When the number of safety valves on a spherical tank is ≥2, is it necessary for their setting pressures to have a gradient?
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When the number of safety valves on a spherical tank is ≥2, is it necessary for their setting pressures to have a gradient? I heard it said that way, but I can’t find any relevant regulations
Not necessarily; if they are backup safety valves to each other, then they are exactly the same. In the case of primary and secondary safety valves, the set pressure of the secondary safety valve is 1.05 times that of the primary safety valve (under non-fire conditions), or 1.1 times (under fire conditions).
Thank you for your reply. May I ask which standard your response is based on? The petrochemical standard series QS/T specifies that if two or more safety valves are installed on a spherical tank, the setting pressures of these safety valves should be arranged in a gradient manner；
ASME VIII “Boilers and Pressure Vessels”
There are steps on the 2 safety valves of the boiler