Quote:
Originally Posted by red-beard
Based on the limitations he's put forward, I don't see any other solution. He just doesn't have the ability to torque with the equipment he has and most of the suggestions here still need torque. With bolt heating, you control the elongation by setting the temp, then just snug and let cool. No other measurement needed. And yes, the setup will need to be designed with Inconel in mind.
Geez, I hate machining/drilling 316! 347 and Inconel are a bear!!!
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So how does this bolt heating process work? You heat the bolt to cause a change in length based on the coefficient of thermal expansion, then install and snug (when hot) at which point the cooling reduces the length and induces the preload?
One nuance in our case (besides the difficulties of actually trying to heat the bolts as I don't know how we'd do that) is that when our two parts are mated up, they are not contacting - they are spaced apart by the soft iron seal that acts as the gasket. The act of torquing brings the upper piece (the target) down and the knife edges in the lower surface of the target actually "dig in" to the iron. To control the amount of penetration, the target then comes into contact with the carriage (that it is bolted onto) and at that point any additional torque is just preloading the bolts and not inducing any additional penetration of the knife edges into the iron.
In our case, I'm not sure how well the bolt heating method would work.
We're currently leaning towards an electric torque wrench. Adjusting the torque is the biggest challenge...