Bk 521-404BG Malleable Black Iron Pipe Cap 3/4 in

Product Description

The BK 521-404BG is a 3/4-inch malleable black iron pipe cap used to terminate open pipe ends in gas, air, and general piping systems. Manufactured from black malleable iron meeting ANSI/ASTM A-197 material standards, it provides a durable, pressure-rated closure for threaded pipe ends. Each fitting is 100% inspected and quality tested before shipment. The Mueller logo is cast directly into the body of each fitting. This cap is sold individually and is a standard choice for plumbers, pipefitters, and HVAC technicians working with threaded black iron pipe assemblies.

This fitting is suited for residential and light commercial piping applications where a threaded black iron cap is required to plug or seal a pipe end. Typical uses include capping unused branch outlets, sealing test ports, and closing off temporary or permanent pipe terminations on gas lines, compressed air systems, and other compatible black iron pipe installations. The fitting ships individually flag tagged for easy identification on the job.

Key Features

• Black malleable iron construction meets ANSI/ASTM A-197 material specification
• Dimensions conform to ANSI/ASME B16.3, B16.14, and B16.39 standards
• Threads cut to ANSI B1.20.1 for reliable NPT thread engagement
• 100% inspected and quality tested at the factory
• Mueller logo cast into the fitting body for brand traceability
• Individually flag tagged for easy identification on the job site

Compatibility

Designed as an OEM-style replacement fitting for 3/4-inch NPT threaded black iron pipe systems in residential and commercial plumbing, gas, and HVAC piping applications.

Installation Notes

Installation of black iron pipe fittings on gas systems should be performed by a licensed plumber or pipefitter in accordance with applicable local codes and IFGC requirements. Shut off and depressurize the pipe system before removing or installing any threaded fittings. Apply an approved pipe thread sealant or PTFE tape rated for the service medium to the male threads before assembly. Do not overtighten threaded connections, as malleable iron fittings can crack under excessive torque.

Technical Specifications

• Material: Malleable black iron, ANSI/ASTM A-197
• Pipe Size: 3/4 inch
• Thread Standard: ANSI B1.20.1 (NPT)
• Dimensional Standards: ANSI/ASME B16.3, B16.14, B16.39
• Weight: 0.2 pounds
• Unit of Measure: Each
• Minimum Order Quantity: 5
• UPC: 00032888406766

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-404BG