Bk 521-920BG Hex Black Iron Bushing 3/8 X 1/8 Inch Npt

Product Description

The BK 521-920BG is a hexagon black iron pipe bushing designed to reduce from a 3/8 inch male NPT connection to a 1/8 inch female NPT connection. Cast from black malleable iron to ANSI/ASTM A-197 material standards, this bushing handles the mechanical stress of threaded pipe assemblies in gas, air, and compatible fluid piping systems. Dimensions conform to ANSI/ASME B16.3, B16.14, and B16.39. Threads are cut to ANSI B1.20.1 for reliable engagement with standard NPT fittings. Each fitting is individually flag tagged and 100% inspected at the factory before shipment. The Mueller logo is cast directly into the body.

This bushing is used in residential and light commercial piping installations where a branch or outlet must step down from 3/8 inch to 1/8 inch pipe thread. Typical applications include gas distribution piping, compressed air systems, and general-purpose black iron piping assemblies. Plumbers, pipefitters, and HVAC technicians install this type of reducer bushing when connecting smaller-threaded valves, gauges, or fittings into a larger-threaded body. The hex profile allows wrench engagement for proper thread engagement without over-stressing the fitting.

Key Features

• Black malleable iron construction per ANSI/ASTM A-197
• 3/8 inch male NPT x 1/8 inch female NPT hex reducer bushing
• Threads cut to ANSI B1.20.1 for standard NPT compatibility
• Dimensions conform to ANSI/ASME B16.3, B16.14, and B16.39
• Hex outer profile for secure wrench engagement during installation
• Individually flag tagged and 100% inspected at factory

Compatibility

Designed as an OEM-style black iron reducer bushing for use in standard NPT threaded pipe systems. Suitable for use with other black malleable iron fittings meeting ANSI/ASME B16.3 dimensional standards.

Installation Notes

Installation is performed by licensed plumbers, pipefitters, or HVAC technicians depending on the service application. Apply an appropriate thread sealant or PTFE tape to the male threads before assembly. Hand-tighten first, then use a pipe wrench on the hex body to achieve proper engagement. For gas piping applications, verify all connections with an approved leak detection method before returning the system to service, per applicable local codes and IFGC requirements.

Technical Specifications

• Material: Black Malleable Iron (ANSI/ASTM A-197)
• Male Thread Size: 3/8 inch NPT
• Female Thread Size: 1/8 inch NPT
• Thread Standard: ANSI B1.20.1
• Dimensional Standard: ANSI/ASME B16.3, B16.14, B16.39
• Weight: 0.051 pounds
• Unit of Measure: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-920BG