Options for dealing with broken p-trap waste arm.

[NJW]

I had a leak under a laundry sink. The tail piece, P-trap and waste arm are chrome-plated. I had to apply a torch to the joints, but finally got the parts separated. The waste arm must have been the culprit as it crumbled where it was connected to the P-trap. The problem is that I can not remove the waste arm from the copper drain line. After applying penetrating oil and using the biggest wrench I could get back there, it dawned on me that the waste arm is likely soldered into to the copper drain line. Do I cut off the waste arm and use one of those rubber connectors (e.g., Fernco)? If so, do I leave some of the waste arm sticking out or cut it flush with the copper drain pipe?

 

[Jadnashua]

I think the best choice would be to try to unsolder the tubing from the copper. You may want to open up the wall a bit so that you can verify that you don't start something burning behind the wall, though!
The way this is usually done today is to install a Desanko, or tubing adapter on the part coming out of the wall. Here's an example of one...This then would allow you to slide new tubing into it, and then tighten the nut. Note, not shown would be a wedge shaped ring that tightens around the tubing when you tighten the nut to make the seal.

I don't think you'll find a Fernco (note, this is a brand, not a product description, but people commonly call them that) that is sized to fit over what's left as the drain pipe and the tubing are different diameters. Plus, the all rubber versions are NOT approved for interior use.

 

[Sponsor]

 

[NJW]

I think the best choice would be to try to unsolder the tubing from the copper. You may want to open up the wall a bit so that you can verify that you don't start something burning behind the wall, though!
The way this is usually done today is to install a Desanko, or tubing adapter on the part coming out of the wall. Here's an example of one...This then would allow you to slide new tubing into it, and then tighten the nut. Note, not shown would be a wedge shaped ring that tightens around the tubing when you tighten the nut to make the seal.

I don't think you'll find a Fernco (note, this is a brand, not a product description, but people commonly call them that) that is sized to fit over what's left as the drain pipe and the tubing are different diameters. Plus, the all rubber versions are NOT approved for interior use.

Thanks for the reply.

I was using "Fernco" as a generic term for a rubber connector. I know they come in different sizes for each end, so I thought that might be the easiest thing.

I guess I could put a torch on it to loosen the solder, but I was hoping to avoid that. If that is the only option however...

Luckily, the wall is open behind (basement) - so I can see what's going on back there.

 

[Reach4]

Is the pipe at the wall 1-5/8 OD copper? How far does that pipe stick out of the wall? If enough (1 inch would be good), I would get a Fernco 3001-150 shielded coupler. https://www.fernco.com/dimensional-drawings/3001-150

Cut the brass near the copper. Put the smaller end of the coupler over the copper.

Put a 1-1/2 inch PVC or ABS spigot trap adapter into the other end of the coupler. You will probably need to cut the trap arm, but that is easy.

Tighten. Put p-trap trap arm into the trap adapter.

 

[NJW]

Is the pipe at the wall 1-5/8 OD copper? How far does that pipe stick out of the wall? If enough (1 inch would be good), I would get a Fernco 3001-150 shielded coupler. https://www.fernco.com/dimensional-drawings/3001-150

Cut the brass near the copper. Put the smaller end of the coupler over the copper.

Put a 1-1/2 inch PVC or ABS spigot trap adapter into the other end of the coupler. You will probably need to cut the trap arm, but that is easy.

Tighten. Put p-trap trap arm into the trap adapter.

Thanks for the reply.

I haven't had a chance to get back there and measure the pipe. The copper pipe looks like it is sticking out of the wall about 2-3 inches.

The first commenter recommended something called a sweat adaptor. You are recommending either a shielded coupler or a trap adaptor?

 

[Reach4]

The first commenter recommended something called a sweat adaptor.

That means solder-on. Solder is good if you have a hot enough torch, and can use it without danger of burning something.

If you used a solder-on trap adapter, it would look dressier that the shielded coupling. But you would have to clean up the copper a lot, and it could be tricky to solder.

You are recommending either a shielded coupler or a trap adaptor?

Both. The shielded coupler holds the trap adapter to the copper pipe that goes into the wall. "Spigot" PVC trap adapter means that it has the same OD on the wall side as schedule 40 PVC pipe. So the coupler end meant to go onto plastic pipe matches up to the trap adapter.

Then the trap adapter lets you use "slip" drain stuff, rather than glue or threaded stuff. That means that it is really easy to install or change. Your trap and trap arm could be plastic or brass. Plastic is cheaper and easier to cut to length.

Another possibility is to use a non-shielded rubber coupler. The shielded coupler is permitted, and the non-shielded flexible coupler is not. It would function, however.

Lets be clear. The thing I am calling the copper pipe is the bigger diameter pipe and not the jagged chromed piece that is soldered into the copper pipe. The chrome piece will be 1.5 inches OD, and I am presuming the copper pipe is 1.625 OD.

 

[NJW]

That means solder-on. Solder is good if you have a hot enough torch, and can use it without danger of burning something.

If you used a solder-on trap adapter, it would look dressier that the shielded coupling. But you would have to clean up the copper a lot, and it could be tricky to solder.

Both. The shielded coupler holds the trap adapter to the copper pipe that goes into the wall. "Spigot" PVC trap adapter means that it has the same OD on the wall side as schedule 40 PVC pipe. So the coupler end meant to go onto plastic pipe matches up to the trap adapter.

