Theoretically, the average lifespan of a pressure balloon is around 20 years. Obviously, it is then necessary to evaluate on a case-by-case basis according to the constancy applied by the plant operators in carrying out routine maintenance, compliance with the rules for the good preservation of the roof, the professionalism of the personnel used for seasonal assembly/disassembly as well as whether the place chosen for the seasonal sheltering of the disassembled sheet is congruous to preserve its integrity.