The ASME (HTL) bladder tanks can be used both as expansion tanks for sanitary systems, therefore suitable for absorbing the various volumes caused by the increase in temperature, and as autoclaves in the sanitary systems for cold water. This dual use ensures protection against corrosion of the walls of the tanks and suitability for contact with sanitary water. The tanks are composed according to the strict ASME (American Society of Mechanical Engineers) standards and issued with Stamp U or Stamp UM.