Low temperature liquid storage tank of the internal heat insulating type having leakage detecting means

Claim 1

An internally thermally insulated low temperature liquid storage tank with leakage detecting means, comprising: a tank shell; a liquid impermeable layer lining the tank shell; A layer of thermal insulation interposed between the liquid impermeable layer and the shell; a secondary liquid impermeable barrier layer provided in the layer of thermal insulation, intermediate the thickness of the thermal insulation; a layer of gas permeable sheet material located within the layer of thermal insulation next to the side of the secondary liquid impermeable barrier which faces inside the tank; a plurality of gas impermeable partition members extending through the thickness of the gas permeable sheet material and dividing the gas permeable sheet material into a plurality of minor compartments; the minor compartments being grouped into a plurality of major compartments; a plurality of conduit means extending through the partition members, each conduit means serving to intercommunicate the minor compartments of a respective major compartment; means for continuously pumping a supply of inert gas through selected ones of the respective major compartments via the respsective conduit means and for collecting said gas thereafter; the collecting means including a gas analyzer for detecting the presence in the collected inert gas of leakage from the inside of the tank through the firstmentioned liquid impermeable layer into said gas permeable sheet within any major compartment; minor compartment being provided with a plurality of rigid posts extending through the thickness thereof, these posts being spaced from one another and from the partition members within each minor compartment to prevent the flow of said inert gas therethrough from said conduit means to said collecting means; and the pumping means including automated control means connecting the pumping means to the gas analyzer and set to automatically increase the rate of pumping of inert gas through any major compartment into which the interior of the tank is sensed to be leaking, in order to carry away the leakage and so retard the progress of such physical damage as has resulted in the leakage.