Merit Brass 618B-06 Hex Countersunk Pipe Plug 3/8 Inch

Product Description

The MERIT BRASS 618B-06 is a hex countersunk pipe plug designed to seal off threaded pipe openings in plumbing, industrial, and fluid-system applications. Manufactured from 316/316L stainless steel, this plug offers strong corrosion resistance in harsh or wet environments. It features a 3/8 inch MNPT threaded end connection and carries a pressure rating of 150 psi. At 13/32 inch in length and weighing 0.03 pounds, it is a compact, single-piece fitting suited for tight installations. Plumbers, pipefitters, and mechanical contractors install this type of plug when blanking off unused pipe branches or completing pressure-tested assemblies.

This hex countersunk plug is used in residential and commercial piping systems where a low-profile, flush-style closure is needed on a 3/8 inch threaded port. The countersunk hex drive allows installation in recessed or confined spaces where a standard square-head plug would not clear surrounding components. The 316/316L stainless steel construction makes it suitable for applications involving water, mild chemicals, or corrosive media where carbon steel fittings would be inappropriate.

Key Features

• 316/316L stainless steel construction for excellent corrosion resistance
• 3/8 inch MNPT threaded connection for standard NPT pipe systems
• 150 psi pressure rating suitable for low-pressure plumbing and instrumentation lines
• Countersunk hex drive allows use in recessed or space-restricted port locations
• Compact 13/32 inch length minimizes protrusion in tight assemblies
• Lightweight at 0.03 pounds — easy to handle and stock in quantity

Compatibility

Designed as an OEM-style replacement or new-installation fitting for 3/8 inch NPT threaded pipe systems requiring a hex countersunk plug closure.

Installation Notes

Installation is performed by licensed plumbers or qualified pipefitters. Always depressurize and drain the system before removing or installing any threaded pipe fitting. Apply an appropriate thread sealant or PTFE tape to the MNPT threads before installation and tighten to snug plus a controlled number of turns — do not overtighten stainless steel threads, as galling can occur. Verify system pressure does not exceed the 150 psi rating after returning the line to service.