Merit Brass K687-64 Pipe Union 4 in 316 Ss Fnpt 150 Psi

Product Description

The MERIT BRASS K687-64 is a 4-inch pipe union machined from 316 stainless steel and rated for 150 psi service. A union fitting allows a pipeline to be disconnected and reassembled without rotating pipe sections, making it a critical access point for maintenance and equipment removal in permanent piping systems. The 316 stainless alloy provides strong resistance to chlorides and corrosive media, making this fitting well suited for demanding fluid-handling environments. Both ends use female NPT (FNPT) connections, threading directly onto standard male NPT pipe ends. Licensed plumbers and pipefitters are the primary installers of this component.

This union is used in residential and commercial plumbing, industrial process piping, and chemical-handling systems where a break-apart joint is required. The 4-inch size serves larger main lines, pump suction and discharge connections, heat exchanger headers, and similar high-flow applications. The 316 stainless steel construction makes it appropriate for marine environments, food-processing facilities, and anywhere mild acids or chloride exposure is a concern. It is sold individually (package quantity of one).

Key Features

• 316 stainless steel construction resists corrosion in chloride-rich and chemically aggressive environments
• 150 psi pressure rating suitable for a wide range of commercial and industrial fluid systems
• FNPT x FNPT end connections thread onto standard male NPT pipe without additional adapters
• Union design allows full pipeline disassembly without rotating adjacent pipe sections
• 4-inch fitting size serves large-diameter main lines and equipment connections

Compatibility

Designed as an OEM-style threaded union for use in 4-inch NPT piping systems requiring 316 stainless steel construction and a 150 psi pressure rating.

Installation Notes

Installation should be performed by a licensed plumber or pipefitter in accordance with applicable plumbing codes such as the IPC. Depressurize and drain the system completely before removing or installing any union fitting. Apply an appropriate thread sealant or PTFE tape rated for the service fluid to all FNPT connections before assembly. Do not overtighten the union nut, as this can damage the sealing seat and cause leaks under pressure.