Midland Industries 66766 Hex Socket Countersunk Plug 1 in Mnpt

Product Description

The MIDLAND INDUSTRIES 66766 is a hex socket countersunk plug designed to close off open pipe ends in threaded piping systems. It threads into a female NPT port using a 1-inch male NPT connection and a 1-11.5 thread form. A recessed hex socket drive allows installation in tight spaces where a standard external wrench cannot reach. Constructed from steel with a zinc-plated finish, the plug resists corrosion in typical indoor and light-duty piping environments. It carries a 150 lb pressure class rating and meets ASME B16.14-1991 dimensional standards, making it a code-compliant choice for pressure piping work.

This plug is used in residential and light commercial gas, water, and general-purpose piping systems wherever a threaded port needs to be capped or temporarily sealed. Common install scenarios include capping unused tee outlets, blanking off test ports, and sealing branch connections on distribution headers. Plumbers, pipefitters, and HVAC mechanics regularly specify this fitting when working with galvanized or black steel pipe assemblies. The zinc-plated finish adds a layer of protection during storage and in low-humidity service environments.

Key Features

• 1-inch MNPT connection for direct thread-in installation
• 1-11.5 thread form per ASME B16.14-1991 dimensional standard
• 5/8-inch internal hex socket drive for installation in confined spaces
• 150 lb pressure class rating for standard piping service
• Steel construction with zinc-plated finish for corrosion resistance
• Temperature range of -20 degrees F to 350 degrees F

Compatibility

Designed as an OEM-style replacement and standard-stock fitting for 1-inch female NPT ports in steel pipe systems conforming to 150 lb class pressure ratings.

Installation Notes

Installation is performed by licensed plumbers or pipefitters working under applicable IPC or IFGC codes. Shut off and depressurize the system completely before threading in or removing any plug. Apply thread sealant or PTFE tape appropriate to the service medium before installation. Do not overtighten; use a calibrated torque wrench or follow the fitting manufacturer guidance for socket-drive plugs in steel pipe.