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Discussion Starter #1
Recently ran 150' 1/2" galvanized threaded pipe for air in my work shop. Used teflon tape on threads. All fittings are tight and fully thread up. But now have several minor leaks at the threads. Don't know if the cheap Chinese flu pipe threads could be the cause or the cheap Chinese flu Teflon tape. After compessor shuts off, if I valve it off just after the compressor, it leaks down to zero in 1/2 hour. The minor leaks I have found so far should not leak down that fast.

Short of taking it apart and maybe using pipe dope, is there any other way to seal it? Any internal liquid sealers that might seal it? Also any liquid leak detectors to find any additional leaks? Soapy water works doesn't work too well for vertical fittings on top side.
 

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Can you replace the air supply, hook up a vac supply & use a hydraulic sealant on all the joints & allow the vacuum to pull the sealant into the leaks.
Just a thought, I’ve never tried it
 

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If you are getting full thread contact and using Teflon tape there shouldn't be any leaks, especially enough leakage to drain the tank in 1/2 hour. Am assuming that you have 60 or 80 gallon tank and 100+ PSI?? With that much leakage you should be able to hear the leak(s) and/or find the leak with soapy water. Is it possible that the leak is internal (within the compressor itself?
I have always used black pipe and sealed the fittings with sealer (Teflon) that comes in small tubes, never had a leak problem as long as there is full thread contact.
 

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With the cheap import shit .... gotta use both- tape and dope
 

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Discussion Starter #10
I have a valve just past the compressor, so it is isolated from the rest of the system when I close it off, not part of the leak. The 1/2 hour bleed down to zero is with the valve shut, So the 60 gallon compressor reservoir tank is not included when the system bleeds off. I have found 3 small leaks so far with soap and water, barely bubbling at all. I do have 6 air couplers to plug in air hoses and air reels and 6 small 1/4" ball condensate drain off valves. Need to recheck them. I should have used pipe dope but got talked out of it. I might get a vac pump like for A/C work and try to see if I could pull in the hydraulic sealer. Any one know a specific hydraulic sealer or maybe Locktite product that could work?

Thanks guys. Keep the ideas coming.
 

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You’re in good shape. All the air chucks in mine let it bleed down in less than 2 minutes. I just get to hear the compressor once in a while run so, I remember to close the ball valve when finished, for the day. The pump is an old Kellogg-American and it doesn’t seal perfectly either.
 

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Teflon tape is considered a lubricant in the hose and fitting industry. Designed to allow the fittings to screw further together, thusly increasing the interference in the thread to create a better seal. - A good liquid thread sealant is always better.


The vacuum idea seems decent, but not sure what sealant would cold flow well enough to accomplish what you want.
 

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When installing a natural gas heater in my garage, I was told NOT to use Teflon tape. I used Blue Monster pile thread sealer. No leaks!
 

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Discussion Starter #18
I guess I am looking for a form in place (FIP) self wicking pipe sealant that can be used with Teflon tape already installed. Maybe pulled in with system under vacuum from a A/C vac pump? Unicorn? So far google and U Tube have not found anything. Plenty of time to fiddle with under self arrest in the pole barn avoiding the government shut down craze.
 

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Discussion Starter #20
So far, many have suggested several brands of pipe sealer for assembly of fittings, including Locktite blue 242 mild thread sealer for bolts and Permatex 54540. One suggestion of slat water soaked rag for assembled fittings. One suggestion of wicking Loctite. I have not found the specific Locktite or other brand that says it can be used on assembled pipe fittings to repair leaks without disassembly.

I like the vacuum idea if i can find that mysterious product I can suck into the fittings.

I am going to make up some male air couplers with pipe plugs in the open end and see if the leak done time improves.

I have over 50 threaded joints that could possibly need fixed.
 
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