Gas Sealant Question For Stainless Steel Pipe

[jcav]

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

 

[kladue]

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]

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

 

[kladue]

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]

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.

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

 

[toolboxdiver]

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

 

[jonnybravo]

I know this thread is old but how did the loctite 567 work for you?
Also how tight do you tighten stainless pipe? I was thinking hand tight then one full turn. Is that correct?

 

[sr20steve]

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

+1 on this, Teflon alone doesn't lubricate very well. I'm a pipefitter and I use teftape and a product called "silver goop" on the threads and on top of the tape. This is pretty pricey stuff but I have never had a problem galling threads since I went to this method. But if it was me and I wanted a stainless piping system I would go socket weld or tubing with compression fittings, screwed pipe is screwed lol

 

[carlisle_bob]

+1 on this, Teflon alone doesn't lubricate very well. I'm a pipefitter and I use teftape and a product called "silver goop" on the threads and on top of the tape. This is pretty pricey stuff but I have never had a problem galling threads since I went to this method. But if it was me and I wanted a stainless piping system I would go socket weld or tubing with compression fittings, screwed pipe is screwed lol

Hi

There's another version of goop called "Never Seez". Back in my pipe fitting days it was the standard stuff for any sort of stainless to stainless pipe, nut, or bolt. The only time we avoided it was when there might be a contamination issue in a chemical process.

Bob

 

[jonnybravo]

ok cool but how tight should I be tightening these 1/2 npt?

 

[OneHoppyGuy]

We use Rectorseal #5
Tight enough not to leak.

 

[jcav]

I know this thread is old but how did the loctite 567 work for you?
Also how tight do you tighten stainless pipe? I was thinking hand tight then one full turn. Is that correct?

Hey jonnybravo, the loctite 567 worked excellent for me. I plumbed my gas coming out of the gas beam with stainless steel 1/2 inch pipe and the 567 is made for sealing stainless steel. It is a little expensive but well worth it in my opinon. Heck everything on my build was expensive. I tightened mainly hand tight and then one to one and a half turns more with a wrench depending on the fitting and where it needed to be aligned.

Kladue was correct when he told me to tighten to alignment. The 567 is soft and maliable and really helps to seal the threads, even if you don't tighten the heck out of it past hand tight. It also lets you tighten a little further if needed to line up the fitting without galling the threads and locking them up. Just make sure you check for leaks. In my build I am only holding back 1/2 psi which this stuff can easily do even before it cures. It is an excellent product.

Good Luck with your build,


John