B K Mueller 521-342HC 3/4x3/8 Black Reducing Coupling

Product Description

The B K Mueller Industries 521-342HC is a black reducing coupling designed to connect pipe sections of two different diameters in a single inline fitting. It transitions from a 3/4 inch female connection to a 3/8 inch female connection, making it a practical solution for reducing pipe size within a run without adding extra fittings. This type of black-finish coupling is commonly used in gas distribution piping and general plumbing applications. Licensed plumbers and pipefitters install this fitting as part of standard rough-in and service work. Each unit is sold individually, and the package quantity is 20 units per pack.

This coupling is suited for residential and light commercial piping systems where an inline diameter reduction is required. Typical applications include natural gas supply lines, propane distribution, and black iron pipe assemblies where a step-down from 3/4 inch to 3/8 inch is needed within a run. The black finish is consistent with standard black malleable or black pipe fittings used throughout gas piping systems.

Key Features

• Reduces pipe diameter from 3/4 inch to 3/8 inch in a single inline fitting
• Black finish compatible with standard black iron pipe assemblies
• Sold individually with a package quantity of 20 units per pack
• Compact coupling profile for tight piping runs
• Suitable for gas and general plumbing pipe systems

Compatibility

Designed as an OEM-style replacement or standard-stocking fitting for black iron pipe systems requiring a 3/4 inch to 3/8 inch inline reduction.

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) where applicable. Shut off the gas or water supply and depressurize the line before beginning work. Apply thread sealant rated for the intended service to all male threads before assembly. Do not overtighten threaded fittings, as this can crack or distort the fitting body.