The objective of this paper is to present a technique based on Principal Component Analysis (PCA) for assessing and improving centrifugal pumps performance included in an oil refinery plant and subjected to different operating conditions. The procedure makes it possible to determine the critical operating factors influencing the reliability of the pumps. The model proposed was integrated in the normal operating practices of the refinery’s Maintenance Engineering Department: •during the design stage it was used to establish which parameters to focus on (and in which direction) to improve the reliability features of a plant or system; •during testing or, for existing plants or systems, to identify which aspects to test, or which elements to service. It is consequently useful tools both in the design and in the testing and servicing stages.