drainplumbingpvc
In the past, I have connected P traps just by cementing it to the wall stubout but recently have been thinking about portability in case the sink and its drain position changes. I find that, in that case, having an easily replaceable connector would be of advantage and the Fernco (rubber sleeve with a worm gear clamp) came to mind.
Is it okay to use Fernco for a portable P trap connection or should it be done with cement?
You probably won't be able to replace just half of that trap as different manufacturers use different threaded connections at the union. Assuming the "lock ring" you referred to is the union nut (the large nut connecting the two halves of the trap), hand tight is not enough so tightening it carefully with a tool was appropriate. Unfortunately it is common for the nut to crack, causing a leak at the union.
I would cut the black horizontal ABS pipe downstream of the trap and replace the trap with an adjustable P-Trap. This will require a glue joint, but will leave you in a much better position for future repair or replacement when necessary. Use only ABS cement.
Remember, hand tight is not enough. Use adjustable pliers to tighten (but not over tighten) all slip-joint fittings.
You have to cut the pipe. When re-installing you should put in unions instead of just couplings so that removing the pump is possible without disturbing the system, as the original installers should have.
Since your piping is pretty tight you will need to do some re-piping.
Here's an example:
Best Answer
This will work, but there is a specific type of fitting which is made for this purpose called a trap adapter. One end glues directly to the stub, and the other has a compression fitting that will accept the trap.
There is a big advantage of using the trap adapter over gluing. It allows easy removal of the entire trap for renovations, or maintenance. Lets say that you have the trap glued in and you want to replace the sink or counter. You would have a tough time removing the trap, and it would involve extensive plumbing work. With the trap adapter, all you would have to do is unscrew it from the wall, and from underneath the sink and the entire assembly can come out in one piece.
The adapters are also fairly inexpensive, and may even cost less than a comparable fernco fitting. The adapter is superior because it is nearly flush with the wall, and easier to remove.
Below are some examples of trap adapters. They are available in 1.25" and 1.5", which covers residential use. They are also available in PVC and ABS.