ECN Forum Forums General Topics of the Trade General Discussion Area Threading 2 1/2" Gal pipe.

Ed,
Conduit and plumbing pipe both should have the same threads... 3/4" to the foot taper.
NPT - National Pipe Thread Taper ANSI/ASME B1.20.1

This is the thread that is specified in 344.28 and its FPN.

The real difference is that conduit couplings are straight thread and plumbing couplings are tapered.