Non-uniform corrosion characteristics of the steel pipe pile exposed to marine environments

Steel pipe piles are commonly used as structural members in offshore construction steel trestles, and they may be imposed with serious corrosion threats. This study examines the corrosion characteristics of steel pipe piles which have been existing in the East China Sea for about five years. Nine samples were collected from the splash, tidal, and immersion zones, and cleaned and scanned by a laser scanner. Then they were reverse-modelled, 3D coordinates of the surfaces were generated, and the remaining thickness was calculated. Based on the surface height data, the waviness component was filtered while the roughness component was retained for each surface, and the topographic parameters were calculated and compared. The results reveal that the remaining thickness and the roughness of the steel pipe pile both showed non-uniform features. The steel pipe pile experienced double-sided corrosion in the splash and tidal zones, whilst it only experienced one-sided corrosion on the outer surface in the immersion zone. The severest corrosion damage was observed in the splash zone. Besides, the extreme value analysis results indicated that the minimal values of the remaining thickness in all zones conformed to the generalized extreme value distribution.