Division of pressure grades for process pipelines
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“When the pressure behind the control valve decreases, the material grade of the shut-off valve and the bypass valve located behind the control valve should be the same as that of the control valve itself; in all cases, the material grade of the upstream pipeline shall be used. ”May I ask: Which standard does this regulation come from? How to explain it?
HG/T20646 provides a detailed explanation in the section on pipeline classification; there’s a lot of information there. It’s not only related to control valves – the main goal is to ensure the safety of the pipelines as well as facilitate proper functioning of various pipe fittings before pressure is reduced. Please take your time to study it carefully. You can also consult those specializing in material control; in smaller design firms, it falls under piping work
Previously, it was divided using control valves; there was a case where the shut-off valve behind the control valve wasn’t turned on, and the consequences were obvious. Since then, shut-off valves have been used as the dividing point
Okay. . Thank you to all the experts for their answers:victory: