Cutting into a pipe to add a fitting: a tight spot

[Theodore]

I have to add a wye onto a vertical 4” pvc drain pipe in my wall. There’s a 90degree horizontal –to-vertical turn elbow at the top of this pipe, so I expect almost no wiggle room in pushing up. And a similar vertical-to-horizontal turn at the bottom of this pipe. If I cut and remove just enough of the vertical pipe (as measured by the new fitting's inner-hub to inner-hub dimension) , I’m concerned that I wont be able to push the two vertical cut ends apart enough to install the fitting. Is there any trick to this? Or just keep cutting off a little more and push apart really hard until it fits and grabs at least “a little”? And if so, what's a good definition of "a little"?

Advice appreciated.

Thanks

 

[Jadziedzic]

Glue 6-inch long lengths of PVC into the top & bottom of your wye, then cut the original pipe to allow the wye and stubs to fit into place. Use shielded couplings (aka "Ferncos") to connect the wye to the free ends of the original pipe.

 

[Sponsor]

 

[CountryBumkin]

I'm not a plumber - so maybe I'm not visualizing your issue correctly. Wouldn't you just use a Fernco coupler (with a smooth inside) on the top and bottom of the new pipe. Of course you would want to ensure the existing pipe won't move/slide-down under its own weight (maybe add strapping) once you cut out a section.

So you have a new fitting say it's 8 inches long, then you cut out a section of the existing pipe 8 inches in length, slide a Fernco "up" onto the existing pipe, and a second Fernco is slide "down" onto the existing pipe, then once the new pipe section is inserted, the Ferncos are repositioned half way over the cuts and tightened.
https://www.fernco.com/plumbing/flexible-couplings

 

[Theodore]

!!!! I never even thought of such a simple, elegant approach. I was sweating and worrying that I'll be there with crowbars and hear pipes cracking off in the distance. Thanks so much.

 

[Dj2]

Just a quick advice: Don't cut anything before you get your parts. make sure the couplings that you get are for PVC (OD size matters).

 

[Gary Swart]

You also need to specify no hub-or banded coupler. The sleeve with just 2 hose clamps is not approved of above ground use. Fernco is a brand name for many different fittings including the no-hub.

 

[hj]

You CANNOT just slide the coupling over the tee. It will NOT fit.

 

[Master Plumber Mark]

You CANNOT just slide the coupling over the tee. It will NOT fit.

HJ...just stand back and watch the human drama and struggle happen


I really want to see the video of this.... please have someone filming you with their cell phones

This ought to be good entertainment........



something I suggest if this is on a verticle run....it would be wise to figure out a way to
support and secure the pipes before cutting a section out...

 

[Dj2]

You also need to specify no hub-or banded coupler. The sleeve with just 2 hose clamps is not approved of above ground use. Fernco is a brand name for many different fittings including the no-hub.

Yes, for a vertical pipe you have to use a no-hub or shielded coupling.

 

[Theodore]

Well, one cannot slide the coupling over a hub of a fitting. But if it's a street fitting, I suppose I could slide the coupling over the spigot of the street fitting, right?

 

[Reach4]

You put the loose couplings on the pipes before inserting the the new assembly. If the surviving segments of the old pipe are not going to be long enough to hold the loose couplings, you will make the pipe segments glued the new wye long enough.

If you were proposing to try to grab a street fitting with the coupler, I think you need to have each coupled pipe go into the coupler pretty much half way.

 

[Smooky]

You need to glue a short section of straight pipe into the hub so you can use the shielded no hub coupling. Another option would be to use fittings that do not have hubs. Then you can use shielded no hub couplings to connect to other fittings or directly to straight pipe.

 

[hj]

The only fittings WITHOUT hubs, are No-Hub cast iron.

 

[Jadnashua]

You want banded couplings. As already mentioned, if you glue stubs into your fitting(s), and cut enough straight pipe away so that the new stuff with the stubs on it would fit, you then connect them together with the banded couplings. Ideally, you don't want large gaps, so, to get the couplings in place, loosen the bands enough to slide the reinforcement sleeve up or down away, you can then fold half of the rubber back on itself, position the assembly into alignment, roll the rubber back into place, slide the metal reinforcement into place, then tighten the clamps and you're done.