Are round tubing and pipe dimensioned the same?

Are round tubing and pipe dimensioned the same?

• A. Yes
• B. No; pipe is dimensioned by its nominal size and schedule while tubing is identified by the outside diameter and wall thickness
• C. Only in metric measurements
• D. They are not used in welding

Answer: (B)

Round tubing and pipe use different ways of describing their size, which is why they aren’t dimensioned the same. Pipe is sized by a nominal size (NPS) and a schedule, which together indicate the approximate bore and the wall thickness (and thus the pressure rating). Tubing, on the other hand, is described by its outside diameter and its wall thickness, giving a precise outside dimension and wall characteristic. Because these two systems specify dimensions in different ways, you can’t treat them as the same sizing scheme. That’s why the correct description is that pipe uses nominal size and schedule, while tubing uses outside diameter and wall thickness. This difference also explains why fittings and weldments are chosen based on the respective sizing conventions.

Round tubing and pipe use different ways of describing their size, which is why they aren’t dimensioned the same. Pipe is sized by a nominal size (NPS) and a schedule, which together indicate the approximate bore and the wall thickness (and thus the pressure rating). Tubing, on the other hand, is described by its outside diameter and its wall thickness, giving a precise outside dimension and wall characteristic. Because these two systems specify dimensions in different ways, you can’t treat them as the same sizing scheme. That’s why the correct description is that pipe uses nominal size and schedule, while tubing uses outside diameter and wall thickness. This difference also explains why fittings and weldments are chosen based on the respective sizing conventions.