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Best way to seal metal threads?

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Best way to seal metal threads?

Unread postAuthor: ThatGuy » Thu Mar 21, 2013 6:32 pm

Sorry if this is a really dumb question, but I just assembled my first metal cannon but cannot get it to stop leaking. First I tried regular Teflon tape then I tried the yellow Teflon that is supposed to be made for metal pipes. I went through a roll of each after trying repeatedly to get it to seal. I tried more tape, less tape, varying thicknesses etc. but I could not get it to hold air even at 30PSI.
I am using 1 1/4" threaded metal pipes from home depot if that makes a difference.

Is the liquid sealant better? Can I still reuse the pipes later if I use the metal glue?

Any help would be appreciated.
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Unread postAuthor: CS » Thu Mar 21, 2013 7:29 pm

Go around the thread 2-3 times ensuring that it stays flat, not wrinkling. And tighten about one turn more then you can do with hand. Once the tape has been applied only tighten, once loosened the tape can be damaged and must be reapplied.

I've never used liquid sealant. No idea about the glue, but teflon tape works, your doing something wrong.

edit:
Google is your friend! Use it!

White – used on NPT threads up to 3/8 inch
Yellow – used on NPT threads 1/2 inch to 2 inch, often labeled "gas tape"
Pink – used on NPT threads 1/2 inch to 2 inch


These guys in the video use more then 3 wraps, but that isn't necessary in my experience. Also pay attention that you have to wrap it on in one direction and not the other. Watch the video to see what I mean.

http://www.youtube.com/watch?v=65i2vGWi3AE

http://www.youtube.com/watch?v=G3LMrn750Ys
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Unread postAuthor: jsefcik » Thu Mar 21, 2013 8:20 pm

Liquid is awesome dont have to worry about direction[/b]
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Unread postAuthor: ThatGuy » Thu Mar 21, 2013 10:14 pm

I wrap the tape in that way but it still leaks. How do I tighten it more than by hand? I don't have very many tools available and no workbench with a vice.
I guess I will try the pink tape though.
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Unread postAuthor: CS » Thu Mar 21, 2013 10:25 pm

How do I tighten it more than by hand?


How does I use brain? Sorry, but it is a bit ridiculous.

Image
Image

Depending on the configuration you could stick a metal bar into a T fitting, but I have no idea of the layout.
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Unread postAuthor: mattyzip77 » Fri Mar 22, 2013 12:56 pm

If teflon tape and elbow grease does not work, try some epoxy or j b weld when you thread it together..............
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Unread postAuthor: flashskate13 » Fri Mar 22, 2013 5:53 pm

Like CS has posted only way you will get a air tight seal able to handle compression is going to be with tools.
I use 3 wrap arounds of white PTFE tape then crank it as tight as possibly prefect seal no leaks.
Even if you coat them in jb weld or epoxy which I would not recommend it won't have enough strength to handle the compression and knocks, wear and tear ect.
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Unread postAuthor: speedballs » Fri Mar 22, 2013 8:24 pm

A plumber (HP gas,water) mate of mine put me onto liquid sealant. Having used Teflon tape and my muscles, ie damaged thread... liquid sealant is brilliant! Just easily nd neatly cover first two or three of the male thread hold it vertical and twist female thread on, twist it back and firth until you feel it fill the thread. You can even back it off to where you need it to sit ie triggers. Sets in 10min crures in 3hrs, comes apart with tooling, way easier to clean off than tape or epoxy. Using Boston liquid sealant all my builds have been air "tight" within 20min . Still holding 260psi 3months later. Pulled it apart yesterday for inspection and clean (over 1000 shots) 1hr from start to test fire... I've used Two types of tape and epoxy and combinations of both... Try it you'll kick yourself... plus you can just wipe off excess.. no mess.
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Unread postAuthor: ThatGuy » Fri Mar 22, 2013 10:58 pm

I will try Teflon tape and maybe use a friend's vice if wrenches don't work. Otherwise I will try liquid sealant. So liquid sealant can be removed later?
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Unread postAuthor: speedballs » Sat Mar 23, 2013 12:37 am

Cleans up heaps easier than tape!!! Works on multi metal threads... brass to brass is best. It takes a pretty good amount of effort to break the bond but the thread is always intact and sooo much easier to clean up ready to be refitted. Worked on my huge gal steel chamber, brass to S's ballvalve , 2 brass elbows that get blasted each shot with 260psi. My tape and epoxy are in the bin when it comes to sealing.

Plus you can assemble with two or four fingers as long as you have apossable thumbs :lol:

Saturday BBQ drinks don't make my spelling so neat...

3rd edit... not saying other methods don't work... sealant has worked best for my application and seems to out perform in in ease of use and re use..

P.s. I faaaaaarkin hate Teflon tape!!
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100% air tight.. excess is wiped off (doesn't cure) ball valve is trigger so every psi is pounding on this seal (1000 shots +) @ 200/260 psi.. pulled apart and put back together in under an hour. Blew my mind it worked so well and I bought the cheap brand.
IMG_20130323_180921.jpg
IMG_20130323_180921.jpg
Last edited by speedballs on Sat Mar 23, 2013 2:11 am, edited 2 times in total.

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Unread postAuthor: flashskate13 » Sat Mar 23, 2013 1:34 am

I'm going to look out for some Boston liquid sealant and give it a go, sure I will find some on eBay only thing is I have about a 1000 meters worth of Teflon tape lol.
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Unread postAuthor: mattyzip77 » Sat Mar 23, 2013 11:08 pm

flashskate13 wrote:Like CS has posted only way you will get a air tight seal able to handle compression is going to be with tools.
I use 3 wrap arounds of white PTFE tape then crank it as tight as possibly prefect seal no leaks.
Even if you coat them in jb weld or epoxy which I would not recommend it won't have enough strength to handle the compression and knocks, wear and tear ect.


You have no idea what your talking about... Epoxy will hold well over 1000 psi with ease...also if you dont have the proper tools I do not suggest that you build spud cannons.....
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Unread postAuthor: flashskate13 » Sun Mar 24, 2013 1:33 am

Epoxy is strong no denying but but it can't chemical etch to metal because metal is not pourous .
Also epoxy only gains strength when glass matt or fibre is introduce, over wise epoxy is weak brittle.
All I was saying is their are better ways !!!

also if you dont have the proper tools I do not suggest that you build spud cannons

Bit contradiction when you say its OK but with out proper tools it pointless
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Unread postAuthor: Solar » Sun Mar 24, 2013 2:24 am

Loctite Thread SEALANT, not loctite thread locker workes good too. Remember to let any liquid dry overnight though.
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Unread postAuthor: Gippeto » Sun Mar 24, 2013 2:35 am

Solar wrote:Loctite Thread SEALANT, not loctite thread locker workes good too. Remember to let any liquid dry overnight though.



Was that "not"...or supposed to be "note"?

I use blue loctite on fittings all the time. Works great. Overnight cure is a must. Dis-assembly is no problem.
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