An Investigation on the Failure Risks in a Steam Cracking Plant

The paper concerns an experimental study performed at a petrochemical plant of Enichem, located in Porto Torres, in the north western area of Sardinia. The investigation performed was centred on a steam cracking plant, the output of which is mainly composed of ethylene, propylene, pyrolytic benzine, hydrogen, methane and ethane. The study was focused on the problems concerning the maintenance of the plant components and the risks associated with the plant failures. The analysis, accomplished on a time interval of five years, from 1999 to 2004, enabled the characterization of the plant components and of the whole productive system from the point of view of the risk; this allowed to determine, in each year, which components are associated to the highest values of the risk, what is the behaviour of the most critical components during the five years under exam, which parts of the plant deserve a deeper attention and more resources and what kind of failures are the worst in terms of real damage produced. At the same time, a criticality analysis was performed employing both the MAGEC method and the Fuzzy Logic approach. The listing of the plant critical components based on the two methodologies employed places in the first positions the same components identified in the risk analysis. Nevertheless, in the results obtained through the risk analysis, some basic differences mainly due to the introduction of the basic economic aspects, are registered.