SA193 B8T CL1 bolts failing in the hydrotest condition.

[sunil8487]

I has used the SA193B8T CL1 bolts for the girth flange, for a heat exchanger that i have designed. the bolt material was specified by the client itself. it was ok in my calculations run on PVElite. But when in actual condition the hydro is being conducted the bolts are getting elongated as they are tightened and sufficient tightening is not happening. infact the bolts are stuck in the bolt holes. what is the reason that these SS bolts are not withstanding the hydro pressure. infact it is not even withstanding the design pressure.

 

[EdStainless]

Either the wrong strength and/or minimum diameter was assumed in the calculations.
Or it may be that they are not uniformly tight prior to testing. This would overload the tight ones and then as they stretched transfer load to the others.

What did you use for lubricant/anti-sieze?

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[1gibson]

Torque sequence?

 

[SnTMan]

"infact the bolts are stuck in the bolt holes" What could this mean?

Other factors: Flange & gasket surface flatness / condition. I have seen B7's tightened until they broke on out-of-flat tubesheets.

Regards,

Mike