You have probably heard the terms pipe and tube used interchangeably, what the difference is between them. 

Tubing

Tubing is generally used for structural purposes and the OD is an important and exact number. Tubing size is specified by OD and the wall thickness (WT); and the measured OD and stated OD are generally within very close tolerances of each other. Tubing is usually more expensive than pipe due to tighter manufacturing tolerances.

Pipe

Pipes are categorized as tubular vessels used in pipeline and piping systems, and commonly transport gases or fluids. They are specified by “Nominal Pipe Size” (NPS) and Schedule (wall thickness). NPS is a size standard established by the American National Standards Institute (ANSI)

While determining the actual size, tubes and pipes are measured differently.

A tube is measured with the help of exact outside diameter (OD) with a set range of wall thickness. The wall thickness is vital as the tube’s strength is dependent on it.

On the other hand, we measure a pipe by using a nominal outside diameter. The most important property is the capacity or the inside dimension (ID).

Pipes accommodate larger applications with sizes that range from a half-inch to several feet. Tubes are generally used in applications that require smaller diameters. While a 10-inch pipe is common, it is rare that you will find a 10-inch tube.