Galled Stainless Fittings

[Rudy]

Over the years, I've tried to migrate as many fitting as possible to Stainless due to corrosion. Stainless is expensive, but often saves me a trip up on the roof on busy days.

I've learned something the hard way though. Do not overtighten stainless/stainless fittings.

I had the large pulse dampener on my Cat 3535 start to leak from a weld failing on the side of the unit. It was attached to the 3535 with a Stainless Street El. Unbeknowns to me, it was overtightened when it was installed. It was very difficult to remove.

When I went to reinstall a replacement unit, only the first turn or so went smoothly. It was impossible to tighten it enough. I should have stopped and replaced the El. Instead, I kept going, and now the threads on the new unit have been damaged. I've ordered a 1" rethreader, and I HOPE to be able to clean up the male threads enough to get an expensive device into service.

BTW.....what are the odds of being able to clean the threads successfully???

Any advice on how to prevent the galling in the first place? We always use teflon tape on every joint....but now I think I'll use a marine grade anti-seize along with the teflon tape.

 

[soapy]

Anytime you are threading 2 stainless steel fittings you should use antiseize and go slow. Never use a air gun to tighten a stainless steel bolt and nut.

 

[Randy]

Years ago when I was working with Stainless steel fitting daily we’d use a special graphite lube when we’d make up a Stainless steel fitting to prevent it from being galled. We never used Teflon tape on Stainless steel fittings, we used a product called “Leak-lock”. Once they are galled they are pretty much history.

 

[I.B. Washincars]

Just for the record, I have just eliminated the pulsation dampers as they have failed. I can't tell the difference without them and have never had a pump failure after removing one...just so you know.

 

[mjwalsh]

Years ago when I was working with Stainless steel fitting daily we’d use a special graphite lube when we’d make up a Stainless steel fitting to prevent it from being galled. We never used Teflon tape on Stainless steel fittings, we used a product called “Leak-lock”. Once they are galled they are pretty much history.

I pretty much agree with both Soapy & Randy. On our brand new aluminum & stainless steel dog wash building we had to use many hundreds of nuts & bolts so an air tool was necessary but we went low on the air pressure to slow down the speed & the final tightening was by socket wrench. The fact that we were using stainless steel nylocks made it even more touchy. How hot the threads get I believe it a factor in the galling. Stainless steel tends to have a higher friction attribute or characteristic it seems than regular steel or brass. Pipe fittings are less touchy than stainless bolts or stainless self tapping screws.

MJ

 

[MEP001]

There's a nickel impregnated Teflon tape for stainless-on-stainless fittings. It works well. Stainless is very hard to re-thread.

 

[mjwalsh]

It seems like some of the manufacturers in the past have used zinc chromate nuts on stainless steel bolts to avoid stainless on stainless type of seizing or galling.