It seems that the recommended flow rate for superheated steam in the manual is too high
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It seems that the recommended flow rates for superheated steam in the design manual are on the high side. The Design Manual for Power Piping recommends a steam flow velocity of 25~40 m/s for DN100~200 ； It is higher in the \"Chemical Process Design Manual\", 40~60. In actual calculations, the pipe diameter is selected based on a value close to the minimum of 25 m/s, and then the pressure drop is calculated. At 1.5 MPa, at pressures of around 1,200 or 1,300, the pressure drop is nearly 40%, which does not meet the pressure requirements of the users. It was found that the higher the superheating temperature of the steam, the greater the calculated pressure drop. Therefore, for pipes with long lengths or those that require a lower pressure drop, the pipe diameter should be chosen to be larger ； Then increase the insulation thickness further.
Your point makes sense; indeed, the flow rate of superheated steam affects the pressure drop. For long-distance pipelines, it is recommended to increase the pipe diameter and insulation thickness appropriately to reduce pressure drop and meet user requirements. At the same time, the actual operating conditions can be taken into account during design, allowing for flexible adjustment of the flow rate range to achieve better system performance. .
The manual does not indicate whether it applies to all operating conditions, nor is it explained how this was determined; at a speed of 60 meters per second, considerable noise is generated.