Nipple

What is a nipple?

A nipple is a short fitting with male threads on both ends. It is used to connect two female-threaded parts — for example, a valve to an elbow, or a pump outlet to a check valve. It is one of the most frequently needed parts in pump and booster pump installations, meter and filter connections, and in assembling manifolds and valve groups.

Nipple types

• Galvanized nipples: An economical and widely available option.
• Brass nipples: Corrosion-resistant; for drinking water and hot water lines.
• Reducing nipples: Male threads of different sizes on each end; for example, to connect a 1/2 inch fitting to a 3/8 inch fitting.
• Nipples in various lengths: For leaving a desired gap between components.

Reducing nipples provide a size transition without the need for a separate reducer fitting.

Selection and installation

The size of both ends of the nipple must match the female thread size of the parts being connected. Short nipples are preferred in tight spaces, while longer nipples are used where a gap between components is needed. During installation, PTFE tape should be wrapped in the direction of the thread turn, and the nipple should not be overtightened. Brass nipples are more durable in hot water lines and with corrosive water. The hexagonal body in the middle of the nipple makes it easy to grip with a wrench; gripping the threads to tighten will damage them.

Nipples in pump installation

Nipples are frequently used for transitions from the pump outlet to a five-way fitting, check valve, or valve. Checking the thread size on the pump port and selecting the correct nipple reduces unnecessary reducers and potential leak points. For vibrating connections, using a flexible hose instead of a nipple protects the installation.

Frequently asked questions

What is a reducing nipple?

It is a nipple with different sizes on each end; used for size transitions.

What is the difference between a nipple and a coupling?

A nipple has male threads; a coupling has female threads.

Where is a 3/8 inch nipple used?

It is commonly used in sink and cistern connections and in fixtures requiring a fine connection.

What should I do if the nipple is leaking?

Re-wrap with fresh PTFE tape and reconnect; if the thread is damaged, replace the nipple.

Can galvanized and brass nipples be mixed?

It is possible, but contact between dissimilar metals can lead to corrosion over time.

When is a long nipple needed?

A long nipple is used when sufficient space is needed between two components to work with a hand or wrench, or to bring a connection point forward in insulated pipes.