Risk-Based Inspection and its Application to the Optimization of Chemical Plants

The correct design of a chemical plant does not necessarily imply a fully safe facility. Without the adequate inspections and maintenance plans, certain equipment sooner or later will collapse as a result of wear, fatigue, corrosion or other circumstances. Thus, an effective inspection plan is one of the tools considered in the operation safety programs to reduce the risk of accidents. Effective inspections can reduce risk through the decrease of the failure frequency by establishing corrective and preventive measures, which are taken into account once the inspection has identified potential failures. Generally speaking, as the investment in safety increases, the risk associated to a given plant or activity decreases and the cost of the potential accidents that can occur will probably also decrease. A methodology is proposed to optimize the inspection plans of a facility through the introduction of risk analysis as a variable. An objective function is thus established to analyse the variations in the overall costs, including the cost of the procedure and the cost of the potential accidents. This leads to an optimum situation in which the overall cost (inspection plus accident consequences) reaches a minimum. As an example, the methodology is applied to one case concerning the transportation of a toxic material. The cost of accidents has been shown to decrease significantly when at least one inspection is applied in the lifetime of the equipment, this influence being of course more important when the effectiveness of the inspection is higher.