Rubber joints, in order to resist stress due to the working pressure and high temperature operation, are internally reinforced by several layers of textile fibers and of stainless steel wire, purposely woven and vulcanized, crating an only elastic body and at the same time much resistant. The body is printed with a wave single broad beam and its outer surface is protected by another layer of waterproof rubber tube that is so continuous and protects from outside. The inside edge of each folder is reinforced by a cord of stainless steel wires high resistance to increase the maximum operating pressure and ensure a good seal surface of the flanges. If placed well, the seal ensures no slippage from the body flange rubber.