柴达木盆地盐渍土环境管道防腐层质量及腐蚀分析

Pipeline Anticorrosive Coating Quality and Pipeline Corrosion Analysis in Salty Soil Environment at Qaidam Basin

为明确柴达木盆地盐渍土环境土壤腐蚀性,做好管道防腐的第一道防线,对柴达木盆地盐渍土环境管道防腐层质量与管道腐蚀情况进行了分析。结果表明,盆地内青海油田的大量油气水集输管道周边土壤含盐量在0.044%~45.8%(质量分数)之间,根据土壤腐蚀性检测评价结果,盆地内盐渍土土壤腐蚀性等级在2级“较弱”至3级“中等”之间,土壤腐蚀性整体不高。目前青海油田集输管道外防腐层主要是3PE、熔结环氧粉末和EP重防腐漆,施工损伤、磨损和补口质量差是防腐层损伤主要原因。通过现场开挖验证发现,湿度和氯离子含量、含盐量是影响管道腐蚀的重要因素,在干燥环境中,无论土壤含盐量、氯离子含量等其他因素强弱,管道腐蚀均不严重;在湿润环境中,土壤氯离子含量、含盐量对腐蚀有较大影响,当其含量较低时腐蚀较严重,呈现点蚀特征,当土壤氯离子含量、含盐量较高时,腐蚀轻微。

In order to clarify the soil corrosivity of salty soil environment at Qaidam Basin and do well the first defense line against pipeline corrosion, the quality of pipeline anticorrosive coating in salty soil environment and pipeline corrosion at Qaidam Basin are analyzed. The results show that the soil salinity (mass fraction) around the large amount of oil, gas and water gathering and transportation pipelines in Qinghai Oilfield is between 0.044% and 45.8%. According to the results of soil corrosivity test, the soil corrosivity of salty soil in the basin is between grade 2 "weak" and grade 3 "moderate", and the overall corrosivity of the soil is not high. At present, the main external anticorrosion coatings of gathering and transportation pipelines in Qinghai Oilfield are 3PE,fusion epoxy powder and EP anticorrosive coating paint, and the main reason of anticorrosive coating damage are construction damage, abrasion and poor joint coating quality. Through the verification of field excavation, it is found that humidity and chlorine ion/salt content are important factors affecting pipeline corrosion. In the dry environment, pipeline corrosion is not serious regardless of the strength of factors such as soil salt content and chloride ion content. In the humid environment, soil chlorine ion content and salt content have a great influence on corrosion. When the content is low,corrosion is more serious,showing pitting erosion characteristics. When soil chlorine ion content and salt content are high,corrosion is slight.