Messed up hose bib threads


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Old 04-10-24, 09:32 PM
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Messed up hose bib threads

I messed up the threads of an exterior hose bib. The threads appeared to be 3/4" npt. I bought a 3/4" npt die and cleaned the messed up threads somewhat. Now a 3/4" npt brass part does not screw in but a PVC part does. My plan is to apply epoxy to a PVC adapter and seal. Is there a more permanent solution?

FYI
It all started with a leak in the vacuum break. The hex screw on the vacuum break rusted and snapped off. I managed to unscrew the vacuum break but the threads got damaged.


 

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04-11-24, 04:41 AM
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Hose bibs are not NPT they are GHT. Garden hose thread.
 
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Old 04-11-24, 04:15 AM
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File bottom corner of threads at 45 degrees around circumference. Die is not doing its job.
 
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Old 04-11-24, 04:41 AM
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Hose bibs are not NPT they are GHT. Garden hose thread.
 
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Old 04-11-24, 04:45 AM
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Learn something new everyday; I've never seen that term, Sleeper.
 
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Old 04-11-24, 05:05 AM
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NPT threads are tapered. They seal metal to metal by tightening the snot out of them. Since you've used a NPT die on a hose bib the threads are shot. The sillcock needs to be replaced.

I do not see a vacuum breaker on your spigot. Was it an aftermarket one that screwed on where the hose goes? If so they have are designed to NOT be removed. They are secured in place by a screw whos head snaps off when it's tightened making it difficult to impossible to remove. It's designed to be a permenant installation to comply with code. Your new frost proof sillcock should have a siphon break built into it.
 
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Old 04-11-24, 11:09 AM
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Thank you Pilot Dane for explaining the vacuum break was not supposed to be replaced. To replace the whole thing I need to know if the hose bib connection to the water line is screwed, PEX crimped, Shark Bite, or soldered. Second, I don't want to tear the drywall to find out. This is my best attempt to just replace the vacuum break. I believe the vacuum break came with the hose bib, Arrowhead 460.

It is hard for me to believe that the code requires a permanent attachment of vacuum break. If so, shouldn't hose bibs come with brazed-on vacuum breaks?

I havent read the code But by mounting a vacuum break that would not get unscrewed with repeated hose attach-detach-ment, I think I am keeping the spirit of the code, for minimum.

The original threads on the hose bib were tapered before my rethreading. Since the female threads of the vacuum break were not damaged, I tried 3/4 npt male adapter and it fit perfectly. Could be 3/4 GHT. But I could not find GHT die. That's why I used 3/4 npt die.

I bet the code requires the use of a vacuum break, but not the type of thread. Now the thread is 3/4 npt. Any option other than a loose PVC npt adapter with lots of epoxy?

Beelzebob,
I like your suggestion of filing off the most damaged threads. I am hesitant to do so at this point, because I know a PVC adapter fits. I want to maximize the contact/seal area, not reduce.
 

Last edited by paker; 04-11-24 at 11:30 AM.
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Old 04-11-24, 11:19 AM
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Garden hose fittings do not seal on the threads. They use a rubber gasket. The threads are there to hold the hose tight against the spigot so the rubber washer can seal. So, if you have enough threads to hold, then that's all you need.

I have a hose at home I connect and disconnect frequently. To speed things up I put two washers in the hose to take up space. Now it only takes one turn of the nut to fully tighten and seal instead of the usual 6 or more turns. This is a very similar situation to what you might end up with where only a few of the threads are doing the work.

Do not file or modify the very end of the threaded area. That is where the rubber washer must fit flush to form a seal. A nick or filing it crooked can prevent it from sealing.
 
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Old 04-11-24, 01:46 PM
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You could use a NPT/GHT fitting. I searched but could not find a female NPT to male GHT fitting. You could use a NPT male-GHT male fitting with a NPT female-female coupling at the spigot. And then the vacuum breaker at the end. It will be big and may look odd but it will work. And a quick-connect on the vacuum breaker is another option.
 
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Old 04-16-24, 11:36 AM
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Finally I can use the faucet. Thank you all. No leak so far. Lesson learned: don't start diy repair without posting here. Had I asked here first, I could have reshaped the damaged threads with a file (suggested here). Also I could have tried a slip-to-GHT adapter, the slip part made soft with a heat gun to catch the threads.

 
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Old 04-17-24, 04:52 PM
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Congratulations for achieving a working fix. Do something to avoid sideways tension on the plastic to keep it from breaking.
 
 

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