Electrical heat taracing design

Plenty of details here but not enough information about what one is attempting to do. For an example, if you were inspecting this cryptic rig and found that these were the dimensions and the materials found, then your inspection would be exactly correct. One would next need to examine the design plan documentation to see if the correct parts were utilized to approve or disapprove the inspection. So as you can see, this can or cannot be correct only when one knows the task in hand.

It is not possible to say without knowing about the properties of the oil in the pipe, its inlet and outlet temperatures, and its flowrate.

For what purpose it trace heating tape being applied? Oil pipelines don't usually freeze up!