The bands may be made of steel strip, Fig. 4 (not shown), the ends of each of which are secured to each other by a clip or a tension spring. Alternatively, the bands may be made of 2 mil. thick hard aluminium. In a further embodiment, Fig. 6b, the compression means comprise members 15 spaced at uniform intervals round the periphery of the insulation; each member 15 includes a spring-loaded shoe 19, the spring 17 of which extends between the shoe and a bush 18 secured to the outer casing 20 of the container. Preferably 10% but up to 20% of the area of the insulation is compressed. In a further embodiment, Fig. 9e, the compression means comprises spring-loaded shoes 38 spaced round the periphery of the insulation, the spring 43 of each of the shoes extending between the shoe and a cotter pin 47 which passes through a hole in a nipple 41, the latter being secured to a steel strap 36 extending around and in spaced relationship to the insulation. The strap 36 may be replaced by coil springs or leaf springs. In another embodiment, Fig. 10c, the compression means comprises spring-loaded shoes 38 each provided with a tube 39 telescopically disposed within a second tube 50 which is attached to a strap 36. In a further embodiment, Fig. 11 (not shown), tubes provided with shoes are spaced round the periphery of the insulation, the tubes being attached to short straps which are interconnected by springs. In other embodiments, Figs. 12 and 13 (not shown), leaf springs are spaced round the insulation and are attached to a surrounding strap. In a further embodiment, Fig. 15, the insulation comprises layers of glass fibre sheet material 75 and aluminium foil 74 and the compression means comprises a band of aluminium foil 73, the latter being disposed between layers of the insulation. The band 73 of aluminium foil may be replaced by a band of elastic material such as rubber, a flat zig-zag spring formed of high yield-point wire or discontinuous metal bands interconnected by clips or buckles. In another embodiment, Fig. 17 (not shown), similar to that shown in Fig. 15, the compression means comprises contiguous bands of low-heatconductive material and heat-radiation-impervious material such as aluminium foil disposed between the layers of insulation. Apparatus for wrapping the inner vessel 10 with the insulation and compression bands of the latter embodiment comprises a shaft 78, Fig. 16, upon which is mounted the inner vessel 10 and which is driven by a device 79, a roll 71 for the low-heat-conductive fibrous sheet material 75, a roll 70 for the heat-radiation-impervious sheet material 74, a roll 72 for the heat-radiation-impervious band material 73 and which is fitted with a friction brake 81 and rolls 83 and 84 for the low-heat-conductive band material 82. The bands 82 are preferably slightly wider than the band 73. The materials 75 and 82 are preferably made of glass fibre weighing 1.6 gms., per square foot and having fibres the average diameter of which is between 0.5 and 0.75 microns. In a modification of the embodiment described with reference to Fig. 17 (not shown), the compression means are augmented by spring-loaded members 38, Fig. 19, spaced round the periphery of the insulation 11, the spring 32 of each member 38 bearing against a surrounding metal strap 36. The inner vessel of the container may be only partially covered with the insulation.