In some cases, these two words can be used interchangeably. The main difference between the two can be clearly found in the dimensional tolerance and their type of application. Tubes mainly have structural and mechanical applications, and as a result, their outer diameter (OD) is important, and as a result, dimensional accuracy in production should be more focused on their outer diameter than the inner diameter.

While pipes are usually used to transport gases and liquids, and for this purpose, their transferable flow rate, which depends on the internal diameter (ID), is important. The cross-section of the pipes is circular and provides them with the ability to withstand internal pressure. Meanwhile, apart from the circular section, the tubes are also produced in square and rectangular sections.The classification of pipes is usually done by the nominal size of the pipes (NPS) along with the nominal diameter and their Schedule number. The schedule number can be the same for different pipe sizes, but their wall thickness will be different.

The tubes can usually be ordered by reporting the outer diameter and wall thickness.However, sometimes the outer diameter is used along with the inner diameter or the inner diameter is also used along with the thickness. In general, from a dimensional point of view, pipes cover a wider range than tubes.

Key points:

Pipes are mainly used for fluid transfer, while tubes generally have mechanical applications.Pipes can be identified by three characteristics: NPS, nominal diameter and schedule number, while in tubes, outer diameter and thickness are important.

Compilation: Engineering-Research and Development Unit