The hydraulic test pressure for pipelines is higher than the nominal pressure
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This post was last edited by shiworkstation on 2021-11-8 at 15:20. As an example: for a heat transfer oil pipeline of grade 20#, with a design pressure of 0.9 MPaG and a design temperature of 350°C, if we use the nominal pressure PN16 (the maximum allowable pressure at 350°C is 1.07 MPaG), then what is the nominal pressure that can be chosen? Is it PN16? Is there any evidence?
For some special cases, it is better to have the design agency issue relevant documents for clarification. For reference.
Looking at the flange specifications, one of the requirements is that the hydrostatic test pressure for flanges should be 1.5 times the maximum allowable operating pressure at room temperature. If the test pressure for the piping system exceeds 1.5 times the maximum allowable operating pressure of the flanges at room temperature, then flanges with a higher pressure rating must be used.
It’s not a direct basis, but it’s useful.
This pressure rating still meets the specification requirements, but it’s right at the limit. The flange testing requirements are specified as follows: HG/T20592 11.0.2 – After the flange is installed on the pipeline or equipment, its hydrostatic test pressure shall not exceed 1.5 times the maximum allowable operating pressure at normal temperature as specified in Chapter 7 of this standard.