METHOD FOR DETECTING CORROSION SPEED OF METALLIC MATERIAL

摘要

PURPOSE:To measure the corrosion speed in corrosionproof environment directly at an actual spot in a short time by finding a fraction of anode reaction resistance at a measurement position from a potential measured value and a reference anode curve, and detecting the corrosion speed from a previously found relational expression. CONSTITUTION:A reference position 110 to be measured is set below LWL and the reference anode curve a0 is set at the position 110. The curve a0 is fixed electrically by using a corrosion speed detecting element. In an area Y where the influence of hydrogen production reaction can be ignored, the anode reaction resistance Ra of a steel pipe pit 41 corresponding to potentials of controlled four stages is measured. A solid line a1 and a broken line a2 drawn by extrapolating the solid line a1 are applied as the curve a0. Further, the corrosion speed detecting element is used to measure the potential of each position to be measured and a fraction of the anode reaction resistance is found from the potential measured values and curve a0. The corrosion speed (v) is calculated by using the equation I. Consequently, the corrosion speed in electric corrosionproof environment is measured directly at the actual site in a short time. In the equation, (v) is the corrosion speed (mm/year) of the metallic material and K is a proportion constant.