Methods and Applications of External Corrosion Degree Assessment for Urban Steel Gas Pipelines

External corrosion is the main reason which leads to steel gas pipeline leakage accident.Discussing the effective evaluation methods of pipelines external corrosion has some practical value in engineering for predicting the possibility of pipeline leakage,preventing initiatively the pipeline leakage accident and constituting reasonable protection countermeasures.The indexes in pipelines external corrosion evaluation are Determined,including soil causticity,anticorrsion coating performance,cathodic protection conditions,stray current and pipeline serving time.And the multi-level fuzzy evaluation method of quantitative evaluating of pipeline corrosion in non-excavation situation is established.Taking certain segment gas pipeline in Guangzhou city as an example,the excavation detection experiment indicates that the evaluation results of this method are reasonable.