Bolt Lube Rcommendation
Bolt Lube Rcommendation
(OP)
Have an 18 bolt flange heated to 200 C
Taken apart often
would silver plated 5/16 UNF be better
than Grade 12.9 Cap screws with hi temp lube ???? Thanks
Taken apart often
would silver plated 5/16 UNF be better
than Grade 12.9 Cap screws with hi temp lube ???? Thanks





RE: Bolt Lube Rcommendation
Please read your post and tell us from the information you've given how would you answer it, assuming you know nothing about this flange.
RE: Bolt Lube Rcommendation
RE: Bolt Lube Rcommendation
RE: Bolt Lube Rcommendation
Rolled threads, tight tolerances, and the right materials.
I would plate the the hardware, and also require the use of a lube.
In addition to silver there is MoS, WS, and a host of other very effective surface treatments.
The problem with using a lube is that it is hard to get people to clean it every time, and hard to keep them from using too much.
You also can no longer use torque as a criteria, you will have to use tension or elongation.
You also need to think about how to set a useful life for the hardware.
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Plymouth Tube
RE: Bolt Lube Rcommendation
Silver plate is an excellent high temp coating for anti-seize on threaded fasteners. But after 1 or 2 installation/removal cycles the silver plating will be abraded off of the thread flanks. Unless you intend to replace the fastener with the silver plating (usually the nut) on a regular basis, then you'd be better off using some type of anti-seize lubricant compound that can be applied to the threads at each installation.
RE: Bolt Lube Rcommendation
We allowed nut reuse indefinitely (until the outside was damaged).
But bolts could only be used once.
Our bolts (actually studs) were all ground to a precision length and we used total elongation as a joint tightness criteria.
The mechanics hated it, but when we explained a few of the alternatives to them they got on board quickly.
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Plymouth Tube
RE: Bolt Lube Rcommendation
There was a recent incident involving titanium studs used to attach the oil filter housing of the S-92 helicopter main rotor transmission. These titanium stud threads were subject to regular removal/installation of the mating locknut when the oil filter was serviced. Over time the titanium stud threads accumulated enough galling damage to cause some of them to fail. The failure of these titanium studs attaching the oil filter housing resulted in an S-92 transmission losing its lube oil, and eventually experiencing a catastrophic in-flight transmission failure.
Problems like this can be easily prevented by taking a few minutes to check the condition of fasteners before re-using them. Or for critical applications, by simply replacing the fasteners at each installation. The cost of replacing standard fasteners at every installation is always far less than the cost of a failure caused by a worn fastener.