In the ASTM B36.10M standard, pipe is defined as “a fluid transport carrier based on the nominal pipe diameter (NPS), which proves that pipe is mainly based on its fluid transport capacity and its compatibility with other piping systems. In ASTM A249, tube emphasizes “a structural hollow body with precise size control”. The definition clearly highlights the accuracy required for the application.
Measurement method
Pipe: marked with NPS, which is an expression of many standard sizes, making it easier to match and connect.
Tube: marked with outer diameter (OD) and wall thickness (Wall Thickness), marking specific size information.
Tolerance grade
Pipe: does not need to be particularly accurate, with a tolerance range of ±0.3mm.
Tube: requires very high accuracy, with a tolerance range of ±0.1mm.
