Design Philosophy of Pressure Vessels for Service Above 10 ksi (70 MPa)

This paper discusses design criteria for pressure vessels intended for service above 10 ksi (70 MPa). Since the ASME Boiler and Pressure Vessel Code cannot, in a practical sense, be applied to the construction of such vessels, suitable supplementary and alternative criteria are proposed to serve as a design basis for such vessels. It is hoped that they can also serve as the basis for development of Design Rules for High Pressure Vessels by the ASME. Topics considered include: Use of yield strength criteria; Use of alternative fatigue criteria; Use of burst and plastic flow criteria; Alternative hydrostatic test pressure criteria; Criteria for prestressing; Material quality standards. These show that suitable criteria for high pressure vessel design require a higher level of precision than now exists in the Code. Higher levels of material quality and testing are needed to insure required minimum levels of properties without the need to compensate (by elements of the factors of safety) for excessive variation. More detailed and comprehensive analysis, to make the mathematical models more truly reflect the actual stress conditions than are usually used in Section VIII of the Code, are found to be necessary.