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基于长输管线三层聚乙烯(3PE)防腐层失粘剥离现场开挖调查的情况,构建剥离防腐层下管道表面微区环境腐蚀模拟研究实验装置,研究华南酸性土壤环境条件剥离防腐层下管体表面的阴极保护和微区环境特征,采用微电极技术监测剥离区管线钢表面的局部电位和环境p H值的变化。结果表明,剥离区管线的有效保护距离随阴极保护电位负移而增加;在高电阻率酸性土壤环境中,剥离防腐层下的阴极保护仅限于破损点附近,剥离区深处管体处于自腐蚀状态;剥离防腐层下阴极保护有效性及其屏蔽程度可由剥离防腐层下微区溶液p H值判定。
Based on the investigation on the site excavation of the three-layer polyethylene (3PE) anti-corrosive layer in the long-distance pipeline under the conditions of digging-off and peeling off, an experimental device was set up to simulate the corrosion on the surface of the pipeline under the peeled off anti-corrosion layer. The cathodic protection and the characteristics of the micro-environment of the body surface were monitored. The microelectrode technique was used to monitor the changes of the local potentials and the environmental p H values on the surface of the strip steel in the peeled zone. The results show that the effective protection distance of pipeline in peel zone increases with negative cathodic protection potential. In high resistivity acid soil environment, the cathodic protection under peel-off coating is limited to the vicinity of the damage point. State; the effectiveness of cathodic protection under the peel-off coating and the degree of shielding can be judged by p H value of the solution in the peel-off coating under the micro-zone.