The first scientific investigation illustrating stages of failure beginning with simple metal discoloration to catastrophic failure, and finally revealing the true causation of failures plaguing the drum furnace.

1) Simple metal discoloration in the typical bull's-eye pattern.



2) More bull's-eye discoloration with slight swelling.



3) Bull's-eye discolorations begin to blend into each other with increased swelling.



4) Metal now begins to open from complete loss of structural integrity.



5) Heat exchanger also begins to separate from back section.



6) Catastrophic failure with readily apparent causation.