3 inch Black Iron Cap

3 inch Black Malleable Iron Cap – Heavy-Duty End Seal for Piping Systems

The 3 inch Black Malleable Iron Cap is engineered to close off the end of threaded pipe in gas, oil, air, or steam systems where durable, pressure-rated sealing is required. Designed for use in conjunction with schedule 40 or 80 steel piping, this threaded cap delivers long-lasting performance in both commercial and industrial applications.

Manufactured from ASTM A197 malleable iron and finished with a protective black coating, this cap provides corrosion resistance suitable for indoor, non-potable applications. Its NPT (National Pipe Thread) tapered threads offer a secure, leak-resistant connection when paired with a compatible male-threaded fitting.

Key Product Features

• ✅ Material: ASTM A197 malleable iron for strength and ductility
• ✅ Threading: ANSI B1.20.1 NPT for standardized compatibility
• ✅ Finish: Black oxide coating for moderate corrosion resistance
• ✅ Pressure Rating: Rated for 150 psi at ambient temperature
• ✅ Application: Suitable for steam, air, natural gas, and oil systems

Installation Considerations

To ensure proper sealing, apply thread sealant or PTFE tape prior to tightening the cap onto a male-threaded pipe. Hand-tighten and finish with a pipe wrench to the manufacturer’s recommended torque. Avoid over-tightening, which can damage threads or compromise seal integrity.

Common Applications

This 3 inch black iron cap is widely used to terminate lines in mechanical systems, including:

• Natural gas distribution piping
• Compressed air systems
• Low-pressure steam systems
• Hydronic heating loops
• Oil and non-potable water service lines

Code and Material Notes

Black malleable iron fittings are typically used in applications where corrosion protection through galvanization is not required. For potable water or corrosive environments, alternate materials such as galvanized or brass may be necessary. Always verify local code requirements for material suitability.

Choose the 3 inch Black Malleable Iron Cap for pressure-rated end sealing where performance and mechanical integrity are critical. Its robust construction, code-compliant design, and dependable seal make it a trusted component for demanding fluid and gas control systems.