Corrosion surveys of steel pipe piles at Nokyo-pier at Komatsujima Harbour, which had elapsed 17 years, and at 9-gochi pier at Nagoya Harbour, which had elasped 13 years, have been carried out. The following results were obtained:
(1) Maximum corrosion rates on the steel portions where had been abraised by old tires as fender were about 0.7 mm/y. On the other hand, on the surfaces of steel pipe piles without fenders, pitting corrosion occured at MLWL and maximum corrosion rates were about 0.5mm/y (Komatsujima harbour).
(2) Mean corrosion rates were about0.2 mm/y and maximum corrosion rates were about 0.4 mm/y at splash zone, mean corrosion rates about 0.25 mm/y and maximum corrosion rates about 0.45 mm/y at MLWL, and mean corrosion rates about 0.1mm/y and maximum corrosion rates dbout 0.2～0.3 mm/y(Nagoya harbour).
(3) By using extreme value probability plots of the thickness loss of pipe piles, estimation of maximum corrosion amount at MLWL and in mud zone and comparison of corrosion tendencies at several corrosion environments were done.