Should isolation valves be installed before and after the safety valve of a pressure vessel? If not, what should be done during the maintenance of the safety valve?
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Should isolation valves be installed before and after the safety valve of a pressure vessel? If not, what should be done during the maintenance of the safety valve?
On some pressure vessels, the safety valve is connected directly to the vessel, without a shut-off valve in between. During the annual inspection of safety valves, it is usually done during shutdown for maintenance; in such cases, the medium inside the container is drained or the pressure is reduced to atmospheric level.
The pressure vessel management regulations stipulate that no valves are allowed to be installed before or after the safety valve; violations of this rule result in fines. Our approach is to use offline backups; when the verification deadline is approaching or individual issues are detected, those units are taken out for verification, shutdown for maintenance, or replaced by alternative units. ——It is not allowed to use equipment with problems in its safety accessories. Incidentally, safety valves with lower pressure often fail to return to their original position after activating, which is a rather troublesome issue.
Two safety valves can be installed, one online and one offline, with the isolation valve in front of the safety valves locked in either the open or closed position.
Now, double valves are used, with shut-off valves at the front and back, as well as a bypass line.
Safety valves can be inspected online; simply contact the special inspection agency to submit a request.
The rule is that hand valves are not allowed to be installed in front of or behind the safety valve; however, generally a hand valve is installed in front of the safety valve and kept open, while there is an air release outlet behind the safety valve with no hand valve installed there.
Does the tolerance specification have such a requirement? I hadn’t noticed yet. Could you take a screenshot to show me?
Safety valve: If you add a valve in front of it, can it still be called a safety valve? There must not be any valves between the equipment and the safety valve. If a safety valve trips every day, you should look into issues related to your operational procedures rather than seeking problems with the safety valve itself. Safety valves are registered with the safety department; they cannot be repaired at will. There is a specified lifespan for them, and when that time comes, the safety department will get in touch with you. It can only be replaced if the system is overpressured and the safety valve does not activate, or if it activates even at normal pressure.