How should I replace this ABS p-trap and drain?

Question

I just replaced a faucet and drain on a sink which involved taking out and reinstalling the p-trap. When removing the p-trap I noticed the union nut was very tight. After my re-installation - hand tight - it leaked. Adding a bit of pipe dope and tightening a bit more with a wrench I heard some subtle creaking/(cracking?) and it's still leaking slowly. I'm assuming something may have cracked and I'm ok with replacing it if necessary, but some questions:

• How do I know if something cracked and needs replacing?
• Should I replace just the p-trap side of the drain with the union nut or cut away and replace the connector on the wall side as well?
• If replacing the connector on the wall side, what parts should I use and how should I do the install? I dislike the way that things are cemented since it means cutting a little more pipe each time I need to do a replacement.

Answer 1

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.