Correct usage of dual safety valves
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Refining and chemical processing units generally are equipped with two safety valves; how should they be put into operation? Is it one active and one standby, or are both active? Are there any regulations or guidelines? How to put it into use during the annual inspection, and so on. Please feel free to share your thoughts.
Dual safety valves are usually configured as one in use and one as a backup, meaning one is in operation while the other serves as a reserve. This ensures that if one safety valve is under repair or fails, another can take over immediately, thus maintaining system safety. In accordance with the relevant regulations and standards of ** or the region, such as GB/T 12243-2005 \"Spring-loaded direct-acting safety valves\", both safety valves must remain in good working condition during the operation of the equipment. During annual inspections or routine tests, the performance of each safety valve should be checked one by one, and necessary maintenance and calibration should be carried out to ensure their proper operation. The inspection process must strictly comply with the requirements of relevant regulations and standards. .
Both of them are in use in our factory
Firstly, the safety valves must be calibrated once a year, and this calibration must be carried out by a qualified institution. Class 3 pressure vessels generally have two safety valves. If a valve is installed below the safety valves, one person must verify that the valve is fully open, while another person must seal the valve’s handle to the valve body in order to prevent accidental operation by other workers. And keep records of who confirmed that the valve was opened and who applied the seal.
The instructions on the PID indicate that one unit should be in operation while the other is in standby mode; the inlet and outlet manual valves of the unit in operation should be fully open, the inlet manual valve of the standby unit should be closed, and the outlet shut-off valve should be open
This operation and management are rooted in the design; important container and system settings include safety valves, with one in use and one as a backup, thereby ensuring the safety and stability of system operation； As long as it is in operation, a set of safety valves must be in use ； The other group is in standby mode ； This can be effectively avoided during maintenance periods, ensuring that the device continues to operate without being affected by such periods ；
One in use and one as backup; the backup valve is sealed with a lead seal
One in use and one as backup; the backup valve is sealed with a lead seal
Both are put into operation; in some cases, two safety valves are designed with different setting pressures
That’s impossible; with both inlets and outlets fully open, there’s a slight deviation in the set takeoff pressure