Copper to PVC joint - Keeps Leaking (pics)

[AZMedia]

Hi All,

It keeps leaking, 4 attempts now, using a new PVC fitting each time. This is a copper pipe with a brass fitting on the end, and painted the house color. I'm trying to connect the PVC male fitting/pipe into this brass female but it keeps leaking, a drip every 3-4 seconds. The female threads are clean, no debris, paint, nothing.

I've tried just 3-4 wraps of teflon on the PVC, then tried 7-8 wraps, tried teflon with RectorSeal sealer, etc. I've waited 48 hours sealer to cure. As soon as I pressurize the line, which is 75PSI, the joint leaks. Any help would be appreciated. This is the line to the irrigation manifold valves. It will be under pressure at all times.

Could the brass fitting be out of round...would that cause this?

 

[AZMedia]

Some suggested this fitting should be the other way around. It should be a copper male fitting to a female PVC fitting. I looked at my own house and 2 of my neighbors homes and they are plumbed that way. I guess we got it wrong when my company originally did the plumbing for this house last year - we ran the line from the water heater to outside this wall - to a backflow preventer - to this outlet fitting.

 

[Sponsor]

 

[Reach4]

Some suggested this fitting should be the other way around. It should be a copper male fitting to a female PVC fitting.

You would not want that.

How are you going to tighten the PVC and copper tightly together, while being able to glue the PVC? Is there a lot of flex in the copper where you could lift up and down?

 

[Terry]

With PVC to threaded copper, brass or steel, it's always best to have the metal fitting be female and the plastic (PVC) be male. Plastic can split.

I normally do three wraps of tape and some pipe dope over that. Could it be a bad fitting? Yes, could be.

 

[AZMedia]

You would not want that.How are you going to tighten the PVC and copper tightly together, while being able to glue the PVC? Is there a lot of flex in the copper where you could lift up and down?

The manifold (valves) assembly is not connected to the yard lines yet, can move the PVC feed line around a little. I did picked up a PVC slip joint connector as a back up. I didn't think about the plastic splitting if PVC was the female, great point. I'm gonna try a male PVC fitting from a different manufacturer, it has some noticeable differences. If this doesn't work I'll cut and replace the copper fitting, start over.

 

[wwhitney]

If you do start over, then a threaded connection is not the only way to do a PVC-copper transition. There are also push-to-fit transition couplings (sharkbite style), a copper pipe segment with a PVC insert at one end (long enough so soldering the other end doesn't overheat the PVC insert), and there may be a compression type transition available.

Not sure if any of those are a better choice than the standard threaded transition, but thought they were worth mentioning.

Cheers, Wayne

 

[Fitter30]

Use a pvc union that way the fittings can always be.tighten. My go to pipe dope is a anaerobic doesnt matter which brand and they do cost more than regular dope. Three wrap teflon then the dope. Why aren't there wrench marks on the flats of the fittings?.

 

[Reach4]

Use a pvc union that way the fittings can always be.tighten. My go to pipe dope is a anaerobic doesnt matter which brand and they do cost more than regular dope. Three wrap teflon then the dope. Why aren't there wrench marks on the flats of the fittings?.

I think you nailed it-- too little torque.

 

[AZMedia]

Why aren't there wrench marks on the flats of the fittings?.

The picture is of the first fitting leak failure. That's why there's no marks on the copper fitting and also because I used a 12" crescent wrench on the copper, no teeth on the jaws. I tried 3 more times using a new PVC fitting each time, same brand fitting. I used 10" channel locks on the PVC. Those first couple were probably overtightened.

This is the last (4th) fitting I just removed. It had 7 wraps and rectorseal #5 on the outside of the tape.

 

[Reach4]

The picture is of the first fitting failure. I tried 3 more times using a new PVC fitting each time, same brand. There's no marks on the coppoer fitting because I used a crescent wrench - just enough to keep the toque off the solder joint. The crescent has no teeth on the jaws.

Try longer wrenches to give more torque. Or put some more effort into turning. Got another 1/4 or 1/2 turn in you? Tape + dope.

 

[AZMedia]

Maybe this is an AZ thing but I just walked the neighborhood. Each and every main line irrigation is a copper male transitioning to a PVC female. Even the original front yard valve on this house is that way. As far as tightening - at 6'2" 235lb i can assure everyone they are tight, felt like they bottomed out.

 

[Reach4]

This is the last (4th) fitting I just removed. It had 7 wraps and rectorseal #5 on the outside of the tape.

Seeing that mark on the last thread, I tend to think you are right. That copper fitting seems loose.

Would I try a denser PTFE tape, and a different pipe dope? Probably. I am not a plumber. While normally 3 turns of good tape, is enough, maybe try 7 turns of good tape.

Can you sink your PTFE tape? Pure PTFE has a specific gravity over 2. Many cheap tapes have a specific gravity that is less than 1. You might try yellow tape, although some may disagree. It is always denser than the cheapest tapes.

https://www.oatey.com/2373932/Product/Oatey-Yellow-Gas-Line-PTFE-Thread-Seal-Tape
Note that it says it is for water and more. It has a specific gravity (density) of 1.35 - 1.50 (1.35 - 1.50 grams/cubic centimeters).

Also, none of the plumbers are posting that they like Rectorseal #5 any more.

 

[AZMedia]

Thanks All. It's Done. I truly appreciate the help, I really mean that!

The threads inside the copper fitting were bad. They get really narrow in two sections opposite each, which were at 3 oclock and 9 oclock, exactly where the two leaks were coming from. It's almost as if this was a used part that was used with metal instead of PVC.



So I popped for a SharkBite. No leaks so far but time will tell after the AZ heats up those inner rubber seals to 140 degrees day after day. I'm not a fan of things you can't "tighten"

 

[Reach4]

Nice. Do protect PVC from the sun with paint or other covering.

 

[Reach4]

The threads inside the copper fitting were bad. They get really narrow in two sections opposite each, which were at 3 oclock and 9 oclock, exactly where the two leaks were coming from. It's almost as if this was a used part that was used with metal instead of PVC.

Looking at your picture, I am suspecting the threads were mated with galvanized steel, AND somebody crossthreaded while screwing the steel in.