Merit Brass K619-04 Pipe Locknut 1/4 in 316 Ss Threaded

Product Description

The MERIT BRASS K619-04 is a 1/4 inch pipe locknut machined from 316 stainless steel and designed for threaded piping assemblies. It uses a female national pipe straight locknut (FNPSL) end connection and carries a 150 psi pressure rating. At 15/16 inches in length, this locknut is sized for compact inline and panel-mount applications. Licensed plumbers, pipefitters, and mechanical contractors use this hardware to secure fittings, bushings, and bulkhead connections against panels or manifolds. The 316 stainless steel construction provides elevated corrosion resistance compared to 304 grade, making it suitable for wet, chemical, or marine-adjacent environments.

This locknut is well suited for light commercial and industrial plumbing systems where a low-pressure threaded connection point must be mechanically locked in place. Typical applications include instrument panel feedthroughs, fluid distribution manifolds, and process piping assemblies operating within the 150 psi working pressure limit. The FNPSL thread form accommodates straight-threaded male adapters without taper engagement, relying on a sealing face or gasket at the mating surface rather than thread interference.

Key Features

• 316 stainless steel construction for superior corrosion resistance in wet and chemical service environments
• FNPSL (female national pipe straight locknut) end connection for straight-thread panel-mount applications
• 150 psi pressure rating suitable for low-pressure fluid and instrumentation systems
• 15/16 inch body length in a compact 1/4 inch fitting size
• Threaded connection type with ISO standard compliance
• Sold individually — no minimum order beyond single unit

Compatibility

Designed as an OEM-style replacement or new-installation locknut for threaded 1/4 inch pipe fittings in low-pressure plumbing and instrumentation assemblies that require ISO-compliant straight-thread locknut hardware.

Installation Notes

Installation is performed by licensed plumbers or pipefitters following applicable IPC and facility piping codes. Shut off system pressure and verify a zero-pressure condition before removing or installing any threaded fitting hardware. Use an appropriate pipe wrench or open-end wrench sized to the locknut flats — do not use pliers or tools that can deform the seating face. Thread engagement and sealing method should follow the fitting manufacturer's specification for FNPSL connections, as straight threads do not self-seal on the thread form.