3/8 inch x Close Black Steel Nipple

3/8" x Close Black Steel Pipe Nipple – Threaded Schedule 40 Fitting

The 3/8" x Close black steel nipple is a short, fully threaded Schedule 40 fitting used for direct connection between two female-threaded pipe components. Manufactured from welded black steel pipe conforming to ASTM A53 standards, this fitting provides a compact, durable solution for non-potable systems requiring minimal spacing between connected elements.

Close nipples are defined by thread engagement across nearly the full body length, leaving little or no unthreaded shoulder. They are commonly used in industrial and mechanical piping systems where tight clearances and structural rigidity are required.

Key Technical Features

• ✅ Thread Type: NPT (National Pipe Tapered), ANSI B1.20.1 standard
• ✅ Material: Welded black steel, typically ASTM A53 Grade A or B
• ✅ Nominal Size: 3/8" diameter x close length (~1–1.5" overall, fully threaded)
• ✅ Pressure Rating: Dependent on system specifications; compatible with low- to medium-pressure air, water, and fuel gas applications
• ✅ Finish: Black oxide – suitable for indoor, dry environments where corrosion protection is not a primary concern

Installation Guidelines

To ensure a secure and leak-resistant joint, use PTFE tape or pipe thread sealant on male threads. Due to the minimal unthreaded surface, pipe wrenches should be applied to adjacent fittings rather than the nipple itself to prevent thread damage. Close nipples are not intended for systems requiring frequent disassembly or alignment-sensitive applications.

Typical Applications

This fitting is frequently used in compressed air systems, gas piping networks, boiler piping manifolds, and low-pressure fluid connections. Its compact profile makes it ideal for use in tight mechanical assemblies, control panel manifolds, and installations with limited pipe run space.

Material Insight

Black steel pipe and nipples are commonly used in systems that do not require internal corrosion resistance. They offer strong mechanical properties, dimensional consistency, and ease of welding or threading, making them standard in commercial and industrial environments where potable water use is not required.