Bk Mueller 521-331HC Reducing Coupling 1/2 X 1/4 in

Product Description

The BK MUELLER 521-331HC is a black malleable iron reducing coupling designed for threaded pipe systems operating at up to 300 psi. It transitions from a 1/2-inch female iron pipe (FIP) thread to a 1/4-inch FIP thread, making it a standard fitting for gas distribution lines, compressed air systems, and general-purpose plumbing. The Class 150 rating and black finish are characteristic of fittings used in low-pressure gas and industrial fluid service. Licensed plumbers and pipefitters install this type of fitting during new construction, retrofit work, and repair service on threaded iron pipe systems.

This reducing coupling is suited for residential and light commercial applications where a threaded iron pipe run requires a reduction in line size. Typical install scenarios include gas supply branch lines, air compressor distribution manifolds, and black iron pipe assemblies in mechanical rooms. The FIP-by-FIP thread configuration allows direct makeup onto male-threaded pipe ends or nipples on both sides of the fitting without adapters.

Key Features

• Malleable iron construction rated for 300 psi liquid and gas pressure service
• Class 150 classification suitable for low-pressure gas and compressed air lines
• Female iron pipe (FIP) threads on both ends for straightforward threaded makeup
• Black finish standard for gas-service black iron pipe systems
• Reduces from 1/2 inch to 1/4 inch in a single compact fitting

Compatibility

Designed as an OEM-style replacement or new-installation fitting for Class 150 threaded malleable iron pipe systems using 1/2-inch and 1/4-inch FIP connections.

Installation Notes

Installation should be performed by a licensed plumber or pipefitter in accordance with applicable local codes and the International Fuel Gas Code (IFGC) or International Plumbing Code (IPC) as relevant to the service. Shut off and depressurize the pipe system completely before disassembling or installing any threaded fittings. Apply an approved thread sealant or PTFE tape rated for the intended service medium to all male threads before makeup. Do not use pipe wrenches on fittings in a way that distorts the body or cracks the casting.