Then the trap adapter lets you use "slip" drain stuff, rather than glue or threaded stuff. That means that it is really easy to install or change. Your trap and trap arm could be plastic or brass. Plastic is cheaper and easier to cut to length.

Another possibility is to use a non-shielded rubber coupler. The shielded coupler is permitted, and the non-shielded flexible coupler is not. It would function, however.

Lets be clear. The thing I am calling the copper pipe is the bigger diameter pipe and not the jagged chromed piece that is soldered into the copper pipe. The chrome piece will be 1.5 inches OD, and I am presuming the copper pipe is 1.625 OD.

Thanks for the reply. I've been away for a while and didn't have a chance to respond until now.

I did manage to remove the chrome waste arm from the copper drain. It took a high heat torch and MAP-Pro gas.

The chrome waste arm was 1 1/2 inch outside diameter and the copper drain pipe is 1 5/8 inch outside diameter.

The copper pipe sticks out from the wall 2 inches.

If I understand you correctly, I am using the shielded coupler to connect the adaptor to the copper pipe. At that point, the new waste arm (I will probably go with plastic/PVC) will simply screw onto the adaptor. Is that correct?

 

[Reach4]

If I understand you correctly, I am using the shielded coupler to connect the adaptor to the copper pipe. At that point, the new waste arm (I will probably go with plastic/PVC) will simply screw onto the adaptor. Is that correct?

The trap arm will slide into the trap adapter, and the nut will compress the washer to hold the trap arm firmly. The nut and washer come with the trap adapter.

 

[Jadnashua]

That will work, but since you have the torch, you could use a soldered adapter like I pictured in my first reply. Sometimes, the fewer pieces, the less chance of leaks.

 

[NJW]

That will work, but since you have the torch, you could use a soldered adapter like I pictured in my first reply. Sometimes, the fewer pieces, the less chance of leaks.

I understand your point and I agree that would be the more professional approach. The problem is that my soldering skills are limited. I have done it, but not in a LONG while. I was hoping to go the simplest route. The issue will be to see if I can get the required adaptor and flexible coupling to match the piping sizes that I have. My visits to the big box hardware stores just confused me even more. Perhaps a trip to the local plumbing supply shop would be in order.

 

[NJW]

The trap arm will slide into the trap adapter, and the nut will compress the washer to hold the trap arm firmly. The nut and washer come with the trap adapter.

I went to a couple of big box hardware stores today to see what they had. I did see the trap adaptor and I understand how it works. The issue will be to see if I can find a flexible coupling in the correct size (if it exists) to fit over one end of the adaptor and the end of the copper pipe. I may need to make a trip to the local plumbing supply shop for more personalized help.

 

[Reach4]

I went to a couple of big box hardware stores today to see what they had. I did see the trap adaptor and I understand how it works. The issue will be to see if I can find a flexible coupling in the correct size (if it exists) to fit over one end of the adaptor and the end of the copper pipe. I may need to make a trip to the local plumbing supply shop for more personalized help.

After further review, I see no problem.

The spigot 1.5 trap adapter will have an OD of 1.90 inches, which is the same OD as PVC pipe.

Fernco 3001-150 or equiv should do the job. On the label, "PL" means plastic, such as PVC. A little dish soap can lubricate if needed. Click Inbox above.

If you solder on a brass adapter, use Oatey No. 95 flux or similar.

 

[NJW]

After further review, I see no problem.

The spigot 1.5 trap adapter will have an OD of 1.90 inches, which is the same OD as PVC pipe.

Fernco 3001-150 or equiv should do the job. On the label, "PL" means plastic, such as PVC. A little dish soap can lubricate if needed. Click Inbox above.

If you solder on a brass adapter, use Oatey No. 95 flux or similar.

Thanks for the info.

I think one thing that may be confusing me is the difference between actual size and nominal size. That is why I think I need to actually have all the pieces in front of me to see if they fit. I have to find a Fernco coupling where one end fits over the PVC adapter while the other end fits over the copper pipe. They (Home Depot) had the Fernco coupling and the PVC adapter, but I couldn't find any piping that was 1 5/8 inch outside diameter (like my copper drain pipe). I know the brass adapter is more professional, but I am uncertain about my soldering skills. I may take a trip to the Lowes to see what they have. If all else fails, I will head to the plumbing supply shop. Hopefully, they know more than the workers at the big hardware stores and can actually show me the pieces I need...

 

[Reach4]

I think one thing that may be confusing me is the difference between actual size and nominal size.

Nominal size is what you call it -- it's a name. In trap arms the nominal size is the same as the OD. In schedule 40 pipes, both steel and PVC, it is approximately the ID. Those are "IPS" which stands for iron pipe size.

A 1.5 inch PVC pipe is 1.9 OD. A 1.5 inch copper pipe is 1.625 OD and the ID varies with the thickness of the pipe. CPVC and PEX have the same OD as copper for a given nominal size. The ID varies a lot because the material is different thickness. Those are CTS (copper tubing size).

PVC and PEX of a given nominal size are smaller than for IPS sized stuff.

The spigot trap adapter fits a 1.5 od tube on one side, and it has about a 1.9 OD on the other. It is made to be the same size OD that a 1.5 inch nominal PVC pipe has.

A hub trap adapter is made to be glued onto a pipe or equiv. You will not be getting one of those this time.