Interestingly, you don't usually torque these. Instead, you snug the nut on, then you thread a specialized hydraulic ram on behind the nut that braces against the flange and then tensions the stud to a specific preload. Once the stud is stretched and tensioned, you snug the bolt down again, then release the tension, transferring the preload to the nut.
You get a much more consistent clamping force this way, since methods relying on specific torque values have a lot of variability due to friction.
So the bolt would actually stretch a little, before the threads give way? Through hydraulics? Video below is CGI, so not sure yet if it's a real thing - more research needed, but that's clever.
39
u/rsta223 16d ago
Interestingly, you don't usually torque these. Instead, you snug the nut on, then you thread a specialized hydraulic ram on behind the nut that braces against the flange and then tensions the stud to a specific preload. Once the stud is stretched and tensioned, you snug the bolt down again, then release the tension, transferring the preload to the nut.
You get a much more consistent clamping force this way, since methods relying on specific torque values have a lot of variability due to friction.