Premium Black Malleable Iron Round Cap Fitting (ASME B16.3 and ASTM A197 Compliant)
Engineered specifically for heavy-duty natural gas, LP (liquid propane), and mechanical piping networks, our Premium Black Malleable Iron Round Caps provide a highly dependable solution for sealing and terminating the male end of an open pipe run. Manufactured from high-strength cupola malleable iron, these female threaded caps are built to safely enclose structural distribution lines, equipment headers, or unused branch circuits under constant system pressures and mechanical vibration.
Featuring precision-cut internal National Pipe Taper (NPT) threads, these caps ensure an exceptionally tight mechanical wedge fit when threaded over standard schedule 40 black steel pipes. Every fitting is factory pressure-tested to guarantee zero wall porosity, offering ultimate safety behind walls or within mechanical rooms.
Key Features and Benefits
Heavy-Duty Malleable Iron Construction: Cast from premium ASTM A197 cupola malleable iron, delivering excellent tensile strength and structural fatigue resistance. It will not crack or fracture under heavy pipe wrench installation torque.
Deep Female Thread Profile: Designed with deep internal threads that completely enclose and protect the male pipe threads from environmental damage, dirt, and external impacts while maintaining a secure, permanent seal.
Precision-Tapered Internal NPT Threads: CNC-machined to strict ASME B1.20.1 standards. The smooth, deep-cut internal threads allow thread sealants or tape to distribute uniformly, creating a gas-tight seal that completely eliminates bypass leaks.
Low-Profile Round Geometric Design: The smooth, rounded exterior profile minimizes space requirements in tight wall cavities, overhead joists, and compact manifold assemblies while allowing standard pipe wrenches to maintain a positive grip.
Naturally Finished Black Coating: Treated with a raw black oxide finish and a light factory oil coat to provide dependable storage protection against atmospheric humidity and oxidation before job-site installation.
Technical Specifications
Fitting Profile: Round End Cap / Threaded Internal Pipe Cap (Female NPT Connection)
Material Standard: ASTM A197 / A197M Cupola Malleable Iron Castings
Dimensional Standard: ASME B16.3 Class 150 Malleable Iron Threaded Fittings
Thread Specification: ANSI / ASME B1.20.1 National Pipe Taper Internal Threads
Pressure and Temperature Ratings: Rated for up to 300 PSI at 150 degrees Fahrenheit, or 150 PSI at 300 degrees Fahrenheit
Fluid Compatibility: Natural gas, liquid petroleum (LP) gas, compressed air, oils, and non-potable closed systems (Note: Not for use in domestic potable water lines due to rust risks).
Ideal Applications
Capping Off Open Gas Pipes and Manifold Ends During System Additions and Structural Pressure Testing
Terminating Unused Branch Lines or Abandoned Stub-Outs Behind Finished Building Framing
Sealing End Ports on Commercial Compressed Air Distribution Rails and Piping Networks
Isolating Specific Gas Plumbing Zones During Multi-Stage Renovation and Mechanical Repair Work
