B K Mueller 521-704HN 3/4 Inch Black Union Fitting

Product Description

The B K Mueller Industries 521-704HN is a 3/4 inch black union fitting constructed from brass and iron. Unions allow a section of pipe to be disconnected and reconnected without rotating the pipe itself, making them essential for service and repair work on threaded black iron piping systems. This fitting is sized for 3/4 inch pipe and is suited for low-pressure gas and mechanical piping applications commonly found in residential and light commercial installations. Licensed plumbers and gas fitters install this type of union when service access to downstream components must be maintained over the life of the system.

This union is intended for use on threaded black iron pipe systems. Typical applications include natural gas supply lines, propane distribution piping, and other low-pressure mechanical piping where periodic disconnection is required. The 3/4 inch size fits standard Schedule 40 black iron pipe of the same nominal diameter. It is available in a package quantity of 15 units, making it practical for contractors stocking for multiple jobs or service calls.

Key Features

• 3/4 inch nominal pipe size for direct replacement or new installation on standard black iron pipe runs
• Brass and iron construction for durability in threaded piping assemblies
• Union design allows pipe section removal without rotating adjacent pipe
• Black finish consistent with standard black iron pipe systems
• Sold in a package of 15 units

Compatibility

Designed as an OEM-style replacement or standard union fitting for 3/4 inch threaded black iron pipe systems in residential and light commercial gas and mechanical piping applications.

Installation Notes

Installation is performed by a licensed plumber or gas fitter in accordance with applicable local codes and the International Fuel Gas Code (IFGC) where gas service is involved. Shut off gas supply and confirm zero pressure before disassembling or installing any union on a gas line. Use appropriate thread sealant rated for gas service on all threaded connections. Do not overtighten the union nut, as this can damage the seating surface and cause leaks.