1/4 inch Black Iron Union Female x Female

1/4” Black Iron Union – Threaded Fitting for Gas and Mechanical Systems

The 1/4” black iron union is a two-piece, threaded pipe fitting designed to join two sections of male-threaded pipe in gas, air, and low-pressure liquid systems. It provides a serviceable connection that can be disassembled and reassembled without disturbing adjacent piping, making it ideal for systems that require future access or maintenance. Manufactured from black malleable iron, this union is used primarily in environments where galvanization is not required or permitted.

Application Details

Engineered for use in natural gas, LP gas, and air distribution lines, the 1/4” union allows mechanical separation of line segments while maintaining a pressure-rated seal when installed properly. Its central seat design ensures positive alignment and tight engagement under torque.

Specifications

• Nominal Size: 1/4 inch NPT
• Connection Type: Female NPT x Female NPT
• Material: Black malleable iron conforming to ASTM A197
• Thread Standards: ANSI/ASME B1.20.1 NPT (tapered)
• Operating Pressure: Suitable for systems rated up to 150 psi (consult system requirements)
• Temperature Range: -20°F to 450°F (varies with system media and sealant used)

Installation Considerations

Apply PTFE thread tape or approved joint compound to both male-threaded ends prior to installation. Tighten with a pipe wrench to manufacturer-specified torque to prevent misalignment or thread distortion. The union should be centered properly to ensure the ground seat forms a pressure-tight seal.

Typical Uses

This black iron union is commonly installed in:

• Natural and LP gas distribution systems
• Compressed air lines
• Low-pressure hydronic heating loops
• General mechanical piping applications where service access is required

Material Note

Black iron fittings are not intended for potable water systems due to their uncoated surface. They are suitable for fuel gases and mechanical systems where corrosion protection is not a critical factor or is provided externally.