Hi-Temp Stainless Thread Lube 2

[Duwe6]

We have a 304-bodied slide valve that bolts up to pipe flanges using tapped holes in the body. Valve runs at about 1100°F for 1 to 4 months. Bolting currently in use is also 304 s/s.

We have tried Milk of Magnesia, FelPro C5A never-seize, and ceramic coating the bolts. Nothing works well. Suggestions, please?

 

[moltenmetal]

Henkel Loctite brand nickel antisieze paste is what we use for high temperature break-out lubrication. Have no experience with the FelPro brand- if it's the same stuff, then you've already tried it I guess. Nickel antisieze either works, or you're going to be in trouble unless you can also change metallurgy of one of the parts.

 

[tbuelna]

I agree with moltenmetal's suggestion to use a different bolt material, if possible. Using a harder bolt material, such as A286 cres, will reduce the thread galling problem you are experiencing.

Personally, I don't like paste type anti-seize compounds for use on screw threads with most applications. Primarily because the anti-seize paste gets wiped off the thread contact surfaces it is supposed to prevent from seizing during installation. A dry-film coating like moly disulfide, some type of plating like silver, or coatings like IVD aluminum work better since they are more durable and are far less likely to be scraped from the thread surfaces during installation.

 

[EdStainless]

PVD coating with tungsten dislufide is an option (better high temp than MoS2).
After you change the bolt metallurgy, that needs to be done.
But at 1100F you cant use a cold worked bolt. A 17-4PH with H1150 heat treatment would work, or A286 (alloy).
You could also try boron nitride. I never left any for that long but it did work (coating both the hole and bolt) for a few weeks at 1000F.

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P.E. Metallurgy, Plymouth Tube

 

[FennLane]

We always used Boron Nitride dags for coating the threads and collets used in the high temperature tooling we supplied with both creep and LCF test machines and generally had good success with parts that may have been preloaded at temperature for the extensive periods of time associated with this type of testing.

WE used this treatment for tolling used up to 1150degC.