Overstressing of pressure retaining vessels using the stress test is realized as a high-pressure test that theoretically would introduce into the material sufficiently high membrane stresses, whose values are above the yield stress but lag sufficiently behind the strength of the material. Pressure tests using overstressing are realized mainly on equipment with long life operation, where maximum safety and reliability is required. Their aim on one hand is to test the pressure bearing capacity of the equipment and on the other to create stress barriers against the initialization of cracks and their under-critical length growth respectively, and thus improve the material and safety of this equipment for their further operation. In this paper we present briefly our experience in the theoretical field (analytical and numerical determination of the pressure value including its distribution over the spherical vessel) as well as during the test of a spherical pressure-retaining vessel of 12.5m diameter filled with liquefied hydrocarbon gas.
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