B K Mueller 521-801HN Black Pipe Plug 0.25 in 10 Pack

Product Description

The B K Mueller Industries 521-801HN is a black pipe plug used to seal open pipe ends in plumbing, HVAC, and gas piping systems. This plug fits a 0.25-inch pipe thread and is sold in a pack of 10 units, making it a practical choice for service vans and jobsite stock. Pipe plugs like this one are standard fittings used to pressure-test lines, cap unused ports, or permanently close off branch connections during rough-in or service work.

This plug is suited for residential and light commercial installations where a 0.25-inch threaded port needs to be sealed. Common applications include capping test ports on gas manifolds, closing unused taps on black iron distribution lines, and sealing off ports during pressure testing of plumbing systems. The black finish is typical of black iron pipe fittings used in gas distribution and low-pressure piping systems.

Key Features

• 0.25-inch pipe thread size for standard quarter-inch threaded ports
• Black finish consistent with black iron gas piping systems
• Sold in a pack of 10 units for jobsite and truck stock use
• Compact plug design for sealing unused pipe openings or pressure-test ports

Compatibility

Designed as an OEM-style replacement fitting for standard 0.25-inch threaded pipe applications in plumbing and gas piping systems.

Installation Notes

Installation is typically performed by a licensed plumber or HVAC technician. Before installing or removing any pipe plug on a gas or pressurized line, shut off the supply at the source and verify the line is depressurized. Apply appropriate thread sealant or PTFE tape to male threads per local code requirements. Follow applicable IFGC or IPC guidelines for the specific piping system being serviced.