Studies on the metallographic inspection of HK‐40 reformer tubes

The paper summarises the merits and limitations of different methods used to determine the rejection criteria of the primary reformer tubes. It compares the microstructures as obtained on the outer surface of the reformer tubes with that observed in the transverse section in the regions of outer wall, midwall and inner surface. On the basis of these studies coupled with dimensional change measurements, the in situ metallographic technique has been used to monitor the condition of tubes in two reformation units and the tubes had given satisfactory service till the next turnaround as predicted.