Stress Corrosion Cracking (SCC) can develop at hot spots, including where the heat tracing attaches to pipe
Caustic
Where dew point corrosion often occurs
Overhead Fractionation
Potential for none or very few CMLs on the circuit
Olefin Cold side, Anhydrous Ammonia
Relatively Uniform corrosion
Sulifdation, Sour Water
Valves that should be inspected for thermal fatigue
Cat Reformer