Corrosion protection of steel offshore piles in a LNG terminal

The corrosion protection status of 45 steel tubular piles in the first stage of construction of a liquefied natural gas (LNG) terminal in China was investigated. The external appearance of the 45 piles was checked. Sections above water level were checked visually from a boat and sections below water level were checked by a diver. The investigation showed that most of the surface of the piles in the tidal zone was covered by continuous and dense marine growth, but corrosion was not found. Light cracking, chalking, color change, and local spalling were found. On 10 randomly selected piles, coating thicknesses were measured using an underwater coating thickness gauge. Measurements were taken at four sections on each pile, including one atmospheric zone, two tidal zones, and one submerged zone. Coating thicknesses are between 731 and 1,309 μm, with thicknesses between 731 and 993 μm in the atmospheric zones, between 746 and 1,309 μm in the tidal zones, and between 796 and 1,006 μm in the submerged zones.