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Author Topic: loose threaded fitting?  (Read 4047 times)

Coach

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loose threaded fitting?
« on: April 26, 2011, 06:29:45 PM »
I'm changing out some 3/4 inch valves on the back of my Shaver Furnace and replacing them with 1 inch valves.  I have one of the pipes coming from the furnace that seems to be slightly smaller than the others.  I tried using some extra teflon tape but still had the threaded pipe go in to the elbow too far.  Does anybody know if there is a extra heavy joint compound to make up the difference?   
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RSI

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Re: loose threaded fitting?
« Reply #1 on: April 26, 2011, 07:12:30 PM »
Are you sure the elbow didn't crack? I would try a different fitting. There is thread sealer that hardens up solid that would work if allowed to dry before putting water in it but I am not sure what it is called. I had a problem fitting one time so I took it to my cousin that works for an HVAC company and he had some good stuff.
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gspren

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Re: loose threaded fitting?
« Reply #2 on: April 27, 2011, 05:59:44 AM »
   Normal pipe threads are tapered so that they draw tight without hitting the end of either the male or female thread. Does the one that seems smaller also look like the threaded area is longer? If it looks longer its because the pipe die that cut the threads was run on too far, easy fix is to cut the end threads off untill the threaded area is the same length as the others. Don't cut too much off!
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Airgap

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Re: loose threaded fitting?
« Reply #3 on: May 27, 2011, 08:56:13 AM »
How are you changing from 3/4" valves to 1" valves?  Bushings? Red. ells?

 If by going in to far, you mean it's not getting tight the threads have been cut too deep. Pipe threads (NPT) are tapered and should make up about 2-1/2 turns by hand...

If it's not getting tight no amount of pipe dope will keed it from leaking. It would be cheaper, and the correct way, to get another nipple, or whatever fitting you are trying to install....

I would also check the thread in question with another fitting to make sure the fitting wasn't split or defective like another poster stated....
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