jcav

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Hello everyone. I am plumbing my gas lines on my stand to the Honeywell valves and needle valves with 1/2 inch stainless steel NPT thread pipe. I am going to use flex pipe the rest of the way to attach to the flare fittings on the Banjo burners. Does anyone have experience using a "thread locker" or other quality sealant on stainless steel pipes?

I have read numerous posts on the internet (plumbing websites included) that all talk about how the stainless steel threads gall and lock up easily when attached to adjoining stainless steel pipe. I have researched and Loctite 567, and 5671 PST, are made especially for sealing stainless steel pipe threads. Loctite also has a cool product called Loctite 55, which is a monofilament cord with the sealant on the cord. This cord will work also with liquid (safe for drinking water) and might be a good option for all the valves on the pumps, vessels, tees with temp probes etc. and is very clean and not messy.

Anyway I have also seen Rectorseal, MegaLoc, Permatex, Key Tite, and a slew of other products and they all have their claims on how they seal stainless steel. Has anyone on this forum used these products for sealing their gas lines on stainless steel pipes? If so I would like some feedback as to what worked for you and if it was a real hassle to seal the lines, get the fittings tight enough and positioned right, and if you ran into any problems. Some of the Loctite products are very expensive (except for the Loctite 55) and the other products are very reasonably priced. I don't mind spending the extra money if the product actually works.

Thanks for your time,

John

__________________
"Talent is hitting a target no one else can hit. Genius is hitting a target no one else can see."

"Just because your paranoid doesn't mean they really aren't after you!"

kladue

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The 2 products that we use are Loktite 567 PST and Rectorseal Tru-Blu for stainless and other metals threaded joints. These products are not the cheapest but give reliable seals even with less than perfect and rough threads. The primary thing to be aware of with stainless steel threaded joints is that they can gall up and lock with just a hand tightening.
Teflon based sealers work well if threads are perfect and pressure is low, but if things are less than optimal you usually get leaks. Teflon tape will also seal the threads but is like tossing dice, some times you are lucky and nothing happens, sometimes both parts are ruined when the threads gall up.
If you get in a situation where a threaded stainless steel joint locks up, use penetrating oil and rotate joint both directions until it binds to let oil reach all the way through the threads, then you can usually get the joint apart without destroying it.

jcav

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Thanks kladue, once again you are the man! I am going to buy the Loktite. Do you use the stick 5671 PST or the 567 liquid tube version? I really appreciate the quick reply. Most of the stainless pipes sold here are from China and Sinapore, and I hear the threads are not always perfect.

Since the threads can gall and lock up with just the tension of hand tightening, in your experience is it better lets say, when you are tightening an elbow and it gets tight on the pipe but it has to go almost another full turn to get it to line up in the right position, is it better to not go all the way around and leave it where it is when is lines up correctly, at the lessor tension? Will the Loktite make the seal, or do I have to force it to go all the way around and chance it galling up?

Thanks again Kevin

John

__________________
"Talent is hitting a target no one else can hit. Genius is hitting a target no one else can see."

"Just because your paranoid doesn't mean they really aren't after you!"

kladue

Recipes 

We use the Loktite 567 liquid version, messy as it is it does not harden up, I was just checking pressure instruments installed 6 years ago and the sealant was still soft. When tightening with sealant in place you can tighten to alignment, do not back off without pulling fitting and re applying the sealant and reinstalling the fitting. When you back the fitting off to get alignment you run the risk of having forced the sealant out and then leaving a void which can leak.

jcav

Recipes 

Excellent, I will do it this way when I install the plumbing and of course check for leaks with gas leak detector solution. Your advice is a big help!

John

__________________
"Talent is hitting a target no one else can hit. Genius is hitting a target no one else can see."

"Just because your paranoid doesn't mean they really aren't after you!"

toolboxdiver

Recipes 

I use teflon tape and the loctite dope for stainless to stainless threaded connections