4. Conclusions
In this study, the principal causes of corrosion failure in the plate heat exchanger (PHE) of Jam Petrochemical Complex (JPC), Asalouyeh, Iran, were evaluated via visual inspection, optical and scanning electron microscopy, energy dispersive Xray spectroscopy (EDS), thermo-scan analysis, and measurement of chloride and sulfide content of the waters. It was found that the chloride ions build-up in crevices formed between plates and gaskets (at high temperatures), is the main reason for the occurrence of SCC. The suspended soil of the service water settled in the crevices between gasket and plate and provides a favorable position (dead zone) for building-up of the chloride ions. When the level of chloride ions in the water is low, the evaporation of water in the crevices leads to chloride ions build-up. Moreover, the high temperature of the transport water outlet and cooling water inlet results in the acceleration of this building-up. By chloride ions concentration in the crevices, the pitting corrosion under gasket seat occurs. In addition, the simultaneous presence of chloride and sulfide ions intensifies the SCC failure in the heat exchanger plates.
