1/4 inch Black Iron Cap

1/4" Black Malleable Iron Cap – Threaded Closure for Gas and Hydronic Systems

The 1/4" Black Iron Cap is designed to terminate the end of a male-threaded pipe in low- to medium-pressure piping systems. Constructed from ASTM A197 malleable iron and finished with a protective black oxide coating, this cap is suitable for use in natural gas, LP gas, and hydronic heating lines where corrosion resistance and mechanical strength are required.

The internal threads conform to ANSI B1.20.1 standards, ensuring compatibility with schedule 40 and schedule 80 steel piping. It is intended for use in non-potable water and fuel gas applications and is not approved for potable water systems.

Performance and Construction Features

• ✅ Material Grade: Made from malleable iron per ASTM A197 for enhanced tensile strength and durability.
• ✅ Threading Standard: Female NPT threading (tapered) meets ANSI B1.20.1 specifications for secure sealing in threaded systems.
• ✅ Protective Coating: Black finish provides oxidation resistance for use in interior, dry environments.
• ✅ System Compatibility: Commonly used in gas distribution, fire protection, and closed-loop hydronic systems.
• ✅ Pressure Rating: Typically rated to 150 PSI at ambient temperature for steam or gas service (verify based on system design).

Technical Specifications

• Size: 1/4 inch nominal pipe size
• End Connection: Female NPT (FPT)
• Material: Malleable iron with black finish
• Applicable Standards: ANSI B16.3, ASTM A197, ANSI B1.20.1
• Temperature Range: -20°F to 450°F (with suitable sealant)

Installation Considerations

Apply an appropriate thread sealant (such as PTFE tape or pipe dope rated for gas) when installing onto male pipe threads. Avoid over-tightening to prevent cracking of the fitting or distortion of the threads. The cap is typically used as a permanent or test termination in pre-commissioned systems and can be removed for future extension if required.

Application Examples

This type of cap is frequently used in black iron piping systems for terminating unused ports in gas manifolds, sealing off supply lines during pressure testing, or capping off sections during phased installation of mechanical systems.

Regulatory Note

Not suitable for use in potable water systems due to the presence of surface coatings and lack of NSF certification. Approved for use in HVAC, fuel gas, and general-purpose mechanical piping under applicable mechanical and fuel gas codes.