Bk 521-931HC Hex Black Iron Bushing 1/2x1/4

Product Description

The BK 521-931HC is a hexagon black iron pipe bushing used to reduce a 1/2-inch male NPT connection to a 1/4-inch female NPT connection. Constructed from black malleable iron meeting ANSI/ASTM A-197, this fitting is built for gas distribution, compressed air, and industrial piping systems where a threaded reduction is needed between two different pipe sizes. Threads conform to ANSI B1.20.1 for reliable seal engagement. Dimensions meet ANSI/ASME B16.14 and B16.39 standards. Licensed plumbers, pipefitters, and HVAC technicians install this fitting in both residential and light commercial applications. Each unit is individually flag tagged and 100% inspected at the factory before shipment.

This bushing is suited for black iron piping systems carrying natural gas, propane, compressed air, or steam in residential and commercial installations. The hex body allows wrench engagement during installation, making it practical in tight spaces where a standard reducing coupling would not fit. It is commonly found in gas appliance drops, air compressor manifolds, and boiler piping headers where a quick NPT size transition is required between a larger run pipe and a smaller branch or valve connection.

Key Features

• Black malleable iron construction per ANSI/ASTM A-197
• Hexagon body design allows wrench engagement for controlled torque
• Threads conform to ANSI B1.20.1 for standard NPT fitment
• Dimensions per ANSI/ASME B16.14 and B16.39
• Individually flag tagged and 100% factory inspected
• Mueller logo cast into body for manufacturer identification

Compatibility

Designed as an OEM-style threaded replacement fitting for black iron pipe systems using standard NPT connections. Fits any 1/2-inch male NPT outlet transitioning to a 1/4-inch female NPT port.

Installation Notes

Installation should be performed by a licensed plumber, pipefitter, or HVAC technician. Shut off gas supply or depressurize the piping system completely before removing any fittings. Apply an approved thread sealant or PTFE tape to the male threads before assembly and hand-tighten before using a wrench. All gas piping work must be performed in accordance with local codes and the International Fuel Gas Code (IFGC).

Technical Specifications

• Material: Black malleable iron, ANSI/ASTM A-197
• Male Thread Size: 1/2 inch NPT
• Female Thread Size: 1/4 inch NPT
• Thread Standard: ANSI B1.20.1
• Dimensional Standards: ANSI/ASME B16.14, B16.39
• Weight: 0.091 pounds
• Unit of Measure: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-931HC