Minor leak~what to seal with


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Old 04-28-20, 11:07 AM
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Minor leak~what to seal with

I have a 3/4" PVC MPT fitting that is in turn glued into PVC pipe below it and therefore cannot be removed.
It has a minor leak at the 3/4" fitting.
Years ago there was a tape or putty you could wrap around the outside of a metal pipe to seal minor leaks but it's been years and I don't have any idea what it's called.
If it's still out there and can be used on PVC could someone tell me what it's called?
 
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Old 04-28-20, 11:35 AM
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There are a number of wraps and miracle sealers. Most don't work like shown in the advertisements.
If your leak is all in PVC..... you should be able to cut the PVC pipe and use a coupler or union to reconnect the pipe.

A picture would be helpful too....... How-to-insert-pictures.
 
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Old 04-28-20, 11:57 AM
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The 3/4" MPT fitting is actually into a 3/4" standard irrigation valve.
I have no idea of type of plastic the valve is made of.
I originally had 4 valves hooked up with PVC unions but I could not get them to seal.
3 out of 4 hardware stores locally stocked the same unions and they were supplied with either the wrong o-rings or were very old stock as they were hard and had shrunk (or were supplied wrong in the first place) and would not seal.
After many trips to many stores I was unable to find o-rings that would work so I gave up and hard piped the 4 valves. I suspect these unions are not made in the US and perhaps that is why no standard o-ring availabe here does not work.
Now I have this one 3/4" fitting that has a minor drip. I guess i failed to tighten that one up enough when i put it in place but as stated as it in turn feeds a 1/2" PVC pipe down to the 4 valve manifold I cannot tighten the fitting at the irrigation valve.
So I must find a way to seal this minor leak. I can take pressure off the feed point so it's not wet.
PVC glue? Sealing putty? Perhaps even fiberglass cloth and resin?
I will get this sealed!
 
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Old 04-28-20, 01:16 PM
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You can try the stuff called RESCUE TAPE.
 
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Old 04-28-20, 02:01 PM
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Sorry..... I've tried several leak stop methods and have not found a reliable one.
 
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Old 04-28-20, 04:19 PM
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OK, I checked Lowes and Home Depot for Rescue Tape and found nothing. But they do carry a similar product.
As it turns out Ace Hardware, which is closer to me anyway, does carry Rescue Tape so I will give it a try.
If it fails, I think I will revert to some fiberglass cloth and resin. I have done that in the past and it worked.

Thanks for the replies.
 
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Old 04-28-20, 05:22 PM
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I've used Rescue Tape (or whatever it was called from my local hardware store) and it was a good temporary repair. (Long story with the service line into a deteriorating valve and no curb shut-off. It prevented a flooded basement over Thanksgiving weekend... but still dripped significantly.)

If it were me, I'd cut the PVC, add some more pipe dope on the threaded portion and reattach, and re-cement with a PVC coupling, and never worry about it again.
 
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Old 04-29-20, 05:11 AM
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Metal unions use metal to metal contact by compression to seal. Are PVC unions different?
 
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Old 04-29-20, 10:19 AM
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Metal unions use metal to metal contact by compression to seal. Are PVC unions different?
All the PVC unions I've used do have a rubber O-ring to help with the sealing. I'd assume the flat union surface provides much of the sealing, but due to the soft nature of PVC, the O-ring helps with the sealing.
As far as I know, the O-ring isn't intended to be compressed as much as say a 3/8" faucet hose... but I haven't analyzed one close enough to know exactly for sure.
 
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Old 04-29-20, 11:56 AM
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All I can tell you is that all of the unions I looked at in 4 different stores were much the same.
One side was flat, the other had a groove in it for an o-ring.
In the ones I bought I put a flat surface across the area the o-ring was in and it sat below the flat plane.
Now to me, if it's going to seal the o-ring should stick up just a bit.
As I was unable to find a replacement o-ring at any of 4 suppliers and was really tired of hitting the stores I just gave up and threw the damned foreign made parts away and hard piped it.
Not what I wanted but such is life.
 
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Old 04-29-20, 12:05 PM
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If it fails, I think I will revert to some fiberglass cloth and resin
Dont even go there, I'm surprised anybody would recommend a temp solution to a simple repair.

I have a 3/4" PVC MPT fitting that is in turn glued into PVC pipe
Cut the pipe, clean the cut edges install a PVC union.
The o-ring seals when water pressure exerts force on the o-ring to the other side, you are not finding bad unions that is how they work!
 
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Old 04-29-20, 03:10 PM
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Just my opinion there is no such thing as a minor plumbing leak unless it is outside on a sprinkler system. Minor leaks tend to end up as big bucks when they fail completely.
 
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