loctite,oil or anti-seize ?
loctite,oil or anti-seize ?
(OP)
Don't know if this has been asked before, but here goes....
We make a highly dynamic and vibratory rotating machine that is subject to large and irregular loads.
It has various types of bolted joint connections in the form of flanges, collars, rings etc etc.
Previous designers have dictated that all bolts should be lightly oiled and be torqued to a value that puts the bolt into its elastic range.
Very occasionally we get a bolt come loose.
I argue that the bolt should be degreased and loctited - with no lock washer, and that if the bolt 'galls' when tightening that anti-seize should be lightly applied to the bolt body and under the head - but clear of the threads.
There are discussions about this method compared to the current way of working.
What is the accepted method of bolt locking in this environment ?
We make a highly dynamic and vibratory rotating machine that is subject to large and irregular loads.
It has various types of bolted joint connections in the form of flanges, collars, rings etc etc.
Previous designers have dictated that all bolts should be lightly oiled and be torqued to a value that puts the bolt into its elastic range.
Very occasionally we get a bolt come loose.
I argue that the bolt should be degreased and loctited - with no lock washer, and that if the bolt 'galls' when tightening that anti-seize should be lightly applied to the bolt body and under the head - but clear of the threads.
There are discussions about this method compared to the current way of working.
What is the accepted method of bolt locking in this environment ?





RE: loctite,oil or anti-seize ?
Did you mean to say that you tighted the bolts past the elastic range and to yield?
The light oiling is probably an attempt to reduce the scatter associated with torque control. However, oil is not really very good for that. Anti-sieze would be better for reducing scatter.
Anti-sieze and loctite do not mix. Regardless of how careful the shop is the will eventually contaminate a portion of the thread.
Have you considered Nylock type nuts, or nylon inserts in the bolts?
RE: loctite,oil or anti-seize ?
I did a contract at a company where they made aircraft valves which were subject to high vibration. There method was after tightening the bolts down they wirelocked all the bolt heads together.
regards desertfox
RE: loctite,oil or anti-seize ?
As far as I know, all the cars I've ever owned used cotter pins to ensure that the wheel nut didn't come off.
TTFN
RE: loctite,oil or anti-seize ?
Neverseez & tighten it to that the bolts are preloaded above what they'll see in service [ref. ASME PCC-1, "Guidelines for Pressure Boundary Bolted Flange Joint Assembly"; MIL-HDBK-60, "Threaded Fasreners - Tightening to Proper Tension"] & lockwire per MS33540 "General Practices for Safety Wiring & Cotter Pinning"
Also see NASA Ref. Pub. 1228 "Fastener Design Manual" for good info on locking.
RE: loctite,oil or anti-seize ?
Safety wire does not prevent loosening - it only prevents complete fastener loss and joint separation. Likewise, cotter pins on automobile drive shafts or tapered ball studs do not prevent loosening. They are passive safety devices, in that one can be assured that the joint is seated if the hole is open and can have the pin inserted.
The following previous threads provide some good information:
Thread725-340
Thread725-57042
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: loctite,oil or anti-seize ?
The only other option that you might want to try is a torque indicating bolt. Some you can look at and see if they are still in a proper stress range and some you have to hook up a probe to. Then if you don't want to use loctite you can monitor the bolts and whenever one is loosening you can retighten it. Suggestions are maxibolts or try www.smartbolts.com
RE: loctite,oil or anti-seize ?
Pre-loading the bolt shoud work well.
RE: loctite,oil or anti-seize ?
Go to “profile” then “applications” there is quite a few articles/papers on the use of the Spiralock Thread Form to mitigate problems with vibration.
http://www.spiralock.com/
RE: loctite,oil or anti-seize ?
Would jam nut be an option?
RE: loctite,oil or anti-seize ?
SBI
Central Ne.,USA
RE: loctite,oil or anti-seize ?
http://www.msha.gov/FATALS/2002/FTL02M18.HTM