Sizing a Gas Pipeline Using a Mach Number Sizing Criteria in PIPE-FLO® Advantage 17
Different companies use different design criteria to size a pipeline based on the application of the piping system. Depending on the application, a pipe may be sized based on a design velocity, pressure drop or head loss per 100 units of length. Similarly, the Mach Number is used to size gas pipelines. This functionality is added to the Compressible Pipe device in PIPE-FLO® Advantage 17, providing more flexibility in designing piping systems for gas applications.
Selecting a Mach Number Design Criteria
As gas flows down a pipeline, its static pressure, temperature, and density drops resulting in an increased velocity and Mach Number for a given mass flow rate. The higher the Mach Number, the greater the energy loss and total pressure drop. For some applications, a gas can be considered to flow incompressibly as long as the Mach Number is under about 0.2.
In PIPE-FLO Advantage, sizing a pipeline by a maximum Mach Number is done by first setting the sizing criteria in the Pipe Specification or in the Pipe Sizing Calculator dialog. To set in the sizing criteria in the Pipe Specification Properties, open the Pipe Properties dialog for the desired specification and choose Mach number from the drop down in the Sizing Criteria section and enter the desired value for all Compressible Pipes using that specification. To set unique values for a specific pipe, open the Pipe Size Calculator for that pipe after a Fluid Zone and Pipe Specification have been assigned. If Sizing Criteria were entered for that Pipe Specification, those will be the default values which can be changed.
In the Inputs section of the calculator, enter a design flow rate and estimated static pressure at the location where the Mach Number is expected. The Pipe Size Calculator will display the calculated diameter, the selected nominal size, the inner diameter of the selected size, and the calculated flow rate at the selected size, Mach Number criteria, and static pressure. These results can be evaluated to determine whether to choose the selected nominal size or select a smaller or larger size.