Bk 521-921BG Black Iron Hex Bushing 3/8 X 1/4 Inch

Product Description

The BK 521-921BG is a hexagon pipe bushing made from black malleable iron, used to reduce a 3/8 inch male NPT thread down to a 1/4 inch female NPT thread. This type of reducing bushing is a standard component in low-pressure gas piping, compressed air lines, and general plumbing distribution systems. The hex body allows wrench engagement for proper tightening without slipping. Each fitting ships individually flag tagged and carries the Mueller logo cast directly into the body. Material meets ANSI/ASTM A-197 and threads conform to ANSI B1.20.1 for reliable, leak-resistant connections.

This bushing is suited for residential and light commercial piping applications where a threaded iron reduction is needed between dissimilar pipe sizes. Typical install scenarios include gas appliance supply lines, air compressor fittings, and black iron piping manifolds. The hex profile seats into standard pipe fitting layouts and is interchangeable with other malleable iron fittings of the same thread specification. Sold individually.

Key Features

• Black malleable iron construction meets ANSI/ASTM A-197 material standard
• 3/8 inch male NPT x 1/4 inch female NPT reducing configuration
• Hex body design allows wrench engagement for secure installation
• Threads conform to ANSI B1.20.1 for consistent fit with standard NPT fittings
• Dimensions comply with ANSI/ASME B16.14 and B16.39
• 100 percent inspected and quality tested at the factory

Compatibility

Designed as an OEM-style replacement or standard addition for black iron threaded piping systems requiring a 3/8 inch to 1/4 inch NPT reduction.

Installation Notes

Installation is performed by licensed plumbers or gas fitters depending on the application and local code requirements. Shut off all gas or air supply and relieve system pressure before threading or unthreading any fitting. Apply an approved pipe thread sealant or PTFE tape to male threads before assembly. Do not overtighten malleable iron fittings, as the material can crack under excessive torque.

Technical Specifications

• Material: Black Malleable Iron
• Material Standard: ANSI/ASTM A-197
• Thread Standard: ANSI B1.20.1
• Dimension Standard: ANSI/ASME B16.14, B16.39
• Male Thread Size: 3/8 inch NPT
• Female Thread Size: 1/4 inch NPT
• Weight: 0.04 pounds
• Sold As: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-921BG