Regarding the issue of installing pressure gauges and vent valves between the rupture disc and the safety valve
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Dear experts: When the contents of the equipment are corrosive substances, a rupture disc is usually installed first, followed by a safety valve; the setting pressure of the safety valve is slightly higher than that of the rupture disc. Between the burst disc and the safety valve, regulations require the installation of a pressure gauge, but there is no requirement for a relief valve. An expert came for an inspection today and requested that a relief valve be added. I would like to ask the experts here: ① Is there any regulatory requirement for installing a relief valve? Which standard is it? ②What is the purpose of this relief valve? If it is the rupture disc that has failed, this can be detected by the pressure gauge; in such a case, simply close the main valve of the equipment and replace the rupture disc. The relief valve is not useful in this situation, and it also adds an additional sealing point. Thank you all, guys! !
Please refer to https://bbs.hcbbs.com/forum.php?mod=viewthread&ordertype=2&tid=794411
It’s not a problem. . . I’m asking about the relief valve. .
This post was last edited by altpage on 2022-7-26 at 17:17, as shown in the figure below:
①Is there a regulatory requirement for installing a relief valve? Which standard is it? I checked, and there seems to be no mandatory requirement to include this valve ②. What is the purpose of this relief valve? If it is the rupture disc that has failed, this can be detected by the pressure gauge; in such a case, simply close the main valve of the equipment and replace the rupture disc. The relief valve is not useful in this situation, and it also adds an additional sealing point. Because safety valves generally cannot achieve zero leakage (except in the case of soft-seal designs), if there is backpressure at the outlet of the safety valve, the fluid at that outlet will flow back between the rupture disc and the inlet of the safety valve. In such a situation, a pressure gauge will show pressure, and it will be necessary to manually release this pressure; otherwise, the pressure on the side where the rupture disc is located will cause inaccurate operation of the rupture disc (delayed activation)
Building 5 is the correct answer. This relief valve located between the burst disc and the safety valve serves to discharge air under normal conditions in order to calibrate the pressure zero point at that location. If an alarm is triggered due to an increase in pressure at that location during actual operation after the valve is closed, it could be either due to internal leakage in the safety valve, which creates backpressure on the burst disc, or because the burst disc has failed and is leaking.
This standard should be clearly explained; perhaps you didn’t look it up properly.
The understanding is correct; a vent valve should be added. It’s possible that the rupture disc has not ruptured, and pressure may build up in the chamber between the rupture disc and the safety valve due to leaks, so a discharge valve is needed to release this pressure.
Many of them have only a pressure gauge and no relief valve. Learned* it
I’ve learned it.* Fortunately, the project has such a design