What is Pipe Nipples?
What are Pipe Nipples?
Screwed fittings are manufactured with threads on the inside of the fitting, and socket-weld fittings have an internal socket that prevents fitting makeup assembly. To facilitate the assembly of screwed and socket-weld fittings, small lengths of pipe called pipe nipples are used between fittings.
What are Pipe Nipples?
- Pipe nipples can vary in length depending on the distance required to fabricate the pipe configuration.
Pipe Nipples - A close nipple provides the minimum length of pipe between fittings.
- Screwed and socket-weld fittings have a certain amount of lost pipe due to thread engagement and socket depth.
- Therefore, each size pipe has a different minimum length for the dimension of a close nipple.
- Many manufacturers will use 3″ as the standard minimum for pipe nipples.
- This length will accommodate the amount of pipe lost inside the fitting on each end as well as provide sufficient wrench clearance during assembly for the larger screwed and socket-weld pipe sizes.
- They are mentioned by their diameter and their overall length.
Pipe nipples are manufactured in various materials such as stainless steel, carbon steel, brass, PVC, and alloys, and they come in a range of pressure ratings and lengths (referred to as close, short, long, extra-long, etc.).
Selection Criteria of Pipe Nipples
Common Materials
- Carbon Steel – General industrial use, suitable for oil, gas, and steam. Stainless Steel (304/316)
- Corrosion-resistant; used in food, pharma, and chemical industries.
- Brass – Good for water and air applications.
- PVC or CPVC – Lightweight and corrosion-resistant; used in water distribution and chemical handling.
Size and Schedule (Wall Thickness)
- Why it matters: Correct Nominal Pipe Size (NPS) and Schedule (SCH) ensure the nipple matches the connected piping system and can handle internal pressure.
- NPS: Nominal bore (e.g., 1/2″, 1″, 2″) Schedule: SCH 40, 80, 160, etc., indicating wall thickness.
End Connection Type
- Options: Threaded (Male NPT or BSPT) are common in temporary or modular systems.
- Plain/Beveled Ends are for welding.
- One Threaded & One Plain End is mainly used for valve connections or welding one side.
Pressure and Temperature Ratings
- The nipple should withstand the system’s maximum pressure and temperature.
- Forged Steel Nipples are used in Class 3000/6000 pressure ratings.
- Seamless Nipples are preferred for high-pressure and high-temperature systems.
How are pipe nipples used?
- Connection of Components Pipe nipples are often used to connect two pipe fittings or a pipe and a fitting.
- This is common in both permanent and temporary systems, making them valuable during both construction and repair operations.
- In a chemical processing plant, pipe nipples are used to connect check valves to horizontal pipelines carrying corrosive liquids.
- Extension of Piping
- When the existing piping system needs to be extended by a short length, a pipe nipple provides a quick and effective solution without requiring long pipe spools or complex fabrication.
- Pressure Tapping and Instrumentation
- In industries like oil and gas or power generation, pipe nipples are commonly used for pressure taps or mounting instruments like pressure gauges and flow meters.
- System Modifications and Repairs
- Pipe nipples facilitate fast replacement or modification of existing pipelines.
- They allow technicians to insert or remove valves, fittings, or sensors without disturbing the larger system.
- Use in High-Pressure and High-Temperature Systems
- Pipe nipples made from forged steel or stainless steel are extensively used in high-pressure steam, hydraulic, and chemical systems because of their strength and resistance to stress.
- Adaptation between Different Sizes or Threads
- Reducer or special-type nipples help connect pipes or fittings of different diameters or thread types.