Has anybody designed a sour gas line to an offsite DEA treater- about one mile away-.as bare carbon steel and without heat trace to avoid CUI issues?
Concern is internal corrosion due to heat loss and therefore acid condensation. What’s corrosion experience in this service?
I’m getting conflicting information on this; one non-US refinery consulted did not trace at all the fuel gas leaving the coker up to the amine system; a TX refinery traced it only until coker unit battery limit, and another nearby did full trace up to amine system. None report major corrossion issues, but for the ones traced and insulated, CUI is a long term concern.
I guess should pick the cheapest way…but isn’t it against corrosion’s theory?
After working with Corrosion team, considering tracing and insulating to prevent condensation and hence avoid corrosion highly depends on the levels of CO2 or NH4HS or O2 or HCl, which are the ones may cause significant corrosion rates. For Coker gas the only component found is CO2 typically below 0.5mol%; however, using the DeWaard-Milliams curve, the predicted corrosion rate based on the CO2 Partial Pressure and temperature is relatively low, and would be reduced further, as H2S also present somewhat reduces CO2 corrosion rates. Hence, the predicted corrosivity is not great enough to justify an absolute requirement for tracing and insulation.
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