Other Remarks

ISO5167 defines b as the d/D ratio (bore diameter to pipe ID ratio) at the flowing conditions, therefore in particular it means at the operating temperature. This is the way b is reported by the software.

The calculation first calculated D by applying the thermal expansion to the pipe nominal diameter for the normal operating temperature, then either b is applied or calculated and d, the diameter of the bore at operating temperature is calculated. Finally the thermal expansion of the plate is calculated to determine d0, the bore diameter at ambient conditions (assumed to be 18 °C).