Sigma 812509610 Fig 3463 Ground Joint Pipe Union 3 in Fnpt

Product Description

The SIGMA 812509610 is a FIG 3463 ground joint pipe union rated for 150 lb service in malleable iron with a black oxide finish. Ground joint unions provide a metal-to-metal seat that resists leakage under pressure, making them a standard fitting in gas piping, steam systems, and industrial plumbing installations. The 3 inch nominal size and female NPT (FNPT) end connections on both the nut and tail piece allow straight-in thread engagement on standard pipe. Licensed plumbers and pipefitters install this fitting where a section of pipe must be periodically disconnected and reconnected without disturbing the rest of the run.

This union is suited for residential and commercial mechanical rooms, boiler rooms, and industrial process piping where malleable iron fittings are specified. The 150 lb pressure class aligns with standard black iron gas distribution and low-pressure steam piping applications. The black oxide surface treatment provides a uniform appearance consistent with other black iron system components and offers basic corrosion resistance in dry indoor environments. It is imported and conforms to the dimensional standards expected of FIG 3463 pattern ground joint unions.

Key Features

• 3 inch nominal size with FNPT end connections for standard pipe thread engagement
• 150 lb pressure class suitable for gas, steam, and low-pressure fluid service
• Ground joint metal-to-metal seat provides a reliable, reusable seal
• Malleable iron construction handles mechanical stress and thermal cycling common in piping systems
• Black oxide finish matches standard black iron piping assemblies

Compatibility

Designed as an OEM-style replacement and standard-service fitting for 3 inch malleable iron black iron piping systems using NPT threaded connections at the 150 lb pressure class.

Installation Notes

Installation should be performed by a licensed plumber or pipefitter in accordance with applicable plumbing and mechanical codes, including the IPC and IFGC where gas service is involved. Shut off and depressurize the system completely before removing or installing any union fitting. Apply appropriate thread sealant rated for the service medium to all NPT connections. Do not overtighten the union nut, as the ground joint seat requires only firm hand-plus-wrench engagement to seal properly.

Technical Specifications

• Nominal Size: 3 inches
• End Style: FNPT (Female National Pipe Thread)
• Pressure Rating: 150 lb
• Material: Malleable Iron
• Finish: Black Oxide
• Figure Number: FIG 3463
• Pattern: Ground Joint

Standard Information

• Brand: SIGMA
• Manufacturer Part Number: 812509610