Stud Bolt Torque Question

[shannonb2135]

I found a chart with recommended torque values for ASTM A193 B7 bolts for use with carbon steel flanges but how are the torque values affected when using the same bolts with CuNi flanges? It seems like different flange materials would require different amounts of clamp load.

 

[Duwe6]

Actually, no. The required clamping force is dictated by the pressure, temperature, and viscosity of the material in the line, and by the material and thickness of the gasket.

The thing to watch for with CuNi flanges is to not use too high a torque value. B-7's are strong enough to bend the flanges.

 

[rmw]

Actually yes, but Duwe6 after stating no does answer your question and the answer is yes.

I notice that the Fastenal chart you have found is based on 75% of yield while some companies have lower standards. Where I work, we are limited to 60% of minimum YS so we would calculate the bolting accordingly and torque to a lower value.

Read about the thread lubrication too. It makes a lot of difference.

rmw