What Are NPT Fittings?

What’s NPT Thread?

NPT stands for National Pipe Thread, which is a standard for tapered threads used on threaded pipes and fittings. NPT fittings are commonly used in plumbing and piping systems for joining pipes and creating connections. It is an American standard defined under the AMSE B1.20.1. The taper of the NPT threads allows for a tight seal between the male and female components when tightened together, preventing leakage. These fittings are widely used in industries such as oil and gas, water supply, chemical processing, and more.

Below are some more details of NPT fittings:

Thread design:

NPT threads are tapered, meaning they become narrower along the length of the thread. This taper is 1 in 16 on diameter, which means the diameter of the threads decreases by 1/16 inch per inch of length. This taper creates a tight seal when the male and female threads are tightened together.

Types of NPT fittings:

-NPT Male, These fittings have external threads that taper towards the end.

-NPT Female, These fittings have internal threads that taper towards the opening.

Material:

NPT fittings are available in various materials to suit different applications, including brass, stainless steel, steel, aluminum, and plastics such as PVC and nylon. The choice of material depends on factors such as the fluid being transported, pressure, temperature, and compatibility with other materials in the system.

Sizes:

NPT fittings come in a range of sizes, typically measured in nominal pipe sizes (NPS) or nominal inside diameters (NID). Common sizes range from 1/8 inch to 4 inches or larger, but they can be found in smaller or larger sizes depending on the application.

Sealing:

While NPT fittings provide a reliable seal when properly installed, they may require the use of thread sealant or Teflon tape (PTFE tape) to ensure a leak-free connection. This is particularly important for applications involving liquids or gases under pressure.

Applications:

-Plumbing systems in residential, commercial, and industrial buildings.

-Hydraulic systems for machinery and equipment.

-Pneumatic systems for compressed air.

-Oil and gas pipelines.

-Chemical processing plants.

-Water treatment facilities.

Thread chart of NPT thread:

Advantages of using NPT fittings:

1. Simple installation: NPT fittings are relatively easy to install, requiring only basic tools such as wrenches or pipe wrenches for tightening. Their threaded design simplifies the connection process compared to other types of fittings that may require soldering or welding.
2. Versatility: NPT fittings can be used with a variety of pipe materials, including steel, brass, stainless steel, copper, and various plastics. This versatility allows for greater flexibility in designing and constructing piping systems to meet specific requirements.
3. Tapered thread design: The tapered thread design of NPT fittings enables them to create a tight seal when properly tightened, reducing the likelihood of leaks or failures in the system. This design feature also allows for easy disassembly and reassembly of connections when necessary.
4. Suitable for high pressure and temperature: NPT fittings are suitable for use in high-pressure and high-temperature applications, such as hydraulic systems, steam lines, and oil and gas pipelines. The tapered threads provide a secure seal even under challenging operating conditions.
5. Cost-effectiveness: NPT fittings are generally cost-effective compared to other types of fittings, such as compression fittings or flanged connections. This affordability makes them an attractive choice for budget-conscious projects without compromising on performance or reliability.

QC Hydraulics is a leading manufacturer of high-grade quality stainless steel hydraulic NPT fittings, shapes cover straight nipples, elbows, tees, caps and plugs, sizes available from 1/8” to 2”. Please contact our team to learn more details and get professional advise.