Underwater storage tank, system of assessing the physical integrity of an underwater tank, method for detecting a loss of physical integrity of an underwater storage tank

A system for assessing physical integrity of an underwater tank, said system comprising

• an underwater storage tank for a working liquid, said underwater storage tank comprising
• a flexible multilayer tank containing said working liquid, said flexible multilayer tank being externally in contact with sea water, wherein said flexible multilayer tank comprises
• at least one internal electrical insulating layer in contact with said working liquid,
• at least one external electrical insulating layer in contact with sea water,
• at least one intermediate electric conductive layer sealed between said at least one internal electrical insulating layer and said at least one external electrical insulating layer,
• at least one first electrical connection means connected to said at least one intermediate electric conductive layer, said at least one first electrical connection means being connectable to an electrical grounded measurement instrument to assess physical integrity of said flexible multilayer tank,
• and at least one electrical grounded measurement instrument for assessing physical integrity of said flexible multilayer tank, said at least one electrical grounded measurement instrument being connectable and/or electrically connected at least to said at least one intermediate electric conductive layer of said flexible multilayer tank and to one between an electrical grounding system and said working liquid.

A method for detecting a loss of physical integrity of an underwater storage tank for a working liquid by system for assessing physical integrity of an underwater tank, said system comprising

• an underwater storage tank for a working liquid, said underwater storage tank comprising
• a flexible multilayer tank containing said working liquid, said flexible multilayer tank being externally in contact with sea water, wherein said flexible multilayer tank comprises
• at least one internal electrical insulating layer in contact with said working liquid,
• at least one external electrical insulating layer in contact with sea water,
• at least one intermediate electric conductive layer sealed between said at least one internal electrical insulating layer and said at least one external electrical insulating layer,
• at least one first electrical connection means connected to said at least one intermediate electric conductive layer,
• and at least one electrical grounded measurement instrument connectable to said at least one first electrical connection, said at least one electrical grounded measurement instrument for assessing physical integrity of said flexible multilayer tank, said at least one electrical grounded measurement instrument being connectable and/or electrically connected at least to said at least one intermediate electric conductive layer of said flexible multilayer tank and to one between an electrical grounding system and said working liquid, said method comprising:
• storing an insulation resistance threshold value of said at least one external electrical insulating layer corresponding to a loss of integrity of said flexible multilayer tank,
• detecting a current insulation resistance value of said at least one external electrical insulating layer,
• comparing said current insulation resistance value of said at least one external electrical insulating layer with said insulation resistance threshold value of said at least one external electrical insulating layer, and
• sending a warning signal for an external loss of integrity of said underwater storage tank if said current insulation resistance value of said at least one external electrical insulating layer is lower than said insulation resistance threshold value of said at least one external electrical insulating layer.

A method for detecting a loss of physical integrity of an underwater storage tank for a working liquid by a system for assessing physical integrity of an underwater tank, said system comprising

• an underwater storage tank for a working liquid, said underwater storage tank comprising
• a flexible multilayer tank containing said working liquid, said flexible multilayer tank being externally in contact with sea water, wherein said flexible multilayer tank comprises
• at least one internal electrical insulating layer in contact with said working liquid,
• at least one external electrical insulating layer in contact with sea water,
• at least one intermediate electric conductive layer sealed between said at least one internal electrical insulating layer and said at least one external electrical insulating layer,
• at least one first electrical connection means connected to said at least one intermediate electric conductive layer,
• and at least one electrical grounded measurement instrument connectable to said at least one first electrical connection, said at least one electrical grounded measurement instrument for assessing physical integrity of said flexible multilayer tank, said at least one electrical grounded measurement instrument being connectable and/or electrically connected at least to said at least one intermediate electric conductive layer of said flexible multilayer tank and to one between an electrical grounding system and said working liquid,
• wherein said at least one intermediate electric conductive layer comprises a plurality of sectors electrically insulated therebetween and wherein each sector of said plurality of sectors is connected to a respective first electrical connection means, each respective first electrical connection means being connectable to said at least one electrical grounded measurement instrument to assess physical integrity of said flexible multilayer tank at the sector to which said respective first connection means is connected, said method comprising:
• storing an insulation resistance threshold value of said at least one external electrical insulating layer corresponding to a loss of integrity of said flexible multilayer tank,
• detecting a current sector insulation resistance value of said at least one external electrical insulating layer at each sector of said plurality of sectors,
• comparing each current sector insulation resistance value with said insulation resistance threshold value of said at least one external electrical insulating layer, and
• sending a warning signal for a localized external loss of integrity of said underwater storage tank for each current sector insulation resistance value lower than said insulation resistance threshold value of said at least one external electrical insulating layer.