Questions and discussions regarding the installation torque of diaphragm couplings

Each type of fastener has an optimal torque value that depends on its material, mechanical property grade, and operating conditions; if the torque is too high, the safety margin decreases, increasing the risk of breakage in emergency situations； The torque is too low, failing to achieve the purpose of pre-tensioning, and it tends to loosen easily. The bolt preload on diaphragm couplings is intended to prevent loosening and ensure more reliable transmission of shear forces (reamed-hole bolts/strengthening rod bolts); there are no external requirements for a specific preload value, like those for the round nuts used in bearings. But since the coupling manufacturer has specified the preload, it must have been determined through calculations or verified through actual use; it should be followed without making arbitrary changes, otherwise responsibility in case of problems will be unclear.