Watts 821788 Lead Free Black Dielectric Union 1 Inch

Product Description

The WATTS 821788 is a 1-inch IPS lead free dielectric union designed to prevent galvanic corrosion and stray current damage in piping systems where dissimilar metals meet. The union separates two metal pipe sections using a Buna-N gasket that electrically isolates the tailpieces, stopping electrochemical degradation before it compromises the system. It connects female iron pipe thread to female iron pipe thread and includes a union nut and two tailpieces. Rated for service up to 180 degrees F at 250 psi, this fitting suits a range of demanding hot and cold water applications in both residential and commercial settings. Licensed plumbers install this fitting as part of routine system protection and code compliance.

This dielectric union is used across commercial and residential plumbing installations where copper, steel, or other dissimilar metal pipes join. Typical applications include hot water storage tanks, water heaters, air conditioning systems, processing tanks, steam piping, gas piping, and general water distribution lines. The black iron pipe thread connections make it a straightforward fit for steel or iron pipe systems requiring an isolation joint. It is especially common in boiler rooms, mechanical rooms, and utility spaces where mixed-metal piping is the norm.

Key Features

• Lead free construction meets drinking water compliance standards
• Buna-N gasket electrically isolates tailpieces to prevent galvanic and stray current corrosion
• Female iron pipe thread x female iron pipe thread (FIP x FIP) black connections
• Rated to 250 psi maximum working pressure
• Rated to 180 degrees F maximum operating temperature
• Includes union nut, two tailpieces, and gasket — complete assembly

Compatibility

Designed for use in residential and commercial plumbing systems connecting dissimilar metal pipes, including applications on hot water storage tanks, water and air conditioning systems, processing tanks, and steam, gas, and water piping. Suitable for 1-inch IPS FIP threaded connections.

Installation Notes

Installation is performed by a licensed plumber in accordance with local plumbing codes and the International Plumbing Code (IPC). Shut off the water supply and depressurize the system fully before disassembling any existing connections. Hand-tighten the union nut first, then use a pipe wrench to achieve a snug, leak-free fit — do not overtighten, as excessive force can damage the gasket and compromise the dielectric isolation. Inspect the Buna-N gasket for seating before pressurizing the system.

Technical Specifications

• Pipe Size: 1 inch IPS
• Connection Type: Female Iron Pipe Thread x Female Iron Pipe Thread (FIP x FIP)
• Maximum Working Pressure: 250 psi
• Maximum Operating Temperature: 180 degrees F (82 degrees C)
• Gasket Material: Buna-N
• Lead Free: Yes

Standard Information

• Brand: WATTS
• Manufacturer Part Number: 821788