Fireproof flexible fuel tank structure

A structure for flexible tanks for fuel, comprising: a first layer (1) of fuel-resistant elastomer-based blend forming the surface of the inner wall of the tank once assembled; a second fabric layer (2) made of synthetic fiber fabric applied above said first layer (1); and a third layer (3) of fuel-resistant elastomer-based blend applied above said fabric (2), and optionally dissolved by brush with solutions of nitrile blends strengthened with resins; characterised in that it further comprises: a fourth median layer (6) of fireproof material having very low heat conductivity at high temperatures, arranged above said second layer (3); and a fifth outer layer (7) of synthetic elastomer-based blend charged with flame-retardant and intumescent products, applied above said third median layer (6).