Select steam pipe size

Sugar Steam pipe is in the process of being installed

Why is steam pipe size important?

Steam pipe size plays a role important role in the steam distribution system because it directly affects the efficiency and safety of the system. Choosing the appropriate pipe size will ensure:

  • Supplying the necessary steam flow for the equipment used.
  • Minimize pressure loss during steam transport.
  • Limit noise due to steam flow water.
  • Save costs system installation and operation.

For a given application, only there is a technically suitable pipe size. If pipe design calculations are not done correctly, steam pipes can be sized too small or too large – both of which have adverse effects as given below

What will happen if the steam pipe is too large?

The pipe size is too large and will have the following consequences:

  • The pipe Large pipes produce less pressure drop at the same flow rate than small pipes. Therefore, steam users will receive steam at the required pressure. There will be no risk of steam shortage and the availability of steam is reliable.
  • Large pipes also reduce noise associated with steam flow. However, large pipes will be more expensive than small pipes. In addition, its installation and insulation costs are also greater. Therefore, installing large pipes is not economically viable.
  • Large pipes have a larger surface area, so the heat transfer area increases. As a result, convection and radiation losses are more, pipe losses increase, and a larger amount of condensate is formed. More steam needs to be generated to compensate for this loss, thereby increasing steam costs.

Determining the correct size of the steam pipeline is therefore as part of pipe design calculations is very important to ensure pipe losses are as low as possible.

What happens if the pipe is too small?

Small pipe size selected instead of correct size will have the following consequences:

  • Small pipe causes a large pressure drop than large pipes for the same steam flow. Therefore, steam users receive steam at low pressures that may not match the process parameters.
  • Small pipes have a smaller flow capacity than large pipes. Therefore, it will not be able to supply steam to steam users at the required flow rate and will result in steam shortage. This in turn will affect the process parameters and reduce the production rate / product quality.
  • Due to too small tube size, steam velocity increases and causes pulsation water and corrosion. Damping has dangerous effects.

Therefore, proper pipe sizing for a given application is important. 

How is steam pipe size selection done?

There are two main methods to choose steam pipe size:

Velocity Method

This method is based on the assumption of the velocity of the steam and the calculation of the cross-sectional area of the pipe required to meet the required flow rate.< /p>

Formula: Q = A x v

In which:

  • Q: Volume flow rate (m3/s)
  • A: Cross-sectional area of tube (m2)
  • v: Steam velocity (m/s)

Assumed velocity for the following cases:

  • Flash vapor: 15 m/s
  • Saturated vapor:
    • Long distance travel: 25 m/s
    • Short distance travel: 30 m/s
  • Overheating steam: 30 - 40 m/s (depends on pipe length and pressure drop)
Steam velocity should not exceed the above values because it may cause a water hammer effect and greater pressure drop.
Based on the above formula, we have a steam pipe size table based on the following velocity method:

Disadvantages of the velocity method does not consider pipe length, which can lead to inappropriate pipe size selection for plants with different lengths. A pipe with a larger length will have a larger pressure drop than a smaller length for the same pipe size. We need to estimate the pressure drop for a given pipe length and verify if the same is true. within acceptable limits or not.

Pressure drop method

This method calculates the size reserve tube a above the allowable pressure drop in the system. This method is more complicated than the velocity method but gives more accurate results.

The pressure drop over a given pipe length must be 10% of the Steam Inlet Pressure or 1 Barg, depending on the value Whichever is smaller.


Regarding method selection, the velocity method is often used for simple systems with length short pipes, while the pressure relief method is preferred for complex systems with long pipe lengths or high precision requirements.

In short, steam pipe size plays a role important role in the steam distribution system. Choosing the appropriate pipe size will ensure the efficiency and safety of the system.