Integrating Iow in the Estimation of the Risk of an Atmospheric Distillation Unit by Using a Bayesian Network

Sulfidation and naphthenic acid corrosion are well-known damage mechanisms, hence, there are many ways to deal with them. These mechanisms are common in refineries and petrochemical industry due to the treatment of sour crude oils. The industrial manager usually takes advantages from the use of sour crude oils from an economic point of view, but at the same time he/she has to cope with sulfidation and naphthenic acid corrosion because of their implication on safety. A recent study, which is based on the use of a bayesian network for the management of the previous mentioned corrosion mechanisms and the dynamic updating of the Residual Useful Lifetime (RUL), has been improved. The new approach integrates the estimated RUL in the risk evaluation, giving a dynamic update of the position of the equipment in the risk matrix by introducing the performance coefficients (KPI – Key Performance Indicators) belonging to the Asset Integrity. The approach has been applied to the pre-heating section of an atmospheric distillation unit of the Milazzo Refinery. The parameters that have been taken into consideration are the material metallurgy, the characteristics of feedstock, the temperature and the number of inspections carried out during a reference period. An attempt has been made to link the approach to the integrity operating windows (IOW), which have been already implemented in a homemade software by the I&T department of the refinery.