This is National Pipe Thread

National Pipe Thread (NPT) is an abbreviation for American National Standard Pipe Thread, also known as American National Standard Pipe Thread or American Pipe Thread. It is the U.S. technical standard for measuring threads of threaded pipe and fittings, as defined by ANSI/ASME Standard B1.20.1.NPT threads can be categorized into tapered and straight series depending on the application, but the tapered series is usually more common.

Characteristics of NPT threads:

Taper: The angle between the taper of NPT threads and the center axis of the pipe is approximately 1.7899°, or an approximate 1°47′24″.
Sealing: NPT threads, through their tapered design, are able to create a tight seal when connected, thus ensuring the safe transfer of fluids and gases.
Labeling: For male threads, NPT may also be referred to as MPT (Male Pipe Thread) or NPT(M); for female threads, it is referred to as FPT (Female Pipe Thread) or NPT(F).

Uses of NPT Threads:

NPT threads are widely used in the water and gas piping industry in North America, as well as in other industrial areas where pipe connections are required. Due to its good sealing and connection strength, NPT threads have become an integral part of piping projects.

Precautions for the use of NPT threads:

Material Selection: Under low pressure, iron or brass products can be used; while under high pressure, carbon steel and stainless steel products need to be selected to ensure the strength and safety of the connection.
Sizing: When using NPT threads, pipe size can be determined by measuring the thread diameter and subtracting ¼ inch.

This is National Pipe Straight Mechanical

National Pipe Straight Mechanical (NPSM for short) refers to U.S. straight pipe threads for mechanical connections. This standard is a pipe thread standard developed by the American National Standards Institute (ANSI) or the American Society of Mechanical Engineers (ASME) for use in the mechanical connection portion of a piping system.NPSM threads are characterized by their parallel, rather than tapered, thread design, which allows them to provide consistent mechanical tightness when connecting without relying on the taper of the threads to form a seal.

Application scenarios for NPSM threads:

NPSM threads are typically used for piping connections that require mechanical tightening rather than sealing. For example, NPSM threads can provide a reliable mechanical connection in piping systems where it is necessary to hold piping in position or to connect piping to other mechanical components.
NPSM threads are also commonly used in locknuts and other fasteners to ensure the stability and safety of piping systems.

Features of NPSM threads:

Parallel Thread: Unlike NPT (National Pipe Tapered Thread), NPSM utilizes a parallel thread design, which means that the diameter of the thread remains constant throughout its length.
Mechanical Tightness: The primary purpose of NPSM threads is to provide mechanical tightness, not sealing. Therefore, where sealing is required, it is often used in conjunction with other sealing elements such as gaskets.
Standardization: NPSM threads follow ANSI/ASME standards for dimensions and specifications, which allows for compatibility between pipes and fasteners produced by different manufacturers.

NPSM Thread Considerations:

When selecting and installing NPSM threads, it is necessary to ensure that the size, specification and material of the threads meet the design requirements to ensure a reliable and safe connection.
Because NPSM threads do not rely on the taper of the threads to form a seal, special attention needs to be paid to the selection and use of sealing elements where sealing is required.

What is the difference between National Pipe Thread and National Pipe Straight Mechanical?

National Pipe Thread (NPT) and National Pipe Straight Mechanical (NPSM) are two different pipe thread standards, and there are significant differences between them, mainly in the following areas:

Thread shape and application

NPT (National Pipe Thread): NPT is a tapered pipe thread standard with a tapered design. This design allows NPT threads to form a tight seal when connecting, and is particularly suitable for applications requiring a sealed connection, such as water pipes, gas pipes, etc. NPT threads are widely used in North America, including the United States, Canada, etc. NPT threads are widely used in North America, including the United States, Canada and other countries.

NPSM (National Pipe Straight Mechanical): NPSM, on the other hand, is a standard for straight pipe threads, which are parallel in design and do not have a taper. npsm threads are primarily used to provide a consistent mechanical fastening effect, rather than a seal. It is usually used for mechanical connections in piping systems, such as locknuts, to ensure the stability and safety of the piping system.

Sealing Performance

NPT: Due to its tapered design, NPT threads are able to automatically adjust and fit tightly to form an effective seal when connected. This sealing performance makes NPT threads particularly suitable for applications where fluid or gas leakage needs to be prevented.
NPSM: NPSM threads do not rely on the taper of the threads to form a seal, so their sealing performance is relatively weak. Where a seal is required, NPSM threads are often used in conjunction with other sealing elements, such as gaskets, to ensure a leak-tight connection.

Application Scenarios

NPT: NPT threads are widely used in piping systems that require sealed connections, such as plumbing, HVAC, air conditioning, refrigeration, etc., because of their good sealing performance.

NPSM: NPSM threads are more suitable for mechanical fastening rather than sealing, such as fixing, supporting and connecting piping systems.

Standardization and compatibility

Both follow the relevant standards set by the American National Standards Institute (ANSI) or the American Society of Mechanical Engineers (ASME), but the specifications and parameters are different.

Due to the differences in thread shapes and applications between NPT and NPSM, they are usually not used interchangeably. When designing and installing piping systems, it is necessary to select the appropriate thread standard for the specific application.

For more information about NPT and NPSM, please consult our engineers.