Issues with the safety valve of the equipment
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Under normal circumstances, if a device is equipped with two safety valves, one should be in use while the other serves as a backup. Should both valves be turned on at the same time? The books state that one should be in use and the other as a backup, and there must be a reason for that. Could someone explain why generally, both valves are not used simultaneously?
The installation of two safety valves on the equipment is based on two main considerations: 1. If the design takes into account long-term operation, then one valve is activated during the annual inspection of the other one. So it’s one in use and one as a backup ； 2. If the capacity of a single unit is not sufficient to ensure timely pressure relief during design, or if the diameter of such a unit is too large and there is no suitable installation location, then two units with smaller diameters can be used to replace the capacity of one unit; in this case, they need to be operated at full capacity.
It’s sufficient as long as the safe discharge volume is met; turning them all on might cause issues such as corrosion, right?
The safety valves should all be in use. I’ve never heard of any spare parts for safety accessories.
Given that safety valves need to be calibrated annually, a backup safety valve is activated when the safety valve is removed for calibration. If the discharge area of a single relief valve is not sufficient to meet the discharge requirements, consider using an auxiliary valve; both valves must be activated. The set pressure for the auxiliary valve should be 105–110% of the designated pressure (taking different operating conditions into account). If the calculated discharge area exceeds the maximum throat diameter specified in API 526, it is also possible to use two safety valves; after all, the cost of two smaller valves is less than that of one larger valve.
:victory: learned * it:victory:
Thanks, LZ; it’s very useful :):)
As mentioned by a few people above, when the capacity is high and there is no suitable installation location, two safety valves can be installed. Sometimes, the set pressure at which the two safety valves activate differs slightly; the one with the lower setting serves as the main safety valve. When the discharge is insufficient and the pressure rises, the secondary safety valve then activates. Of course, both of these safety valves must be put into use. Safety valves are generally not installed. If a backup safety valve is provided, isolation valves should be installed before and after it to facilitate disconnection.
The two safety valves are primarily subjected to online calibration: one is put into operation while the other is calibrated, thereby ensuring the safe operation of the device and extending its operational life；
It seems better to use both of them; in the event that one fails and stops functioning, the other can take over, thereby ensuring the safety of the equipment and systems to the greatest extent possible. Since two units are already available, there’s no need to have only one in operation and one as a backup. Additionally, when one valve needs to undergo annual inspection, the other serves as a backup safety valve, thereby preventing issues arising from the absence of a safety valve during production.
Both units should be put into use, right? Do they have the same pressure relief rating? I hadn’t heard that safety valves also have backups. I only heard that using both ensures absolute safety!