Hydrostatic design strength

Hydrostatic design basis (HDB) n. One of a series of 10 -h or 50-year strength values... 

Pipe analysis Hydrostatic design stress Tfensile stress at 5deld Tfensile creep ruptm stress Compression strength Critical stress intensity factor... 

TABLE 5.51 Hydrostatic Design Basis (Strength Categories) for Thermoplastic Pipe Compounds Determined with Water at73.4T (23°C)... 

Although adherence to ASTM appendixes is not mandatory, the PPI procedure was the only industry-accepted mechanism to determine long-term hydrostatic strength and hydrostatic design stress. 

It is possible to design a hydrostatic test in such a way that it probably will be a proof test of the vessel. This usually requires, among other things, that the test be run at a temperature as low as and preferably lower than the minimum operating temperature of the vessel. Proof tests of this type are run on vessels built of ultrahigh-strength steel to operate at cryogenic temperatures. 

The hydrostatic test pressure is 1.25 times the design pressure corrected for temperature, rather than the usual 1.5. Division 2 establishes upper limits for the test pressure relative to the yield strength at test temperature. The pneumatic test pressure is 1.15 times the design pressure corrected for temperature rather than 1.25 required by Division 1. Division 2 has no provision for proof tests to establish the maximum allowable working pressure. But Appendix 6, Experimental Stress Analysis, provides for the determination of the critical or governing stresses for unusual geometries for which theoretical stress analysis is inadequate. 

One practical implementation of tensile strength is in designing the thickness of objects. In calculating the wall thickness (t) of a pipe of diameter D, the relationship between the hydrostatic pressure P of the fluid that flows through the pipe and the hoop tensile stress of the material, S, is given as follows ... 

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