Description

The B K/MUELLER INDS(IMPORT) 521-705HN is a 1-inch black union fitting constructed from brass and iron. Unions allow piping systems to be disconnected and reconnected without cutting pipe or disturbing adjacent fittings, making them a standard component in gas, water, and mechanical piping installations. This fitting suits residential and light commercial applications where a serviceable mechanical joint is required on black iron pipe. Licensed plumbers and pipefitters install this type of union when equipment isolation and future serviceability are priorities on threaded pipe runs.

Black iron unions of this type are commonly found on natural gas and propane supply lines feeding furnaces, boilers, water heaters, and other gas-fired appliances. The 1-inch size fits standard Schedule 40 black iron pipe and is appropriate for new installations and retrofit work where existing piping must remain undisturbed during appliance servicing or replacement. This SKU is packaged in quantities of 5, making it suitable for stocking truck inventory or job-site supply needs.

Key Features

1-inch nominal pipe size fits standard Schedule 40 black iron pipe threads
Brass and iron construction provides durability on gas and water piping systems
Union design allows pipe disconnection without cutting or disturbing adjacent fittings
Packaged in quantities of 5 per package for efficient stocking and jobsite supply
Sold per each (EA) unit of measure for flexible ordering

Compatibility

Designed as an OEM-style replacement and standard fitment for 1-inch threaded black iron pipe systems used in gas, water, and mechanical piping applications.

Installation Notes

Black iron unions are installed by licensed plumbers or pipefitters following applicable codes such as the IFGC or IPC depending on the service medium. Always shut off gas supply or isolate water pressure and depressurize the line before disassembling or installing union fittings. Apply appropriate thread sealant rated for the service medium to all male threads before assembly. Do not over-tighten the union nut, as brass union seats can be damaged by excessive force.