Bk Mueller 520-121HC 90 Reducing Elbow 3/8x1/4 Threaded

Product Description

The BK MUELLER 520-121HC is a 90-degree reducing elbow designed for threaded pipe installations in gas, air, and liquid distribution systems. Cast from malleable iron with a black finish, this fitting handles a 3/8-inch to 1/4-inch reduction while making a sharp directional change in the line. It uses female iron pipe (FIP) threads on both ends and carries a Class 150 pressure rating with a 300 psi working pressure, making it appropriate for low-to-medium pressure service. Licensed plumbers and pipefitters install this type of fitting when routing black iron pipe through tight spaces or when stepping down pipe diameter at a 90-degree turn.

This reducing elbow is suited for residential and light commercial applications where black iron pipe is required, including natural gas supply lines, propane distribution, compressed air systems, and general plumbing runs. The black finish is standard for gas piping in most jurisdictions. The 3/8-inch inlet by 1/4-inch outlet configuration is common at branch takeoffs and appliance connection points where flow is stepped down to a smaller diameter.

Key Features

• 90-degree reducing elbow changes direction and reduces pipe size in one fitting
• Malleable iron construction provides durability and resistance to mechanical stress
• Black finish meets standard requirements for gas piping applications
• FIP threaded connections on both ends for standard NPT pipe compatibility
• Class 150 rated at 300 psi working pressure for liquid and gas service
• 3/8-inch inlet by 1/4-inch outlet for common branch and appliance connections

Compatibility

Designed as an OEM-style replacement and standard-use fitting for black iron threaded pipe systems using NPT connections in gas, air, and liquid service applications.

Installation Notes

Installation should be performed by a licensed plumber or pipefitter in accordance with local codes and the International Fuel Gas Code (IFGC) or International Plumbing Code (IPC) where applicable. Shut off and depressurize the line completely before removing or installing any fittings. Apply an approved pipe thread sealant or PTFE tape rated for the service medium to all threaded connections. Do not over-tighten malleable iron fittings, as cracking can result.