Nickel Aluminum Bronze (NAB) is frequently the material of choice for the fabrication of
equipment such as pumps, valves, etc. for seawater service. In general, the corrosion
performance of this alloy material in seawater is very satisfactory and its resistance to
cavitation is excellent. However, component failures have been occasionally encountered.
The present paper discusses the premature failure of a NAB Liquid Ring Vacuum Pump
(LVRP) at the seawater treatment plant of the Kuwait Oil Company (KOC). The failure
investigation consisting of metallographic examination of the alloy microstructure, hardness
profiles, and SEM microprobe analysis indicated that the cause of failure was attributable to
the use of a non-specific grade of NAB in an improperly heat treated condition and possibly
operational parameters. The corrosion morphology indicated that cavitation and erosioncorrosion
were the main damage mechanisms.
Keywords: Nickel Aluminum Bronze (NAB), Failure Analysis, Seawater Service