Bk Mueller 521-806HN 1-1/4 in Threaded Square Plug Class 150

Product Description

The BK MUELLER 521-806HN is a 1-1/4 inch threaded square plug constructed from malleable iron with a black finish. It is rated Class 150 with a liquid and gas pressure rating of 300 psi, making it suitable for use in both piping and gas distribution systems. The square head design allows for positive wrench engagement during installation or removal. Licensed plumbers and pipefitters install this type of fitting to cap off pipe ends, blank unused branch outlets, or isolate sections of a system during service or repair work.

This square plug is well suited for residential and light commercial piping applications involving gas lines, water distribution, and other fluid-handling systems. The threaded end connection follows standard NPT pipe thread sizing, allowing it to mate with standard 1-1/4 inch threaded fittings and pipe. The black finish is typical for gas service applications where galvanized fittings are not permitted.

Key Features

• 1-1/4 inch threaded connection for standard NPT pipe compatibility
• Malleable iron construction for strength and impact resistance under pressure
• Black finish suited for gas service piping applications
• Class 150 rating with 300 psi liquid and gas pressure rating
• Square head design provides positive grip for wrench installation and removal

Compatibility

Designed as an OEM-style replacement or direct-use fitting for 1-1/4 inch NPT threaded pipe systems in residential and commercial gas and fluid piping installations.

Installation Notes

Installation should be performed by a licensed plumber or pipefitter in accordance with applicable codes including the IPC and IFGC. Shut off gas or fluid supply and relieve system pressure before installing or removing any pipe plug. Apply appropriate thread sealant or PTFE tape to the male threads before hand-tightening and torquing to a firm, leak-free fit. Do not overtighten malleable iron fittings, as the material can crack under excessive force.