Urban Buried Gas Steel Pipeline Coating Inspection Evaluation Techniques And Test Software Development

With the fast economic development, pipe transportation is increasingly used for water, gas and heat supply in our country. The pipelines have to be exposed to the soil corrosion for a long time, which often leads to corrosion failures or even accidents causing heavy damages to mankind and environment. Aimed at detecting the coating defects of buried steel pipelines, this paper reviewed and compared several coating defects survey techniques now available in the world, and summarized their survey characteristics. Equipped with the experiences of field practices, the author presented a new method of coating defects survey method. Based on the AC current survey theory, the model of circuit between pipeline and ground was proposed.In this paper, classification assessment methodologies of the safety quality for the protective coating of the buried ferrous pipelines were also summarized. The class level and classification method as well as the assessment indicator were given. Parameters and the level values of the classification assessment for the petroleum asphaltum coating by using AC/DC Current Attenuation Survey were also proposed.