Merit Brass K419-04 Pipe Locknut 1/4 in 304 Ss Fnpsl 150 Psi

Product Description

The MERIT BRASS K419-04 is a 1/4 inch pipe locknut machined from 304 stainless steel, designed to secure threaded pipe fittings in place and prevent loosening under vibration or pressure cycling. With a 150 psi pressure rating and a female national pipe straight locknut (FNPSL) end connection, it is suited for plumbing, instrumentation, and light industrial piping assemblies. At 21/32 inch in length and weighing just 0.04 pounds, it is a compact, corrosion-resistant hardware component installed by licensed plumbers and pipefitters during system assembly or retrofit work.

This locknut is appropriate for residential and light commercial piping systems where a secure, vibration-resistant threaded connection is required. The 304 stainless steel construction makes it a practical choice in wet or mildly corrosive environments, including potable water, process lines, and HVAC condensate or instrument tubing applications. It is sold individually and suits single-connection service work as well as new installation projects.

Key Features

• 304 stainless steel construction resists corrosion in wet and mildly corrosive service environments
• FNPSL end connection provides a straight-thread locknut interface for secure fitting retention
• 150 psi pressure rating suitable for light commercial and residential piping systems
• Compact 21/32 inch length fits tight installation spaces
• Lightweight at 0.04 pounds — minimal load added to the piping assembly

Compatibility

Designed as an OEM-style replacement or new-installation component for 1/4 inch FNPSL threaded pipe connections in residential and light commercial plumbing and instrumentation systems.

Installation Notes

Installation is typically performed by a licensed plumber or pipefitter in accordance with the International Plumbing Code (IPC) and applicable local codes. Shut off and depressurize the line before installing or removing any threaded fittings. Use appropriate pipe thread sealant or PTFE tape on straight threads as required by the connection design. Do not overtighten — hand-snug plus wrench turns per fitting manufacturer guidance is standard practice.