521‑402HN – 3/8″ Black Malleable Iron Cap

Secure End Cap for Black Pipe Systems

The 521‑402HN is a heavy-duty, 3/8″ female-threaded cap made from malleable black iron, designed to seal the end of a threaded steel pipe in gas, oil, air, and non-potable water systems. Built to ANSI/ASME standards, this cap ensures durability and leak-free performance in residential, commercial, and industrial applications.

Key Features

Durable Malleable Iron Construction – Provides superior strength and resistance to mechanical stress.
Precision NPT Threads – 3/8″ female NPT threads ensure a secure, leak-proof seal.
Corrosion-Resistant Black Finish – Protects against rust and maintains an industrial look.
High Pressure & Temperature Tolerance – Suitable for applications up to 300–500 psi and temperatures up to 350°F.

Specifications

Model: 521‑402HN
Size: 3/8″ female NPT
Material: Malleable iron with black oxide coating
Length: ~1.0″
Weight: ~0.10 lb
Pressure Rating: Up to 300–500 psi
Temperature Rating: Up to 350°F

Applications

Gas & Fuel Lines – Ideal for natural gas, LP gas, and oil systems.
Air & Steam Systems – Handles compressed air and low-pressure steam.
Industrial & Residential Piping – Perfect for HVAC, plumbing (non-potable), and mechanical systems.
DIY & Decorative Projects – Great for industrial-style furniture and shelving.

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Diameter 3/8 Inch

Brand LDR Malleables

Fitting Type Cap

Size 3/8 inch

Material Malleable Iron

Finish Black Oxide

Connection Type FIP (Female Threaded)

Pressure Class 150 lb

Pressure Rating 300 PSI

Thread Standard ANSI/ASME B1.20.1

Standards ASTM A153, ASME B16.3

Temperature Rating -20°F to 150°F

UPC Code 032888406742

Shelf Pack 10

Minimum Order Qty 1

521-402HN 3/8IN BLACK CAP

About this item

521‑402HN – 3/8″ Black Malleable Iron Cap

Secure End Cap for Black Pipe Systems

Key Features

Specifications

Applications

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