Bk Mueller 521-342HC Reducing Coupling 3/4 X 3/8 in Threaded

Product Description

The BK MUELLER 521-342HC is a black malleable iron reducing coupling designed for threaded pipe connections in gas and liquid distribution systems. It steps down from a 3/4-inch FIP connection to a 3/8-inch FIP connection, making it a standard fitting for branch reductions in black iron pipe systems. The Class 150 rating carries a 300 psi pressure rating, suitable for a wide range of low- and medium-pressure applications. Plumbers, pipefitters, and gas service technicians install this fitting when reducing pipe size at a junction without requiring a union or other transition hardware.

This reducing coupling is used in residential and light commercial black iron pipe systems, most commonly in natural gas and propane distribution lines, as well as in compressed air and general liquid service piping. It is appropriate wherever a straight inline reduction is needed between a 3/4-inch and 3/8-inch threaded line. The black finish is standard for gas service applications and provides corrosion resistance suited to dry or mildly humid environments.

Key Features

• Malleable iron construction provides durability and reliable thread engagement under pressure
• 300 psi pressure rating for gas and liquid service at Class 150
• 3/4 x 3/8 inch FIP threaded ends for inline size reduction without additional fittings
• Black finish standard for gas distribution piping
• Compact, single-piece reducing coupling eliminates need for bushings in many applications

Compatibility

Designed as an OEM-style replacement and standard trade fitting for black malleable iron threaded pipe systems using 3/4-inch and 3/8-inch FIP connections in Class 150 gas and liquid service.

Installation Notes

This fitting is installed by licensed plumbers or gas fitters in accordance with IFGC and applicable local codes. Shut off and depressurize the gas or fluid supply before beginning any pipe work. Apply an approved thread sealant or PTFE tape rated for the service medium before making up threaded connections. Do not over-tighten; follow standard trade practice for malleable iron thread engagement to avoid cracking the fitting.