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I have a drain pipe located underneath under a bathroom sink.
Half of the sewer pipe is black ABS, while the other half of the pipe is made out of white PVC.
There are no threads on either side. We cannot use a threaded nut and slip washer.
No threaded couplings may be used, unless we maybe buy something which is threaded at both ends. Both sewer pipes have the same diameter.

Maybe a straight smooth (unthreaded) coupling would work?

brhans
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Samuel Muldoon
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    How did you determine the pipes were ABS and PVC? Neither material is all that common in under-sink drains, except for wall stubouts from the house drains. Plastic piping under sinks is usually polypropylene, and can be any color. Rubber couplings are quite useful for connecting unthreaded pipe, of the same or different diameters. – kreemoweet Dec 03 '22 at 10:26
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    Normally a slip-fit trap adapter is glued to the actual drain pipe, and the trap tail (which is smaller and thinner than drainpipe) slides into that, and is clamped & sealed by it. Unless you have an inappropriate glue-in trap (those only belong under concrete in a 2" or larger size, IMHO.) – Ecnerwal Dec 03 '22 at 14:04
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    VTC; needs picture. Answer to the title as is, is the appropriate glue. Answer to the question of, ABS doesn't have a threaded fitting for attaching ***finish plumbing*** (while it may be made out of it, it is not called "PVC"), is : glue a threaded ABS (or not) fitting onto it. ... "We cannot use a threaded nut and slip washer." - because it doesn't exist, or because some code says you cannot? I don't really care, because it needs to. Unless this is an RV, then maybe it all does have to be glued. – Mazura Dec 03 '22 at 20:18

3 Answers3

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You can use 'transition cement' to make a connection between PVC and ABS for Drain-Waste-Vent applications. It's not suitable for pressure applications. You haven't provided a picture so I can't be absolutely certain, but assuming the coupler fights tightly and the rest of the plumbing makes sense, transition cement will do the job.

KMJ
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    You DO NOT want to permanently fuse drain connections under a sink. (Exception is the first fitting on the stub out at the wall where a threaded slip joint connector is fused to the stub out.) The drain pipe inside the wall will be 2 inch dia PVC or ABS. The drains from the lavatory will usually be 1.25 inch and from a kitchen sink 1.5 inch. All the connections to these pipes are made with seals under threaded compression. At the stubout the smaller diameter pipe fits inside the 2 inch drain and can be adjusted by in-and-out translation and in rotation. – Jim Stewart Dec 03 '22 at 13:11
  • Good point. I was not digging in to the question of if the cement was actually needed. I can imagine some scenario where pipe was cut off way too close to the wall. It's not going to be a common situation, though. Hopefully OP has it worked out correctly. – KMJ Dec 05 '22 at 05:11
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There are couplers available, in rubber, with a clip at each end. They're designed to join two pipes of similar o.d. I say similar, as the clips can tighten down a few mm to accommodate a slight difference in o.d. between the two. What their materials are is inconsequential. They're designed to slide completely over the end of one pipe, offer the second up, then slid back over it, before tightening up the clips - usually stainless steel. It also means any replacements in the future are made simple. No adhesives of any kind are needed.

Tim
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  • One of our bathroom lavatories is plumbed with a "rubber" reducing coupler between the 2 inch stubout from the wall to the 1.25 inch drain pipe from the trap. Not my first choice but it has lasted over 20 years. – Jim Stewart Dec 03 '22 at 19:47
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A picture of the 2 pipes you want to fit and the location are important in a proper answer to your question. As stated, cementing a connection together may not be advisable. You may need to attach a "P" trap adapter to mechanically place the drain. However we simply do not know the situation.

For a simple answer as to connection, there are "multipurpose" cements made that will bond PVC,CPVC and ABS. Cementing the 2 together with a "slip" connector is easy. Both items are readily available at bigbox and hardware stores. I have used this type of cement to bond PVC and ABS drains and vents for years with no issues.

RMDman
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  • Such "multipurpose" glues are disallowed by plumbing codes in the U.S., and I can personally attest they don't work worth a crap. – kreemoweet Dec 03 '22 at 22:52
  • @kreemoweet, those glues may be disallowed should a plumbing contractor be hired and paid tom do the job, but this is a homeowner asking how to fix his own issues. As said I have used such glue without issue for over 2 decades. Perhaps your problems stem from user error. – RMDman Dec 03 '22 at 22:55
  • being paid or a contractor has nothing to do with it. They lack approvals from the relevant agencies (IAPMO, NSF, etc) and are not allowed by code because they are not fit for purpose. – kreemoweet Dec 14 '22 at 04:17