Merit Brass X119-02 Brass Pipe Locknut 1/8 in Fnpt

Product Description

The MERIT BRASS X119-02 is a brass pipe locknut designed to secure fittings and bushings in threaded pipe assemblies. It features female NPT (FNPT) threads on both ends and carries a Class 125 pressure rating, making it suitable for low- to medium-pressure fluid and gas piping systems. Sized at 1/8 inch, this locknut is commonly used to lock threaded fittings in place against a panel, tank wall, or fixture surface. Licensed plumbers and pipefitters install this type of hardware in both new construction and service work. The part weighs 0.02 pounds and is sold individually.

This locknut is used in residential and light commercial plumbing, HVAC condensate and water supply lines, and instrumentation piping where a 1/8-inch FNPT threaded connection requires mechanical locking. It is appropriate for applications where a fitting must be held flush and secure against a mounting surface without rotation. Its brass construction provides corrosion resistance in water service and compatibility with standard copper and brass pipe systems.

Key Features

• 1/8-inch FNPT threaded connection for standard NPT pipe and fittings
• Class 125 pressure rating suitable for low- to medium-pressure systems
• Brass construction offers corrosion resistance in water and fluid service
• Compact locknut profile locks threaded fittings against panels and surfaces
• Weighs 0.02 pounds — minimal added load in tight installations

Compatibility

Designed as an OEM-style replacement and standard hardware component for 1/8-inch FNPT threaded pipe assemblies in plumbing and HVAC applications.

Installation Notes

Installation is typically performed by a licensed plumber or pipefitter following applicable IPC and local plumbing code requirements. Shut off the water or fluid supply and depressurize the line before working on any threaded connection. Use a properly sized wrench on the locknut flats — do not use pipe wrenches on the fitting body itself, as this can damage the threads. Apply thread sealant or PTFE tape to NPT threads in accordance with the fitting manufacturer's recommendations.