Calculate Least Cost Pipe Diameter and Flow Velocity with Excel

Generally, engineers choose pipe diameters and flow velocities which minimize the total cost of the pipeline over the whole pipeline lifecyle.  The total cost is the sum of the capital costs and operational costs. 

This Excel spreadsheet calculates the least total cost pipe diameter and flow velocity for a pipe, given the desired construction material, flowrate, viscosity and density.

It uses the Generaux Equation and the empirical cost parameters as given the in the January 2010 article in Chemical Engineering "Updating the Rules for Pipe Sizing".  The Generaux Equation is an empirical correlation that takes into account the
  • annual depreciation and maintenance for the pipe
  • annual depreciation of the associated pumping equipment
  • installed cost of the pipe
  • fractional efficiency of pump
  • installation and fitting costs
  • energy cost to power the pump motor
  • friction in the pipe fittings
  • installation cost of the pump
  • cost of the pipe
  • number of operating days per year
  • taxes and other expenses
  • fluid density, viscosity and the desired flowrate
The calculation is iterative and uses Excel's Goal Seek Functionality.  

The spreadsheet enables you to choose from empircal cost parameters for 1998 and 2008, for a range of materials. Generally, least-cost flow velocities have decreased over time because energy costs have increased.

  1. Specify the construction material (choose either Carbon Steel, Stainless Steel, Alumimum or Brass), fluid density and fluid viscosity
  2.  Click the Optimize button to initial Excel's Goal Seek function


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