Tubular Drain Parts

P-traps, tailpieces, waste arms, extension tubes, slip-joint elbows, trap offsets and the nuts and gaskets that hold them together.

Tubular is sized by outside diameter, which is why it does not interchange with pipe of the same nominal size. Lavatory work is 1-1/4", kitchen and laundry are 1-1/2", and a 1-1/2" trap will not thread onto a 1-1/4" tailpiece without a reducing washer.

Wall thickness decides how long the assembly lasts. Thin-wall chrome tube is meant for exposed work where appearance matters and nothing bumps it; 17-gauge brass survives a cabinet that gets used for storage. Plastic will outlast both underneath a disposer, where it never shows.

Two failures cause most callbacks on this material. A slip-joint washer installed with the bevel facing the wrong way will weep no matter how hard the nut is turned, and a trap arm run with too much fall will siphon the trap dry and let sewer gas into the room. The arm needs 1/4" per foot, no more.