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Discussion Starter #22
Locktite 290 is a self wicking thin liquid for locking assembled fasteners. It says it only works on metal, so I don't know if it would go into the pipe fitting threads and work with the Teflon tape. Does not say it is for pressure applications. Also don't know if it would go up into vertical fittings on the bottom side of the fitting.
 

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Years ago I had a leaking pipe joint that I needed to fix quickly. Put JB Weld on this joint and it held for many years and is probably still sealed.
 

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Black iron or galvanized pipe is still a much better choice than PVC for air lines . . . . . . . .
 

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Discussion Starter #26
Yea, I did my other shop in PVC 25 years ago and it still has no leaks. Thought this was a safer way with the galvanized pipe..If I had used the pipe dope on top of the Teflon tape, like I intended to, we would not be having this conversation, but that's on me.
 

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You should have at least 2 threads showing on all NPT fittings. If the threads are buried then you can have the threads riding up on each other and you will have leaks.

 

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Discussion Starter #30
Went thru the system again today. Put plugs into all the 7 quick connect air couplers and pipe plugs into the 6 1/4" condensate ball valves. Pressured the system. Still leaks down in 30 minutes isolated from the reservoir tank.So those 13 places are not leaking or it would have made a difference. Pressurized system again. Made up some dish washing liquid and water and used a brush and carefully applied to every threaded point I could reach easily. Found the 2 minor leaks as before and two new ones on same elbow, that may be big enough to be the issue. I let it bleed down again and cleaned those joints. Local parts store had a small tube of Permatex 29000 (Same as Loctite 290 supposedly). The self wicking fastener locking sealer for after assembly application. Applied it to the joints. Runny green stuff. Hard to say if it really went in the lower end of the vertical fittings.Test it tomorrow. At least if it does not work, the big leak can be fixed relatively easy with a saw, union, nipple and shortening the 3' pipe.
 

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Discussion Starter #32
Tested today. The 2 small leaks seem to have sealed with the Locktite/Permatex 29000 self wicking thread sealer. But the elbow that leaks on both ends still leaks. Time to get out the recip saw and cut that 3' pipe out. Thinking about making a 1/2" hose up with straight swivel ends.
 

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Teflon tape is not enough on galvanized fittings. Use pipe dope or teflon paste. And, only put it on the male fitting when assembling.
 

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Discussion Starter #38
I cut out the 30" vertical pipe next to the 90 degree elbow that was leaking at both threads.put in a 6" vertical nipple and union. Removed the old elbow and replaced with a new one and put the vertical pipe back in. I cleaned the threads of old tape, used 5 wraps of Teflon tape and covered it with Locktite 567 Teflon based thread sealer, (that I should have used in the first place) on all the joints I touched. Let set for a day. Now those joints do not leak. But the system still leaks down just as fast as before. Rechecked all the joints I could get with soapy water and brush and none of them are leaking. Need to go back and borrow the taller ladder I use before and check the rest.
 

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Discussion Starter #40
Never thought of that one. I solder copper tubing, but would it work on galvanized with teflon tape on it? Since there are no unions in the rest of the piping and it is up close to the ceiling on the walls, I might think about it. If it doesn't, I have to make a cut in the pipe to get it out anyway.
 
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