Torque Striping

[bush pelican]

Is there a definitive source of information/instruction on torque striping that gives the pros/cons, techniques, dangers and limitations of this process please? Everybody seems to have an opinion but where can I find the FACTS!
Thanks BP.

[212bushman]

BP, that's a good one. I have never known that there was a critera guide line for tq striping.
Recently I have converted to using a marking pen line on the air/fuel/oil fittings of the engine. It serves me to help show what I have tightened & also as it keeps colour, can tell me about slippage creep.
212Bm

[Krystal n chips]

Are you referring to witness marks ?

If so, providing you have torqued the bolt / nut / connection or whatever to the correct value, then the witness mark should be a simple thin line painted in such way that it does not obscure any of the above and then continued onto a known fixed surface. Nowt complicated about that really....

[bush pelican]

Witness marks, torque seal, torque stripe. Yep, sounds simple, but like a lot of things in aviation, decide for yourself and get it wrong, end of career and dead people. there must be a standard somewhere.....

[bigoil]

A standard for? If its in the maintenance manual do it, if not you're choice.
Torque seal,I've heard it called anti sabotage cream. its nothing but a visual reminder that a bolt etc has been set and you have a visual ref to see if its backing offf
end of story, nothing more.

[jxk]

More to the point has anyone ever found loosen bolt (or whatever) by examining the blob of torque paint?

[Dagw00d]

I have not seen a properly tightened B-nut back off, ever... But I have seen an improperly tightened B-nut come loose with catastrophic results. The Torque Seal was applied in such a fashion that it stuck to B-Nut and overlapped the fixed portion to give the impression that nothing was wrong. It is a thick product and sometimes gives erroneous results. A second look (Independant Check) was completed on the affected line which had Torque Seal applied on a finger tight B-Nut and all was apparently done by the book. A few hours later the line backed off with the Torque Seal still visible on the B-Nut.

Not the most reliable system.

Paint in this case would have been better but it is not always easy to apply in all situations.

Nothing is foolproof.

[bush pelican]

Thanks to all who replied. Seems like information on TS is caught, not taught. I will tread carefully.

DagwOOd, is there a published incident report on that B nut you mentioned? Thanks.

BP.

[onetrack]

Torque Seal advice (http://forums.aviationpros.com/showthread.php?2893-Torque-Seal-Witness-Stripe) (best practice advice - in pics)

[grounded27]

Really??? The only reason things other than eng mount bolts get striped are for company liability! Not a difficult task, I am really surprised so many of you take it so damn seriously.

[jxk]

Always thought TS was for its 'technical' look rather than anything useful.

[cockney steve]

Maybe provoke a little thought here,- two observations.

The "acceptable " snots of sealant have a far greater purchase on the fastener than the fixed surround- therefore it can appear intact but the whole lump is moving with the fastening and only contacting the fixed surface.


One of the "unacceptable" snots actually shows a better safeguard, IMHO.
It clearly shows the fastener PAIR have not moved in relation to each other....they may be loose in the materials being fastened, but still attached to each other....(CAVEAT...see above, re-sheared interface.) any fretting would manifest itself with staining/spalling/brightups, if, indeed the fastening was loose in the materials being held.

The ideal would be a thin (runny) paint stripe going from top/side of bolt/sttud/pipe, right across the joint and onto a fixed or other surface......

That way, it's unlikely the film would lose adhesion before it cracked.

Japanese electronics LOVE these snot-lumps and i've dismantled and reinstated many joints and the snot has realigned with the clean witness patch:hmm: handy for torqueing to original, though ;)

[YOUNGBUCK]

Yes! 1 1/2 sized hyd union on l/g px line in an A320 IIRC.
The leak was not obvious due to only leaking on retraction/extension but the witness marks gave a pretty good indictor.

Also I remember reading a workshop manual once with methods of witness marking, however, I cannot remember exactly which one, possibly a lav CMM