Problem

A conduit's Catalog Class is changing after computing constraint based design (to something different from what was initially selected.)

Background

This can occur if you have more than one Catalog Class with the same Shape and Material. The constraint based design solver will select available pipe sizes from any Catalog Class that has the same Shape and Material.

This expectation is due in part to User Defined conduits which can also be designed (see article link below) but do not have a catalog class property. So, constraint based design must consider the shape and material of the user defined conduit and select any available size from any catalog class that has the same shape and material (and there could be more than one with the same shape and material).

For example here we have six Catalog classes, each with the same shape and material.

Three conduits all have "Class 2" initially selected:

Here is the result of the constraint based design run. Note each conduit now uses sizes from different Catalog Classes:

Solution

In this situation, if you need to force conduits to stay within the same class during design, modify the label of the Material of each class to be unique. For example add a suffix. Continuing with the same example as above:

Now, all are using the same catalog class post-design:

Reference #372197

See Also

"Conduit Catalog should contain conduits that are available for design and with same Conduit Shape/Material..."