[Hernan Rizza]

B16.10 is a valve specification, nothing to do here. On the other hand there is a lot of things that are not well defined in “the market”. If you want to see which is the correct way to order some product, you have to look in each specification, for example in A 312 (SS pipe) qty / name / process / grade / size, etc. That specification refers you to ASME B36.19 for pipe sch.

Check in ASME B36.10 which is the STANDARD FOR PRODUCT SIZES in SS pipe, near the end of the specification.