If you have a National Pipe Thread (NPT) pipe and a National Standard Free-Fitting Straight Mechanical Pipe Thread (NPSM) pipe, it will be obvious that the two are different. A male NTP cannot fit into an NPSM pipe. Although the thread angles run at 60 degrees on both pipes, the NTP pipe tapers slightly whereas the NPSM pipe remains straight.
National Pipe Thread
National Pipe Thread (NPT) is an established proportion for screw threads on pipes. The threaded part of an NPT pipe tapers slightly, at a 1.7899-degree angle. The pipe's diameter decreases by 3/4 inches per foot of pipe length. National Pipe Thread pipes usually range from 1/8 inches to 2 inches in diameter. NPT pipes are not as useful as other kinds of pipe at wider diameters. The National Pipe Thread convention is sanctioned by the American National Standards Institute, a nongovernmental organization that establishes standards for American industry.
National Standard Free-Fitting Straight Mechanical Pipe Thread
The National Standard Free-Fitting Straight Mechanical Pipe Thread (NPSM) piping convention refers to pipe thread that is not tapered. NPSM pipe threads do not seal as effectively as NPT threads.
Both NPT pipes and NPSM pipes go by other names. NPT pipes are also known as male iron pipe, female iron pipe, iron pipe thread, female pipe thread and male pipe thread. NPSM is sometimes also known as NPS.
Threaded pipes such as NPT seal tightly and are used to move liquids and gases. NPSM is not typically used to transport water or gases without an O-ring. Instead, they are used as structural pipes unless a sealer like an O-ring or tape is applied.
- Photo Credit Jupiterimages/Photos.com/Getty Images
Difference Between Nurse Practitioner & Physician Assistant
Nurse practitioners and physician assistants are highly educated, licensed professionals who provide medical care. Both are authorized to make medical diagnoses, order...
Metric Pipe Thread Size Guide
Most of the world uses the metric system to measure pipe sizes. However, America, Liberia and Burma still use the Standard English...
Definition of NPT and FPT Thread
NPT, national pipe threads, and FPT, female pipe threads, are terms used regarding U.S. pipe standards for tapered threads. NPT are common...
What Is Schedule 160 Pipe?
Schedule 160 pipe is one of several standard pipe classifications. The American National Standards Institute, ANSI, grouped pipe into schedules in the...
What is the Difference Between Pipe Thread & Conduit Thread
Thread refers to an internal ridge, or helical structure, used to convert between rotational movement, or allow an external (male) thread, or...
Rc 1/8 Metric Pipe Tap Information
British standard pipe taper (BSPT) internal thread is called Rc by the International Organization for Standardization (ISO). Rc refers to an internal,...
Hose-to-pipe fittings, also called adapters, allow a plumber to connect the threads of a hose spigot or water hose to the threads...
How to Seal Threaded Plumbing Pipes
How to Seal Threaded Plumbing Pipes. There are two ways to seal plumbing pipes. The first way is to use Teflon tape....
How to Calculate Minor Diameter
The minor diameter is an engineering reference to the diameter of a screw without the threads, as opposed to the major diameter,...
How to Measure a Steel Pipe
When people first start measuring pipes, they may be confused. After all, pipe sizes range from 1/16 up to 4, but these...
How Are Pipe Fittings Sized?
The sizes of pipe fittings can be very confusing because the sizes do not refer to any of the physical dimensions of...
How to Find the Cross Sectional Area of a Pipe
The pipe's cross-sectional area has a number of applications in fluid dynamics, letting you calculate a pipe's flow rate or pressure drop....