1-1/2 inch Black Iron Cap

1-1/2 inch Black Malleable Iron Cap – Threaded Fitting for System Termination

The 1-1/2 inch Black Malleable Iron Cap is a threaded pipe fitting used to seal the end of a male-threaded pipe in non-potable pressure systems. Designed to close off unused branches or temporarily terminate pipe runs, this fitting provides a durable closure solution in gas, steam, and oil piping networks.

Manufactured from ASTM A197 malleable iron and finished with a protective black oxide coating, this cap offers mechanical strength and moderate corrosion resistance. It is commonly specified in indoor systems where galvanization is not required, and welding or permanent closure is not appropriate.

Product Features

• ✅ Threaded Female NPT Connection: Designed for compatibility with standard male pipe threads (NPT), per ASME B1.20.1.
• ✅ Malleable Iron Construction: Offers tensile strength and shock resistance in low- to medium-pressure systems.
• ✅ Black Finish: Suitable for fuel gas, air, steam, and water systems not requiring corrosion-resistant coatings.
• ✅ Pressure-Rated: Typically rated for up to 150 psi at ambient temperature in accordance with ANSI/ASME B16.3.

Technical Specifications

• Nominal Size: 1-1/2 inch
• Connection Type: Female NPT
• Material: Malleable iron (ASTM A197)
• Finish: Black (non-galvanized)
• Conformance: ASME B16.3 and UL/FM listings (when specified)

Installation Guidelines

Apply thread sealant or PTFE tape to the male threads before threading the cap into place. Use an appropriate pipe wrench to tighten the fitting without over-torquing, which may result in thread damage or sealing failure. Verify system pressure and media compatibility prior to commissioning.

Application Scope

This cap is commonly used in gas piping installations, hydronic heating systems, compressed air networks, and general-purpose mechanical piping. It provides a temporary or permanent closure point in systems where future expansion, inspection, or modification may occur.

Material Note

Black malleable iron is preferred for fuel gas and oil applications due to its mechanical strength and thermal resistance. It is not recommended for use in potable water systems unless protected against corrosion and approved by local code.

The 1-1/2 inch Black Malleable Iron Cap offers a code-compliant and durable termination option for threaded pipe ends in commercial and residential mechanical piping systems.