Corrosion Model of Carbon Steel Pipe on Manhole

Abstract

Many facilities were built underground to maintain communication, and they have been feared that corrosion of the inner surface of a steel pipe may cause failure in cable laying or reduct the seismic performance. To obtain long-term corrosion rate, a specimen made of steel pipe was placed in a manhole that is assumed to be close to the actual environment, and the corrosion rate was measured by inspecting the weight loss over four years. In addition to this, the specimen are observed with SEM and analyzed with XPS. There are some dense layers on specimen consist of FeOOH, Fe₃O₄, Fe（OH）₂CO₃. Because of dense layer, corrosion rate can be proportional to 1/2 power of time. The coefficients of the model equation were determined from the measured values.