The LineSeries3D API doesn't allow setting the number of sections of the line. In other words you can't define a "circular tube" using the default rendered geometry. However, you can achieve your requirement, by creating a custom geometry and passing it to the DefaultLineVisualGeometry property of series. Read more about this in the LineSeries3D help article
Get quickly onboarded and successful
with your Telerik and/or Kendo UI products with the Virtual Classroom free technical training, available to all active customers. Learn More.