| 摘要 |
PROBLEM TO BE SOLVED: To eliminate uneven subsidence of a cold insulation material, prevent degradation in cold insulation function, and, further, reduce restraints on thermal expansion in the returning of an inner tank from a low temperature to an ordinary temperature, by providing a plurality of ringlike partitions into the double shell of a tank roof and by filling the cold insulation material into spaces enclosed by the partitions and double shell. SOLUTION: An outer-tank ringlike frame 13a has five rings and, below it, partitions are provided in a ring form. The partitions each comprise a net 28 made of stainless steel or the like, and glass wool 29 attached to the net 28. The upper end of the net 28 is fixed to the lower end of the outer-tank ringlike frame 13a, and its lower end is fixed to an inner-tank roof shell 7. Between each partition and a pearlite diaphragm, granular pearlite 17 is filled as far as an outer-tank roof shell 12. Therefore, although uneven subsidence occurs between the rings in some degree, the thickness of the granular pearlite 17 becomes even as the entire roof because a ring interval is narrow. It prevents degradation in cold insulation performance and reduces restraints on the expansion of an inner tank 2 during the inspection of its inside.
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