The Utility Network Solutions for Stormwater have "diameter", "height", and "width" fields on the Stormwater Line feature class. This pairs well with the "pipeshape" attribute, where pipes with "pipeshape" set to "Circular" would typically use "diameter", while pipes with other values for "pipeshape" would likely use the "height" and "width" fields.
The Utility Network Solutions for Sewer (Expanded ) has a "mainshape" attribute on the Sewer Line feature class (with similar domain values as the "pipeshape" attribute in the Stormwater solution), but only a "diameter" field. Non-circular pipes are less common in Sewer than Stormwater but do exist. My organization has a number of rectangular "box" pipes on our very large interceptors (especially when crossing under creek beds, stormwater pipes/culverts, or large diameter water pipelines. We also have some D-shaped pipes and oval pipes (again to deal with crossing under other utilities).
Another consideration is that the NASSCO PACP standard for CCTV inspection uses height/width fields (and does not have a diameter field). This allows PACP inspections to accommodate all shapes of pipelines that might be inspected. We are in the process of implementing PACP for all CCTV inspections going forward and I am trying to decide how best to round-trip our UN sewer pipeline asset data the CCTV software (ITpipes in our case) and back.
