Liquid cargo container

Claim 1

A double-tank shipping container for general bulk liquid cargo such as crude oil, said container comprising: A a single hull sea-going vessel whose liquid-impervious hold has a prismatic formation which is spaced from the hull by a reinforcing frame to define a thermally-uninsulated outer tank capable of independently containing said liquid cargo and serving as a secondary barrier for the liquid, the deck of said vessel having an inlet port communicating with said hold; B a removable inner tank insertable in said outer tank and serving as a primary barrier, said inner tank being constituted by a collapsible bladder of flexible fabric woven of polyester material and coated with a liquid- and gas-impervious film which is a silicone-rubber elastomer which may be lowered in the collapsed state into said hold through said port, said bladder having a geometry roughly conforming to the configuration of the hold whereby those areas of the bladder that do not exactly conform to the hold are unsupported thereby, said bladder being formed of a coated fabric material of sufficient strength as to resist rupture in the unsupported areas; and C detachable means at selected positions to anchor said collapsible bladder in the hold to maintain the normal shape of the bladder when it is empty.