Method: Saturated-steam specific volume is estimated from an embedded pressure-property table and interpolated at the entered absolute pressure. Steam volumetric flow is: V̇ = ṁ × v where: ṁ = steam mass flow rate v = saturated-steam specific volume Required flow area is: A = V̇ ÷ Velocity Required internal diameter is: D = √(4A / π) Pressure is converted internally to bar absolute. For gauge pressure, approximately 1.01325 bar atmospheric pressure is added. The reference DN/NPS result uses representative Schedule 40 internal diameters only to identify the next listed pipe with an internal diameter equal to or greater than the calculated requirement. Actual pipe internal diameter depends on nominal size, schedule, material and applicable piping standard. Final selection should therefore be checked using the actual pipe dimensions. This calculator sizes pipe from velocity only. Final steam-piping design should also check pressure drop, pipe length, fittings, steam quality, condensate drainage, erosion, noise, water hammer, allowable pressure and applicable piping codes. Superheated steam should use its actual specific volume rather than the saturated-steam values used by this calculator.