using pipe joint compound on plastic threads

[AdrianH]

Hi. I took my brass back flow preventer off my irigation system because I noticed it had a slow leak. I had used teflon tape so I went to the store and was given pipe joint compound and used that instead. Now it is female brass thread to male pvc thread, the pvc is the extra thick stuff.

However I just read the back of the pipe joint compound as I was putting it away and noticed it says do not use on plastic.

Whats the deal here, is it just because it might break if I try and undo it, or is it going to eat through it?

Thanks,
-Adrian

 

[phishfood]

It is dependent upon the chemical makeup of the pipe dope. If the canister says not to use on plastic, then you should not. Some are OK on PVC but not on CPVC, some on both, some are not OK on any plastic.

 

[SHR]

Use Rectorseal T+2 and be done with it. Good for use on any threads you will ever want to join.

 

[AdrianH]

Thanks for the advice. I can't get it off now though its on there so good. I don't have those slip on wrench things. What do you think my chances are if I leave it on there? It's real thick 1 inch, even if it was weakened it's still pretty strong.

If I absolutly have to take it off I am going to have to cut off the section so I can use my vice to get it off, and then couple it back together.

 

[havasu]

If this is an exterior pipe, I'd just let it go and keep your fingers crossed.