Avoid writing only a nominal size on a pipe fitting inquiry. The supplier also needs the connection dimensions and wall-thickness requirement so the fitting can be checked against the mating pipe.
Use separate fields
Identify the nominal size designation used by the project, and state the actual pipe outside diameter when needed for matching. Keep wall thickness in its own field, using the specified schedule or a dimension with units. Schedule is a wall-thickness designation, not a working-pressure value.
Do not guess a dimension
ASME B36.10 addresses pipe dimensions. Use the applicable dimensional standard and edition to confirm values rather than treating every nominal designation as a measured diameter. For a reducer or reducing tee, list the sizes and wall requirements of each end separately.
Make exceptions visible
If the connected pipe uses a special wall, unusual bore or a different standard, attach the drawing and mark that requirement explicitly. Ask the supplier to identify any machining or dimensional exception in the quotation. The project engineer should confirm the final connection and service suitability.
Common question
Does the same schedule mean the same thickness for every pipe size? No. Supply the size and schedule together, or specify the confirmed thickness and relevant standard; do not transfer one thickness across an entire mixed-size list.