Stripping threads on class 10 nut

[321GO]

[tt]I'm in a pickle...help!

I'm using a bolted connection which experiences thread stripping on the nut when reaching close to max torque value.
The bolt is a class 10.8 and the nut is class 10, to my knowledge both classes should match, right? 10 vs 10?

I've determined the torque from a generic torque sheet, of course for the corresponding pitch and friction value's present, 600Nm to be precise.

From my understanding bolts and nuts threads are designed to not shear, i.e. the bolt shank should fail before stripping, right?

How can this still be happening? [/tt]

 

[Timelord]

Another good tip is to determine clamping load from bolt stretch rather than applied torque. Infinitely more accurate if you can measure the bolt length before and after installation.

 

[321GO]

That's not option Timelord since our customers use torque wrenches, but thanks for the thought.

 

[c0rd0bes]

why not upgrade to a 12.9 screw and nut? unbrako do these