Joining Schedule 40 PVC and metal


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Old 07-01-07, 03:17 PM
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Joining Schedule 40 PVC and metal

I replaced the piping around my sprinkler system vacuum breaker. Where the metal nipple goes into a threaded Schedule 40 PVC female fitting, I have a leak. I used teflon tape, but was concerned about cracking the fitting by over-tightening and may not have run it in as hard as possible.

My question is: when I re-do this, is there a metal-to-PVC pipe dope that would be better than the teflon tape? And is there a rule of thumb for avoiding cracking the plastic part you are running the metal into?

Great forum, as usual.

-Gary
 
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Old 07-02-07, 11:04 PM
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Use a teflon paste that is listed (read the can or tube) for use with plastic pipe.
 
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Old 07-03-07, 06:53 AM
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Just a point of interest.

There was a time that PVC female couplers were not a legal connection because of the cracking associated with these joints. (just because a fitting is made does not make it legal) I know this is about a sprinkler system and doesn't really fall under the plumbing code, per se, but for a future reference. Check the local code to see if this is an allowable connection.

Furd: your not a plumber, we don't read directions or labels....Good call.

Not all pipe dope is created equal so follow Furd's advice.
 
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Old 07-03-07, 07:44 AM
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Good info; should I re-do with male fittings?

Thanks to furd and notuboo. I was trying to rebuild this piping exactly as it had been, and your feedback confirms my suspicion about the plastic female coupler. Since I am connecting the Schedule 40 to metal ball valves with female threads, maybe I should revise the plan and use male fittings, which I take it are preferable.

Gary
 
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Old 07-03-07, 10:30 AM
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Nope, I'm not a plumber. I am a retired engineer but I have made more threaded pipe connections than I care to remember. I have seen (and used) some plastic female thread adapters that have a steel band on the outside but I agree that if one can avoid using plastic female adapters that is the best solution.
 
 

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