In order to increase the amount of middle distillate and to improve energy efficiency, there is a trend in atmospheric distillation tower operations to reduce the tower top operational temperature and pressure. Directionally, crude oil processing move towards heavier crude oils, higher amounts of salts and longer operational terms. Also, there will be a trend in increasing chlorides levels in tower tops caused by a reduction or termination of caustic soda usage due to processing of residual oil

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... streams through hydrodesulfurization units to other cracking processes. It is desired to be able to understand and control this corrosion based on effective measurement in order to have stable long term operations in spite of this worstening corrosion environment in the tower overhead system. This review is about the various varification steps of applying this corrosion control technology on actual units in the field.