Merit Brass K419-12 Pipe Locknut 3/4 in 304 Ss Fnpsl 150 Psi

Product Description

The MERIT BRASS K419-12 is a 3/4-inch pipe locknut designed for securing and locking threaded fittings in place within piping systems. Constructed from 304 stainless steel, it offers solid corrosion resistance in wet and moderately aggressive environments. The female National Pipe Straight Locknut (FNPSL) end connection provides a clean, vibration-resistant mechanical lock on standard NPT-threaded components. Rated to 150 psi and measuring 1-15/32 inches in length, this locknut is a reliable choice for plumbing and industrial installations where a secure, non-loosening connection is required. Plumbers and pipefitters are the typical installers for this type of fitting.

This locknut is suited for residential and light commercial plumbing, process piping, and mechanical system applications where 3/4-inch threaded pipe connections need to be locked against rotation or backed off under vibration or pressure cycling. The 304 stainless steel construction makes it appropriate for water supply, HVAC condensate, and general-purpose piping where mild corrosion resistance is needed. It is sold individually and is appropriate for new installation as well as maintenance and repair work.

Key Features

• 3/4-inch fitting size for standard NPT threaded pipe connections
• 304 stainless steel construction for corrosion resistance in wet service environments
• FNPSL end connection locks onto threaded fittings to prevent loosening
• 150 psi pressure rating suitable for general plumbing and mechanical applications
• Compact 1-15/32 inch length fits tight installation spaces
• Lightweight at 0.13 pounds for easy handling during installation

Compatibility

Designed as an OEM-style replacement or new-install component for 3/4-inch NPT threaded pipe systems in residential and light commercial plumbing and mechanical applications.

Installation Notes

Installation is typically performed by a licensed plumber or pipefitter following applicable IPC or local plumbing code requirements. Shut off system pressure and drain the line before installing or removing any threaded fitting. Use appropriate pipe wrenches or open-end wrenches sized for the locknut flats to achieve a secure engagement without over-torquing the stainless steel threads. Avoid mixing dissimilar metals in the connection assembly to prevent galvanic corrosion over time.