What is a Pipe?
The term pipe covers a specific range of sizes laid down by ANSI specifications. Any sizes not covered by these specifications are tube.
Stainless Steel Pipe dimensions determined by ASME B36.19 covering the outside diameter and the Schedule wall thickness.
Note that stainless wall thicknesses to ANSI B36.19 all have an ‘S’ suffix. Sizes without an ‘S’ suffix are to ANSI B36.10 which is intended for carbon steel pipes.