I recently renovated my kitchen in my Manahattan co-op. The kitchen sink was clogged and I was told that the problem is with the"nipple and the sink trap". Is this the responsibility of the contractor? Or is one part, the nipple' inside the walls the responsbility of building?

Thank you

We're going to hafta have more information then that. Was this work permitted and inspected? Was the sink moved? Were the walls opened up and pipes moved? After the work was done did the sink "gurgle" when drained? How long after the work was done did it clog up?
Asv a rule you're responsible for any clogs UNLESS you can show the workmanship was wrong, out of code or shoddy.
Back to you, Tom