ASC Engineered Solutions 11/4X1 GALV MI 90 ELL

Yes. It is a reducing 90 degree elbow: one end is 1-1/4 inch, the other is 1 inch, so it turns the run 90 degrees and steps the pipe size down in the same fitting. That saves you from stacking a straight elbow and a separate bushing or reducing coupling at the turn.

Both ends are female pipe thread (FPT), so the elbow threads onto male-threaded pipe nipples or male adapters on each side. Threads are cut to ASME B1.20.1, the standard NPT taper thread, so it mates with any standard NPT pipe of the matching size. If you need a street-style elbow with one male end, this is not it.

Yes. Center-to-end dimensions are built to ASME B16.3, the malleable iron threaded fittings standard, so it drops into the same space as any other B16.3 1-1/4 x 1 reducing 90. Threads are NPT per ASME B1.20.1. If your existing fitting came off a B16.3 galvanized system, this replaces it without repiping.

The galvanized finish is applied to ASTM A-153, the hot-dip zinc coating spec for threaded hardware, which is what gives it corrosion resistance in wet, humid, or exposed locations. For buried or continuously submerged service, coat or wrap the joints as the job spec requires.

Mixing is not the usual practice. Galvanized malleable iron fittings like this 1-1/4 x 1 reducing 90 are normally run with galvanized pipe on water, sprinkler, and wet service; black malleable iron is what is typically used on fuel gas systems. Follow the material called out on your drawings and by the local code official rather than mixing finishes in one run.

Yes, use a thread sealant. The connections are tapered NPT female threads to ASME B1.20.1, and tapered pipe threads are sealed with a compatible pipe dope or PTFE tape rated for the service, not by metal-to-metal contact alone. On sprinkler work, use a sealant approved for fire protection service.