Study On Prediction Technology For Residual Lifetime Of Corroded Gas Pipeline In Service

Firstly, research achievement and state of corrosion residual life prediction for the pipeline at home and abroad were introduced. The characteristics of corrosion residual life prediction for long-distance transport pipeline were summarized. The existing methods of corrosion residual life prediction were analyzed and compared, then were classified.Secondly, corrosion defects were classified as three types: general corrosion, local corrosion and pitting corrosion. And the geometric shapes of all corrosion defects were modeled.Then, the statistical analysis for the residual life of the whole pipeline and pipe section was done from the direction of probability statistics, the statistic rule of which was found.Following the above, rates of electrochemical corrosion of soil to pipeline were discussed on the basis of electro chemical theory. The different electrochemical models of corrosion rates were done aiming at different corrosion types. Through residual strength evaluation was made for pipeline, defect dimension, namely defect depth, axial size and loop size, was checked in three directions. Limit corrosion dimensions were determined. The residual lives of corrosion defects of different types were got basing on the electrochemical models of the corrosion rates and residual strength evaluation. This paper put the emphasis of the prediction method basing on corrosion rate.Finally, the embrittlement of materials will be induced by aging effect of metal and corrosion damage, which will change the plasticity of materials and make mechanical capability decline. So the paper studied on the residual life of pipeline from the direction of accumulated damage and capability attenuation, and the model of strength reserve ratio and the model of capability attenuation were respectively done.