Bk 521-201HN Malleable Black Iron Coupling 1/4 in

Product Description

The BK 521-201HN is a 1/4-inch malleable black iron coupling designed for joining threaded pipe sections in gas, air, and general-purpose piping systems. Manufactured to ANSI/ASTM A-197 standards for malleable iron, this fitting delivers consistent dimensional accuracy and reliable thread engagement. Threads conform to ANSI B1.20.1, and dimensional compliance meets ANSI/ASME B16.3, B16.14, and B16.39 standards. Each fitting is individually flag tagged and 100% inspected and quality tested before shipment. Plumbers, pipefitters, and HVAC technicians working on low-pressure pipe assemblies rely on this type of fitting for straightforward inline connections on black iron systems.

This coupling is suited for residential and light commercial applications where threaded malleable iron fittings are specified. Typical use cases include natural gas distribution piping, compressed air lines, and general-purpose black iron pipe assemblies. The 1/4-inch size fits standard 1/4-inch NPT threaded pipe. It is sold individually, making it practical for service calls and small repair jobs where a single fitting is needed.

Key Features

• Malleable black iron construction meets ANSI/ASTM A-197 material standard
• Threads conform to ANSI B1.20.1 for consistent NPT fit
• Dimensional compliance with ANSI/ASME B16.3, B16.14, and B16.39
• 100% inspected and quality tested at the factory
• Individually flag tagged for easy identification on the job
• 1/4-inch size sold as a single unit

Compatibility

Designed as an OEM-style replacement or new-installation fitting for standard 1/4-inch NPT threaded black iron pipe systems.

Installation Notes

Installation is typically performed by licensed plumbers or pipefitters working on threaded iron pipe systems. Shut off gas or air supply and verify zero pressure before disassembling any existing piping. Apply appropriate thread sealant or listed pipe tape to NPT threads per the system requirements and applicable code, including IFGC provisions for gas piping. Do not over-tighten malleable iron fittings, as the material can crack under excessive torque.

Technical Specifications

• Material: Malleable Black Iron
• Material Standard: ANSI/ASTM A-197
• Thread Standard: ANSI B1.20.1 (NPT)
• Dimensional Standards: ANSI/ASME B16.3, B16.14, B16.39
• Pipe Size: 1/4 inch
• Weight: 0.108 pounds
• Sold As: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-201HN