The category id of pipe curves. It will be OST_PipeCurves, OST_FlexPipeCurves, or OST_PlaceHolderPipes.
Namespace:
Autodesk.Revit.DB.Plumbing
Assembly:
RevitAPI
(in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0)
Since:
2014