Midland Industries 65661 Cored Square Head Plug 4 in Mpt Iron

Product Description

The MIDLAND INDUSTRIES 65661 is a cored square head plug designed for use in threaded pipe systems requiring a reliable, pressure-rated closure. Manufactured from black malleable iron, this fitting connects via a 4-inch male pipe thread (MPT) and is rated to 150 psi, making it well suited for gas, air, water, and steam distribution lines operating within standard low-pressure service conditions. It conforms to ANSI B16.3 dimensional standards. The square head design allows easy installation and removal using a standard pipe wrench or adjustable wrench. Licensed plumbers, pipefitters, and HVAC technicians regularly use this fitting during pipe system assembly and maintenance.

This plug is used in residential and light commercial piping applications where a threaded pipe end must be capped or a cored port must be maintained for future access. It is appropriate for black iron pipe systems commonly found in gas distribution, compressed air lines, and hydronic heating systems. The 4-8 thread designation and malleable iron construction make it a standard choice for 150-pound class fittings in these service environments. Its temperature range of -20 to 350 degrees F covers most typical in-building mechanical system applications.

Key Features

• 4-inch MPT connection for direct threading onto standard pipe ends
• Malleable iron construction provides strength and resistance to impact compared to cast iron
• 150 psi pressure rating suitable for low-pressure gas, air, water, and steam service
• Conforms to ANSI B16.3 dimensional standards for consistent fitment
• Operating temperature range of -20 to 350 degrees F
• Square head design accommodates standard pipe wrenches for easy installation and removal

Compatibility

Designed as an OEM-style replacement or new-installation fitting for 4-inch 150-pound class black malleable iron threaded pipe systems conforming to ANSI B16.3.

Installation Notes

Installation should be performed by a licensed plumber or pipefitter in accordance with applicable local plumbing and mechanical codes, including IPC and IFGC requirements where natural gas service is involved. Shut off and depressurize the pipe system completely before installing or removing any threaded fitting. Apply a code-approved pipe thread sealant or PTFE tape to the male threads before assembly. Do not use this fitting in systems exceeding its rated pressure or temperature limits.