CORROSION PROTECTION METHOD OF INTERNAL SURFACE OF STEEL PIPE

PURPOSE:To prevent corrosion of the internal surface of a steel pipe in a marine steel structure having steel pipe structure by sealing sea water, a deoxidizer and a flotation agent into the steel pipe from a filler hole formed to the upper section of the steel pipe and hermetically sealing the filler hole. CONSTITUTION:A steel-pipe upper cover 5 is fixed onto a steel-pipe pile body 4, the inside of which is hollowed, by welding a filler hole 2 is formed to the cover 5, and a female screw mounted to the cover 5 is screwed to a male screw fitted outside the filler hole 2. Sea water 6 is housed up to approximately half height from the filler hole 2, a deoxidizer consisting of iron powder and a flotation agent composed of sawdust are stored in a steel pipe pile 3, a cover 7 is screwed to the filler hole 2, and the cover 7 is closed. The flotation agent functions as the keeping of metal powder at a place (a water surface), where the internal surface of a steel pipe 1 is easy to be corroded. The deoxidizer bonds with oxygen in air and in water, and oxygen required for corroding the steel pipe 1 is wasted, thus inhibiting corrosion in the steel pipe 1. Accordingly, the internal surface of the steel pipe 1 can be protected against corrosion by a simple means.