RESEARCH ON THE RESIDUAL-STRESSES OF HYDROBULGED SPHERICAL VESSELS

This paper describes the residual-stress distributions of wide plate s pecimens for simulating the hydrobulging process of a 200 m(3) spheric al vessel, which latter is the first set for the storage of liquefied petroleum gas (LPG) manufactured by die-less hydrobulging technology. The results show that on the inside surface of the hydrobulged spheric al vessels, the transverse residual stress is in the compressive state : the longitudinal residual stress usually has a very small tensile va lue, but is also sometimes in the compressive state. These distributio ns of residual stresses are favourable for preventing the spherical ve ssel from stress-corrosion cracking (SCC) and embrittlement fracture a nd can improve its fatigue strength. This is a significant advantage o f the new die-less hydrobulging technology, in ensuring safety.