Correct Torque for Installing Burst Discs?

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madamimadam

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Valve manufacturers and parts distributors document different torque values (bold in table below) to use when installing new burst discs (valve safety assemblies/pressure relief disks) in valves:
1760043560708.png


Some third-party suppliers sell burst discs with what appear to be torque values stamped onto them. For example, Trident sells burst discs stamped with what appear to be torque ratings: "20LBf-Ft" and "30Lbf-ft” for Genesis valves (p. 50, 2025 catalog):
Trident0.png


Also from Trident, a burst disc (part AA59) stamped with “20Lbf-Ft”:

Trident1.jpeg


"20 Lbf-Ft" is 240 in-lbs or about 27 Nm, and "30 Lbf-ft” is 360 in-lbs or about 40 Nm. These values are radically different than the valve manufacturers’ installation values. Which would be the correct one to apply—the documented torque rating or the torque rating (assuming that's what that is) stamped onto the burst disc itself?
 
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