Abstract: To seek the reasons of corrosion leaking of B10 copper nickel alloy seawater tube in a ship, the failure analysis of the flange near a seawater pump was proceeded by field checking, composition analyzing, microstructure observation and corrosion tests. The results showed that the composition and microstructures of the B10 tube met the requirements of the design. The static corrosion rate and erosion rate of the B10 were in the normal range. The electrolysis experiment indicated the stray current generated by the anti-fouling system in the ship probably contributed to the leaking of the B10 tube.