Stainless Steel Pipe Nipples: Common Types and Where Each One Fits

A pipe nipple is a short pipe section used as a fitting between female threaded pipe connections. Stainless steel nipples are common because they provide strength, durability, and corrosion resistance in piping systems.

Most stainless pipe nipples use male pipe thread on one or both ends. The correct type depends on pipe size, temperature, pressure, removal needs, and whether the connection joins pipe to pipe, pipe to hose, or pipe to a welded component.

Barrel Pipe Nipples

A barrel nipple has tapered pipe threads on both ends and an unthreaded section in the middle. This is one of the most common nipple forms because it can connect two female threaded fittings while leaving enough body length to handle and remove the part.

Barrel nipples are often used where the assembly may need to be serviced later and where a simple threaded transition is enough.

Threaded-One-End Nipples

A threaded-one-end, or TOE, nipple has a thread on one end and a plain end on the other. Unlike threaded-both-end nipples, it is not normally used to join two threaded fittings together.

This style can be used where one end needs a threaded connection and the other end serves another function, such as a support leg or a plain pipe end for a specific assembly.

Close and Shoulder Nipples

A close nipple, also called a running nipple, has threads along nearly the full body. It lets two fittings sit very close together, with little nipple body exposed between them.

That compact layout can be useful, but it also makes removal harder. The part can be damaged if it is removed without the right tool. A shoulder nipple is longer than a close nipple and has a very short unthreaded section in the middle, but not enough room for a normal pipe wrench grip.

Hex Nipples and Reducing Nipples

A hex nipple has a hexagonal center section that can be gripped with a wrench. This gives better mechanical advantage during tightening and removal, so it is useful when the nipple may be installed, removed, or replaced more often.

A reducing nipple connects a larger female connection to a smaller one. It is used when the piping system changes size or where flow and pressure conditions require a transition between two different connection dimensions.

Hose and Weld Nipples

A hose nipple has a male threaded end on one side and a hose barb on the other. It is used when a pipe connection has to transition to tubing or hose.

A weld nipple has a male threaded end on one side and a plain pipe end on the other. The unthreaded end can be welded into the system, leaving the threaded end available for easier connection to a pipe or fitting.

Choosing the Correct Nipple

Pipe nipples look simple, but the differences affect assembly length, serviceability, flow transition, removal method, and sealing risk. Confirm thread type, size, material, pressure rating, temperature, and whether the connection needs wrench access, a hose barb, a weld end, or a reducing transition.