Sigma 813507928 Ground Joint Pipe Union 3/8 in Fnpt 150 Lb

Product Description

The SIGMA 813507928 is a FIG 3463 ground joint pipe union rated for 150 lb service in a 3/8 inch nominal size with female NPT (FNPT) end connections. Constructed from galvanized malleable iron, this union is built to handle the mechanical stress and repeated make-and-break cycles common in piping systems. The ground joint seat design provides a metal-to-metal seal that resists leakage under pressure and temperature fluctuations. Plumbers and pipefitters install this fitting when a removable, inline connection is required for future serviceability on threaded iron pipe systems.

This union is suited for use in low-pressure commercial and residential piping installations including gas distribution, steam, and water systems where FNPT threaded connections are specified. The galvanized finish provides corrosion resistance in exposed or moderately humid environments. Its 150 lb pressure class makes it appropriate for standard-duty applications following ASME B16.3 malleable iron fitting specifications. It is typically installed by licensed plumbers or pipefitters working on threaded black or galvanized iron pipe assemblies.

Key Features

• Ground joint metal-to-metal seat for reliable, leak-resistant sealing
• 3/8 inch nominal size with FNPT end connections on both sides
• 150 lb pressure class rating suitable for standard-duty piping service
• Galvanized malleable iron construction resists corrosion in exposed environments
• Allows inline disconnection and reconnection without disturbing adjacent pipe runs

Compatibility

Designed as an OEM-style replacement or new-installation fitting for 3/8 inch nominal threaded iron pipe systems using FNPT connections at the 150 lb pressure class.

Installation Notes

Installation should be performed by a licensed plumber or qualified pipefitter in accordance with applicable plumbing codes such as the IPC or local jurisdiction requirements. Shut off and depressurize the line completely before disassembling or installing any union fitting. Apply an appropriate thread sealant or PTFE tape to the FNPT threads before makeup. Do not over-tighten the union nut, as this can damage the ground joint seat and compromise the seal.

Technical Specifications

• Nominal Size: 3/8 inch
• End Style: FNPT (Female National Pipe Thread)
• Pressure Class: 150 lb
• Material: Malleable Iron
• Finish: Galvanized
• Figure Number: FIG 3463

Standard Information

• Brand: SIGMA
• Manufacturer Part Number: 813507928