Nipple (plumbing)

In plumbing

Plumbing

Plumbing is the skilled trade of working with pipes, tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters...

 and piping

Piping

Within industry, piping is a system of pipes used to convey fluids from one location to another. The engineering discipline of piping design studies the efficient transport of fluid....

, a nipple is a fitting, consisting of a short piece of
pipe

Pipe (material)

A pipe is round tubular section or hollow cylinder used mainly to convey media. It can also be used for structural applications. In layman's terms the appelations pipe and tube are almost interchangeable, but in industry and engineering discipline the terms are uniquely defined...

, usually provided with a male

Gender of connectors and fasteners

In electrical and mechanical trades and manufacturing, each of a pair of mating connectors or fasteners is conventionally assigned the designation male or female. The "female" connector is generally a receptacle that connects to and holds the "male" connector...

 pipe thread

National pipe thread

National Pipe Thread Tapered Thread is a U.S. standard for tapered threads used to join pipes and fittings. ANSI/ASME standard B1.20.1 covers threads of 60-degree form with flat crests and roots in sizes from ¹/₁₆ inch to 24 inch Nominal Pipe Size [NPS]...

 at each end, for connecting two other fittings.

The length of the nipple is usually specified by the overall length with threads. It may have a hex section in the center for wrench to grasp. A "close nipple" has no unthreaded area; when screwed tightly between two female fittings, very little of the nipple remains exposed.

In plumbing

Plumbing

Plumbing is the skilled trade of working with pipes, tubing and plumbing fixtures for drinking water systems and the drainage of waste. A plumber is someone who installs or repairs piping systems, plumbing fixtures and equipment such as water heaters...

 and piping

Piping

Within industry, piping is a system of pipes used to convey fluids from one location to another. The engineering discipline of piping design studies the efficient transport of fluid....

, a nipple is a fitting, consisting of a short piece of
pipe

Pipe (material)

A pipe is round tubular section or hollow cylinder used mainly to convey media. It can also be used for structural applications. In layman's terms the appelations pipe and tube are almost interchangeable, but in industry and engineering discipline the terms are uniquely defined...

, usually provided with a male

Gender of connectors and fasteners

In electrical and mechanical trades and manufacturing, each of a pair of mating connectors or fasteners is conventionally assigned the designation male or female. The "female" connector is generally a receptacle that connects to and holds the "male" connector...

 pipe thread

National pipe thread

National Pipe Thread Tapered Thread is a U.S. standard for tapered threads used to join pipes and fittings. ANSI/ASME standard B1.20.1 covers threads of 60-degree form with flat crests and roots in sizes from ¹/₁₆ inch to 24 inch Nominal Pipe Size [NPS]...

 at each end, for connecting two other fittings.

The length of the nipple is usually specified by the overall length with threads. It may have a hex section in the center for wrench to grasp. A "close nipple" has no unthreaded area; when screwed tightly between two female fittings, very little of the nipple remains exposed. A close nipple can only be unscrewed by gripping one threaded end with a pipe wrench

Pipe wrench

The pipe wrench, or Stillson wrench is an adjustable wrench used for turning soft iron pipes and fittings with a rounded surface. The design of the adjustable jaw allows it to rock in the frame, such that any forward pressure on the handle tends to pull the jaws tighter together. Teeth angled in...

 which will damage the threads and necessitate replacing the nipple, or by using a specialty tool known as a nipple wrench

Nipple wrench (plumbing)

In plumbing, a nipple wrench is often known as an inside pipe wrench.An eccentric toothed gear is mounted on a hexagonal shaft. The wrench is introduced inside the pipe . As the wrench is turned, the eccentric gear is forced to grip the inside of the pipe...

 (or known as an internal pipe wrench) which grips the inside of the pipe, leaving the threads undamaged. When the ends are of two different sizes it is called a reducer or unequal nipple.
A barrel nipple or a pipe nipple is one which is usually made from pipe and is threaded only at both ends.

Threads used on nipples are BSP

British standard pipe thread

The British Standard Pipe thread is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external with an internal thread.-Types:...

, BSPT

British standard pipe thread

The British Standard Pipe thread is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external with an internal thread.-Types:...

, NPT

National pipe thread

National Pipe Thread Tapered Thread is a U.S. standard for tapered threads used to join pipes and fittings. ANSI/ASME standard B1.20.1 covers threads of 60-degree form with flat crests and roots in sizes from ¹/₁₆ inch to 24 inch Nominal Pipe Size [NPS]...

, NPSM and rarely Metric.

Further reading

• ASTM A733-03 Standard Specification for Welded and Seamless Carbon Steel and Austenitic Stainless Steel Pipe Nipples.
• ASTM B687-99(2005)e1 Standard Specification for Brass, Copper, and Chromium-Plated Pipe Nipples.
• ASME B1.20.7 Hose Coupling Screw Threads, Inch. (Quote: The normal sequence of connections, in relation to the direction of flow, is from an externally threaded nipple into an internally threaded coupling)