"Carbon steel performance under high temp and sulfur gas exposure"

Question:

"What data is available for the performance of carbon steel at temperatures of nominally 700F in a trace sulfur gas environment. To compound the problem, the carbon steel is part of a air-to-air heat exchanger so the temperature profile would decrease within the exchanger. Alternately, we would use 316 SS in lieu of carbon steel. Also, gas phase water would be present."

Answer:

"Trace" amounts of sulfur gas needs to be more accurately defined in order to provide specific materials of construction recommendations regarding the use of carbon steel as a heat exchanger component. A potential corrosion mechanism is sulfuric or sulfurous acid corrosion during downtimes. If sulfurous or sulfuric acid condensation is a possibility, type 316SS may not be an optimum choice.