Regarding the pressure testing issue
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“GB6222-2005 specifies that the strength test pressure for overhead gas pipelines is 1.15 times the calculated pressure, while for buried gas pipelines it is 1.5 times the calculated pressure. The specifications for the construction and acceptance of industrial metal piping projects also specify 1.15 times. “The test pressure for the tightness test is 1.15 times the design pressure (when the test medium is air).” Does the pressure mentioned here refer to gauge pressure or absolute pressure? ? Generally speaking, unless otherwise specified, pressure refers to gauge pressure. But in previous studies, when discussing multiplicative relationships regarding pressure, only absolute pressure was considered; to date, I have not seen anywhere where gauge pressure is used in such contexts. Any experienced seniors, please tell me, hehe.
The test pressure for pipes usually refers to absolute pressure; for pressures in process engineering, it is always absolute pressure.
This post was last edited by Lao Baoli on 2010-12-20 at 12:00. It doesn’t really matter whether absolute pressure or gauge pressure is used during on-site testing, but when doing calculations, as in other process designs, absolute pressure is definitely used. I originally thought that the test pressure should also be calculated using absolute pressure. However, after checking GB50235-97, I found there clearly stated that when the design temperature is higher than the test temperature, the value Ps should be calculated using the formula Ps=1.5P×allowable stress at the test temperature/allowable stress at the design temperature. It is also specified that both the test pressure and the design pressure are in terms of gauge pressure. This left me confused, as I remembered hearing from an experienced engineer back then that absolute pressure was used! ! !