The quarter bend is threaded and has, at the threaded end, an exterior diameter of approximately 2.5" while the pipe itself is more like 2.375" OD, so I believe this is 2" PVC. It is cemented to the pipe coming from the wall.

I have been looking online and have not seen J-traps that are made to fit this pipe. Do I need to do something custom here? Is there a product that can help?

My best guess is to just cut the pipe closer to the wall, then install a reducer with a compression fitting, and then an off the shelf P-trap kit.


  • Meanwhile, put a plastic bag over that with a rubberband or tape to seal the sewer gas in the pipe, not venting out through there, unless you happen to have a plug that fits it handy.
    – Ecnerwal
    Dec 27, 2020 at 17:35
  • Thanks yes, I've had the end plugged. Dec 27, 2020 at 17:58

2 Answers 2


You can cut the existing elbow off, install a "slip joint trap adapter" on the outlet with ABS cement.


This will allow you good sliding length adjustment to a normal p trap assembly.

enter image description here

  • Noting obviously the point made by @Ecnerwal about selecting the appropriate type of adhesive. Frankly, I'm reluctant to cut a pipe except as a last resort: getting progressively closer to the wall every time something is moved around can be a major embarrassment. Dec 28, 2020 at 13:02

You have half (which is about 1/3 of, but it's one of two parts) a union trap there. Another union trap might fit it - if not, you can install the whole new union trap on the pipe.

Being black, it's almost certainly ABS, not PVC. That matters for the type of glue you use on any fittings, for instance.

Image form SupplyHouse.com - no affiliation, other than I've bought a few ting there once upon a time.

  • I'm recalling the PVC and ABS traps tend to have different sizing for the threaded portion.
    – Hot Licks
    Dec 28, 2020 at 1:39
  • Threads on plastic unions and assorted couplers aren't standard. Even from the same manufacturer, the threads might slightly change in a newer model. And even if it did, the mating might not be perfect. Considering how cheap this is (a couple dollars) I would not risk it and I would simply change the whole thing. Here, they are usually sold as a set and you can't buy just one half.
    – sleblanc
    Dec 28, 2020 at 12:58

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