SA530 Para.20水压试验计算公式中的”S"如何取值？

cui_baox

20. Hydrostatic Test Requirements
20.1 Except as provided in 20.2 and 20.3, each length
of pipe shall be tested by the manufacturer to a hydrostatic
pressure which will produce in the pipe wall a stress not
less that 60% of the minimum specified yield strength for
carbon and ferritic alloy steel pipe, or 50% of the specified
minimum yield strength for austenitic alloy steel pipe. The
test pressure or stress shall be determined by the following
equation:
P = 2St/D or S =PD/2t (3)
where:
P p hydrostatic test pressure in psi or MPa,
S p pipe wall stress in psi or MPa,


S 是屈服强度还是许用应力？

spirit_asmecn

需要达到的应力值