A significant effort has been devoted in the last decades to increasing safety in the chemical industry and related activities. Hazard identification and risk analysis are key aspects to reach this target. Safety can be incorporated at any stage of design or operation, but the best results are obtained if it is incorporated at the earliest possible stage of the design process. In any case, a significant investment must be made. 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 may occur will probably also decreases. Thus, a situation arises in which costs may decrease (the cost of accidents) or increase (the cost of investing in safety) as a function of a given variable. Therefore, an optimization is possible to attain the “best” situation in terms of both cost and risk. This consideration can be also applied to the on-land transportation of hazardous materials by pipeline. This is the subject of this contribution. An efficient way to reduce the consequences of accidents in pipelines is through the proper design of the whole system; indeed, one of the points which must be decided in this area is the installation of blocking valves at appropriate distances. These valves are installed to allow emergency shutdowns to interrupt the flow of substance and to isolate the section where the loss of containment takes place. The presence of this shutdown system separates the pipeline in sections, so that in the case of pipe rupture the amount released is limited to the content between two consecutive valves. Usually the location of these devices is set by heuristic criteria. However, on one hand, if there is an overdesign by the use of an excessive number of valves, the capital cost of equipment increases excessively; on the other hand, if few valves are installed there is the risk of suffering accidents with serious consequences. Thus, an interesting possibility is to improve the design of this system applying risk-based optimization criteria. Therefore, an optimization methodology has been proposed to solve this conflict: an objective function is established to analyze the variations in overall costs, including the cost of the investment (with specific reference to blocking valves) and the cost of accidents. Restrictions concerning the tolerable risk concept are also taken into account. This leads to an optimum situation in which costs are kept to a minimum. As an example, the methodology is applied to a specific case (the transportation of gasoline by pipeline).

Risk-based optimization of the design of on-shore pipelines shutdown systems

BONVICINI, SARAH;COZZANI, VALERIO
2010

Abstract

A significant effort has been devoted in the last decades to increasing safety in the chemical industry and related activities. Hazard identification and risk analysis are key aspects to reach this target. Safety can be incorporated at any stage of design or operation, but the best results are obtained if it is incorporated at the earliest possible stage of the design process. In any case, a significant investment must be made. 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 may occur will probably also decreases. Thus, a situation arises in which costs may decrease (the cost of accidents) or increase (the cost of investing in safety) as a function of a given variable. Therefore, an optimization is possible to attain the “best” situation in terms of both cost and risk. This consideration can be also applied to the on-land transportation of hazardous materials by pipeline. This is the subject of this contribution. An efficient way to reduce the consequences of accidents in pipelines is through the proper design of the whole system; indeed, one of the points which must be decided in this area is the installation of blocking valves at appropriate distances. These valves are installed to allow emergency shutdowns to interrupt the flow of substance and to isolate the section where the loss of containment takes place. The presence of this shutdown system separates the pipeline in sections, so that in the case of pipe rupture the amount released is limited to the content between two consecutive valves. Usually the location of these devices is set by heuristic criteria. However, on one hand, if there is an overdesign by the use of an excessive number of valves, the capital cost of equipment increases excessively; on the other hand, if few valves are installed there is the risk of suffering accidents with serious consequences. Thus, an interesting possibility is to improve the design of this system applying risk-based optimization criteria. Therefore, an optimization methodology has been proposed to solve this conflict: an objective function is established to analyze the variations in overall costs, including the cost of the investment (with specific reference to blocking valves) and the cost of accidents. Restrictions concerning the tolerable risk concept are also taken into account. This leads to an optimum situation in which costs are kept to a minimum. As an example, the methodology is applied to a specific case (the transportation of gasoline by pipeline).
2010
Proc. 6th European Meeting on Chemical Industry and Environment
235
244
H. Medina; J. Arnaldos; J. Casal; S. Bonvicini; V. Cozzani
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/91939
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