Key Considerations for Selecting Pipe Nipples in Industrial Applications

Imagine facing a complex piping system where you need to connect pipes of different sizes and materials, struggling to find the right coupling solution. This guide explores eleven fundamental types of pipe nipples that will help you overcome various piping challenges while ensuring safe and efficient system operation.

Pipe nipples, also called pipe couplings or short pipes, are connecting components featuring external threads (MPT) at both ends. These threaded connections join with internal-threaded fittings, valves, or equipment to create watertight or airtight seals. Standard nipples typically don't exceed 12 inches in length—longer threaded pipes are classified as "cut lengths," which follow the same threading standards but with more lenient length tolerances.

The standard pipe nipple, often called a "barrel nipple," features tapered NPT threads at both ends with a smooth, unthreaded midsection. This design ensures reliable sealing while allowing wrench access during installation. When both ends are threaded, they're designated as "T.B.E." (Threaded Both Ends). Note that the specified length includes the threaded portions.

The T.O.E. (Threaded One End) nipple has threading on only one end, leaving the opposite end as plain pipe. Commonly used as tank support legs, these should not be confused with weld nipples—true weld nipples feature specially beveled ends for butt welding.

Weld nipples eliminate threading entirely, connecting via welding instead. This method proves superior in extreme conditions involving vibration, pressure surges, or temperature fluctuations. Without threaded sections weakening the pipe wall, weld nipples maintain greater structural integrity.

Close nipples contain no unthreaded areas—when two female-threaded components screw onto opposite ends, the nipple becomes virtually invisible. These are specified by diameter followed by "close" (e.g., "1/2" x close").

Slightly longer than close nipples, shoulder nipples feature a minimal unthreaded section between threads—too small for wrench engagement. When installed, a small portion remains visible between connected components, representing the first standard length increment above close nipples.

Named for their central hexagonal section, hex nipples allow secure wrench gripping during installation. When featuring different thread sizes at each end, they become reducing nipples for connecting dissimilar pipe diameters.

These specialized nipples combine right-hand threads on one end with left-hand threads on the opposite end. Frequently used in gas piping or applications prohibiting union joints, they also facilitate connections to female-threaded components in tight spaces where unions won't fit.

Swage nipples transition between different pipe sizes, available with plain, beveled, or threaded ends. They come in two configurations:

• Concentric: Primarily for vertical piping
• Eccentric: Designed for horizontal runs, installable either top-flat (preventing air pockets in pump suction lines) or bottom-flat (allowing condensate drainage in gas pipelines)

Manufactured without longitudinal welds, seamless nipples offer enhanced strength for high-pressure applications compared to their seamed counterparts.

Common in commercial/industrial buildings, mining, and process piping, grooved nipples come in three configurations (groove×groove, groove×bevel, groove×MPT) with sizes ranging from 1½" to 12". They're compatible with major grooved fitting systems like Shurjoint and Victaulic.

This highly versatile hose-to-thread adapter exclusively handles liquid media—never air or steam. While MPT ends are most common, variants include FPT, flanged, or plain-beveled welding ends. Note that combination nipples differ from male-threaded adapters designed specifically for polyethylene piping.

Understanding these nipple types will help you select the optimal solution for specific applications. While other specialized variants exist in the industry, these eleven represent the most common and practical options you'll encounter.