Irricad

Hello Jo!

We've been grappling with an issue for quite some time now. In our experience with designing main pipes using Irricad, we often find that the software tends to select pipes with larger diameters than we would typically choose to use. As a result, we frequently need to manually adjust the main pipes to better suit our needs.

Our approach is straightforward: we typically aim to tolerate approximately a 1.0 kg/cm² head loss at the main pipe under worst-case operational conditions. However, Irricad consistently selects pipes that result in head losses significantly lower than this threshold.

Our question is whether there is any way to adjust parameters within Irricad to exert greater control over the selection of main pipes. As it stands, it seems that the main pipe LP design lacks adjustable parameters for this purpose.

Any insights or suggestions would be greatly appreciated.

Thank you for your time and assistance.

Thank you for your question.

Mainline LP Design trades running costs (cost of power) against the cost of capital plus interest to find the most economic pipe selection for the system that will meet the control valve or mainline outlet pressure requirements.

You can turn off the "Trade capital costs vs running costs" option in Design|Design Parameters - Economic Parameters however the pipes will then be selected solely on meeting required pressure range, limited by the maximum velocity setting.

To assist LP to pick the smaller pipes you can:-
- set the cost of power high and the interest rate low in Design|Design Parameters - Economic Parameters
- ensure that suitable smaller pipe sizes are enabled in the database with the M usage code
- ensure that the price of pipes is up to date, or at least relative to each other (that is, larger pipes cost more and smaller pipes cost less)

Also be aware that the velocity limit may be restricting the LP Design algorithm so that smaller pipes are not considered, even though the end result may not be over the preferred velocity limit. To assist this set your "Maximum mainline velocity" higher in Design|Design Parameters - Hydraulic Parameters.

Note that if you do change the economic parameters significantly then this will affect the Economic reporting if this is of interest to you, as seen in the B.O.M with Costs, Zone/Mainline BOM, and Zone Summary/Mainline BOM reports.

The IRRICAD Team