Bk 521-974BG Black Iron Hex Bushing 1-1/2 X 3/4 Inch

Product Description

The BK 521-974BG is a black malleable iron hex bushing used to reduce pipe thread sizes in gas, air, and general plumbing piping systems. It transitions from a 1-1/2 inch male NPT thread on the outer hex body to a 3/4 inch female NPT thread on the inner bore. The bushing is manufactured from malleable iron conforming to ANSI/ASTM A-197 and meets dimensional standards ANSI/ASME B16.3, B16.14, and B16.39. Threads comply with ANSI B1.20.1 for consistent fit with standard NPT fittings. Each piece is individually flag tagged and 100 percent inspected and quality tested before shipment.

This hex bushing is suited for residential and light commercial piping applications involving natural gas, propane, compressed air, or water service where a pipe size reduction is needed at a threaded connection. Plumbers, pipefitters, and HVAC technicians commonly use hex bushings when connecting gas appliances, pressure gauges, valves, or manifold assemblies to existing pipe runs. The hexagonal body profile allows standard open-end or adjustable wrenches to apply proper torque without damaging the fitting body.

Key Features

• Malleable iron construction meets ANSI/ASTM A-197 material specification
• 1-1/2 inch male NPT outer thread transitions to 3/4 inch female NPT inner thread
• Threads conform to ANSI B1.20.1 for reliable engagement with standard NPT fittings
• Dimensional compliance with ANSI/ASME B16.3, B16.14, and B16.39
• Hex body design accommodates standard hand tools for installation
• Individually flag tagged and 100 percent inspected and quality tested

Compatibility

Designed as an OEM-style replacement or new-installation fitting compatible with standard 1-1/2 inch to 3/4 inch NPT threaded piping systems in gas, air, and general plumbing service.

Installation Notes

Installation is typically performed by a licensed plumber or HVAC technician following applicable local codes and IFGC requirements for gas piping. Shut off and depressurize the affected line before removing or installing any threaded fitting. Apply appropriate thread sealant rated for the intended service medium before making up the joint. Do not use the fitting body as a lever point; use wrenches on the hex flats only to avoid cracking the casting.

Technical Specifications

• Material: Black malleable iron, ANSI/ASTM A-197
• Inlet Thread Size: 1-1/2 inches male NPT
• Outlet Thread Size: 3/4 inch female NPT
• Thread Standard: ANSI B1.20.1
• Dimensional Standard: ANSI/ASME B16.3, B16.14, B16.39
• Weight: 0.12 pounds
• Unit of Measure: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-974BG