Failure analysis of a Nickel-Aluminum-Bronze (NAB) sleeve valve in seawater effluent line of one of the refineries in Kuwait was conducted. Microscopic examination of the failed components, chemical analysis of valve material, identification of corrosion products, microstroctural examination, microhardness tests and morphological examinations by the scanning electron microscope (SEM) were conducted to determine the cause of failure. Analysis of results indicated that the causes of failure can be attributed to a combination of erosion and cavitation corrosion as well as preferential phase corrosion of the alloy material. Cavitation corrosion resulted from operating the valve at or slightly below the critical cavitation index.
Keywords: failure analysis, seawater, erosion-corrosion, cavitation, preferential phase corrosion.