3/8 inch Black Iron Cap

3/8" Black Malleable Iron Cap – Threaded Pipe End Closure

The 3/8" Black Malleable Iron Cap is engineered to provide a reliable closure for threaded steel piping systems. Designed for use in low to medium pressure applications, this fitting is commonly employed to seal the end of a pipeline or fitting, maintaining system integrity and preventing contamination or leakage during maintenance or disconnection.

Manufactured from ASTM A197 malleable iron and finished with a protective black coating, this cap features tapered NPT threads conforming to ANSI/ASME B1.20.1 standards for compatibility with standard threaded pipe systems. Its structural strength and resistance to mechanical stress make it suitable for use in heating, air, gas, oil, and water distribution lines that do not involve potable water service.

Product Highlights

• ✅ Thread Type: NPT (National Pipe Tapered) for secure sealing on male-threaded ends
• ✅ Material: Malleable iron conforming to ASTM A197
• ✅ Finish: Black phosphate coating for moderate corrosion protection in dry environments
• ✅ Pressure Rating: Rated for up to 150 PSI (non-potable fluid systems)
• ✅ Application: Used to terminate pipe runs in gas, oil, air, and mechanical systems

Technical Specifications

• Nominal Size: 3/8 inch
• End Connection: Female NPT
• Manufacturing Standard: ASME B16.3
• Compliance: Meets MSS-SP-79, MSS-SP-83, and ASTM A197

Installation Notes

Threaded pipe caps should be installed using appropriate sealing materials such as PTFE tape or pipe joint compound to ensure a leak-tight connection. For systems subject to thermal cycling or vibration, proper torque application and inspection are recommended to prevent thread loosening. Do not use this product for potable water or corrosive media unless properly lined or coated per code.

Typical Applications

This 3/8" black malleable cap is routinely used in residential and commercial systems to terminate unused branches, facilitate pressure testing, or isolate sections of gas or oil piping. It is also applicable in fire protection systems, HVAC configurations, and low-pressure steam piping networks.

Industry Note

Black malleable fittings are valued for their strength and pressure-handling capabilities. They are generally preferred over cast iron components in mechanical systems due to their impact resistance and ability to be re-threaded or reused when properly maintained.

For durable pipe terminations that meet jobsite requirements and system specifications, specify the 3/8" Black Malleable Iron Cap for threaded closures in non-potable fluid or gas systems.