As composite repair systems continue to become a routine repair option utilized by the process piping and pipeline industryfor the repair and rehabilitation of piping systems the demands on all aspects of these systems are increasing as well. The most commonly requested information on these repair systems is how to classify their performanceand validate them for fitness for service.This paper reports on a series of analytical and experimental studies performed validate the difference in performance between epoxy and polyurethane composites. Analytical studies were performed using traditional Shell Model Solid Model and FEA simulations. Experimental composite sleeve experiments were performed to determine the strain reduction efficiency of different composites. The traditional shell model was found to underestimate the strains in the repair which leads to higher stresses in the substrate pipe. Solid model and FEAmodels had close correlation and further tests are needed to determine missing material properties. The properties observed to make a difference in performance were the modulus of the resin resulting void content in the composites and whether the repair was bonded to the substrate. Epoxy composites which where bonded with a primer were observed to have the best performance. Composites with high NCO polyurethane resins were found to have the lowest performance. The results of this study may help owners and operators to make decision concerning the material properties required for repair.