The line class specification for the system to be analyzed, calls for carbon steel pipe with 8mm carbide overlay (2 passes) with a corrosion allowance of 1.5mm.
Since the overlay has no benefit towards the pipe's strength and is there for abrasion resistance only, can I consider modeling the pipe with an increase in corrosion allowance? IMO that will account for loss of strength in the 'contaminated' cross-section of the pipe, where the first pass will modify the base material of the pipe. If so, what is a sensible value to consider? For safety reasons, I was going to suggest a total corrosion allowance of 3mm.