GTT Mark III Flex+

Mark III Flex is a GTT membrane LNG containment system whose primary barrier is a corrugated 304L stainless steel membrane 1.2 mm thick, not 9 percent nickel. The corrugations absorb thermal contraction at minus 163 C without high stress. The secondary barrier is Triplex, a thin aluminum sheet bonded between two glass-cloth and resin layers, laid inside reinforced polyurethane foam insulation panels. Mark III Flex thickens the insulation over the standard Mark III to cut boil-off gas, with Mark III Flex+ a further low-boil-off variant. It competes with the GTT NO96 system, which uses double Invar membranes instead of corrugated stainless.