Bk 521-408BG Malleable Black Iron Pipe Cap 2 in

Product Description

The BK 521-408BG is a 2-inch malleable black iron pipe cap designed for threaded pipe systems in gas, plumbing, and mechanical applications. This fitting threads onto the end of an open pipe to seal it off, preventing flow, containing pressure, or capping unused branch outlets. Constructed from malleable black iron meeting ANSI/ASTM A-197 material standards, it is built for durability in low-to-medium pressure systems. Each fitting is individually flag tagged and 100% inspected before leaving the factory. Threads conform to ANSI B1.20.1 for consistent, leak-free engagement with standard NPT fittings. Licensed plumbers, pipefitters, and HVAC mechanics are the typical installers.

This cap is suited for residential and light commercial piping installations where a threaded black iron end closure is needed. Common applications include natural gas distribution systems, fuel oil lines, and general mechanical piping where black iron fittings are specified. The 2-inch size fits standard 2-inch NPT threaded pipe ends. It is sold individually and is appropriate for both new construction and retrofit work where an open pipe end requires a permanent or temporary seal.

Key Features

• Malleable black iron construction meets ANSI/ASTM A-197 material specification
• Threaded to ANSI B1.20.1 for standard NPT compatibility
• Dimensions conform to ANSI/ASME B16.14 and B16.39 standards
• 100% inspected and quality tested at the factory
• Individually flag tagged for easy identification at the job site
• Mueller logo cast into the body of each fitting

Compatibility

Designed as an OEM-style replacement and standard fitting for 2-inch NPT threaded black iron pipe systems in gas, plumbing, and mechanical piping applications.

Installation Notes

Installation is performed by licensed plumbers or pipefitters following applicable local codes and IFGC requirements where gas systems are involved. Shut off and depressurize the pipe system before threading on the cap. Apply an approved pipe thread sealant or PTFE tape rated for the service medium prior to making up the joint. Do not over-tighten; use a pipe wrench sized appropriately for the fitting to avoid cracking the casting.

Technical Specifications

• Size: 2 inches
• Material: Malleable black iron
• Material Standard: ANSI/ASTM A-197
• Dimension Standard: ANSI/ASME B16.14, B16.39
• Thread Standard: ANSI B1.20.1
• Weight: 0.934 pounds
• Unit of Measure: Each

Standard Information

• Brand: BK
• Manufacturer Part Number: 521-408BG