Premium thread torque values

[bk2]

Hello everyone,
There are published torque values for premium threaded connections (Vam Top, etc). Are they different for different metallurgy (13 Cr, 25 Cr, etc) or are they purely based on material yield? I noticed that in VAMPTS website, there is a separate selection for L80 and L80 13 Cr while populating a connection torque sheet.
Thanks

 

[redpicker]

Those torque values are calculated based on the material's minimum yield strength, the geometry of the thread, and the coefficient of friction. The metallurgy (more importantly, Cr content) can have a direct effect on the conversion coating of the threads (usually a manganese phosphate) which would have a direct effect on the friction coefficient. I am not very familiar with the VAM premium threads, so they may have developed modified coatings to get around this issue, but it would not surprise me if there wasn't different torque values based on the chemistry of the steel.

rp