Removal torque
Removal torque
(OP)
I suspect too much torque has been used to assemble some pipe couplings.
If you know how much torque was required to undo a threaded connection, is there a rule of thumb you can use to get some idea of how much torque was used to do it up in the first place?
A.
If you know how much torque was required to undo a threaded connection, is there a rule of thumb you can use to get some idea of how much torque was used to do it up in the first place?
A.





RE: Removal torque
In industry, it has been found that the best procedure is to verify the torque in the "on" direction. A typical procedure is to take a previously tightened, at-rest fastener and advance it in the tightening direction less than 5 degrees and record the maximum torque. This should compare fairly well (+/- 20 %) to the original tightening torque. This assumes there aren't large changes in joint behavior (embedment, corrosion, etc.).
Regards,
Cory
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RE: Removal torque
RE: Removal torque
RE: Removal torque
Usual problem is that this is diagnosis from the far end of a not very good telephone line, so I'm left (again) with trying to interpret the results of someone else's test.
If I interpret Cory's first paragraph correctly, it would be a bit suspicious to find an "undo" torque nearly three times the specified assembly torque (on a reasonably clean component).
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RE: Removal torque
Was there any pipe compound applied initially?
TTFN
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RE: Removal torque
A.
RE: Removal torque
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Removal torque
Regards,
Cory
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: Removal torque
A.
RE: Removal torque
*awaits criticism*
RE: Removal torque
Too late now to do much about it (everything's in bits, even the stuff that didn't disassemble itself) - but thanks for teaching me something new.
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RE: Removal torque
A very experienced guy told me at the time that very rough rule of thumb was undo torque = 1.5 X fastening torque.
Obviously we had something else going on.
KENAT, probably the least qualified checker you'll ever meet...