Tube failures due to chloride attack have occurred with increasing frequency within both the reactor circuit and fractionation section of high severity hydroprocessing units. The fractionator feed preheat exchangers are particularly susceptible to chloride attack. This susceptibility develops when poor oil/water separation provides a mechanism to transfer
chlorides from the reactor section into the fractionator feed stream. This paper describes the corrosion experience in the fractionator feed preheat exchangers of three hydroeracking units and reviews the materials and process modifications instituted to manage the corrosion severity.
Keywords: Hydroprocessing, hydrocracking, ammonium chloride, C1SCC, boil-dry conditions