Bk 521-805BG Malleable Black Iron Pipe Plug 1 in

Product Description

The BK 521-805BG is a 1-inch malleable black iron pipe plug designed to seal off threaded pipe ends in plumbing, HVAC, and mechanical piping systems. The fitting is manufactured from black malleable iron meeting ANSI/ASTM A-197 material standards, with threads conforming to ANSI B1.20.1 for reliable, leak-free engagement. Dimensions comply with ANSI/ASME B16.14 and B16.39. Each fitting is individually flag tagged and 100% inspected and quality tested before leaving the factory. The Mueller logo is cast into the body of each fitting. At 0.2 pounds, this plug is a standard trade-grade component used by plumbers, pipefitters, and HVAC mechanics on threaded iron pipe assemblies.

This plug is suited for residential and light commercial applications where a threaded black iron pipe end requires capping during installation, testing, or system modification. Common install scenarios include capping unused branch outlets on gas lines, hydronic heating systems, and general-purpose iron pipe distribution systems. It is sold individually and is compatible with standard NPT threaded pipe and fittings at the 1-inch nominal pipe size.

Key Features

• Black malleable iron construction per ANSI/ASTM A-197
• Threads conform to ANSI B1.20.1 for standard NPT engagement
• Dimensional compliance with ANSI/ASME B16.14 and B16.39
• 100% inspected and quality tested at the factory
• Individually flag tagged for easy identification on the job
• Mueller logo cast into the body for manufacturer traceability

Compatibility

Designed as a standard NPT threaded replacement or new-installation pipe plug for 1-inch black iron pipe systems in plumbing, gas, and HVAC hydronic applications.

Installation Notes

Installation is typically performed by a licensed plumber or pipefitter. Shut off and depressurize the pipe system fully before removing or installing any threaded fittings. Apply an appropriate thread sealant or PTFE tape to the male threads before installation. On gas systems, verify all connections with a leak detection solution after pressurizing and follow applicable codes including the IFGC.

Technical Specifications

• Material: Malleable Black Iron
• Material Standard: ANSI/ASTM A-197
• Thread Standard: ANSI B1.20.1
• Dimensional Standard: ANSI/ASME B16.14, B16.39
• Pipe Size: 1 inch
• Weight: 0.2 pounds
• Unit of Measure: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-805BG