Abstract: The potential distribution of tank bottoms is an important index to appraise effectiveness of cathodic protection(CP).Theoretical calculation of bottom potential is valuable when measurement is difficult or impossible.The potential variation caused by flowing currents along tank bottoms is too small to have effect on potential distribution.The potential distribution of tank bo ttoms mainly depends on ground electric field.The equation of potential on tank bottom could be derived from electric field theory of stable currents.When the anodes in CP are far from the protected tank,the relationship of potential and distance to bottom center is simplified as a third power parabolic-like equation.These conclusions has been confirmed by both laboratory data and insitu measurement data.The effect of some parameters in analytical equation is also discussed.

Key words: cathodic protection, ground storage tank, tank bottom, potential distribution, derivation, experimental verification

摘要： 阴极保护时,金属储罐外侧罐底保护电位分布是衡量罐底保护效果的重要指标.鉴于实际测量的困难,理论计算常是辅助手段之一,而用稳流电场理论分析罐底外侧阴极保护电位的分布,发现沿罐底流动电流造成的电位变化在微伏级,对阴极保护电位分布无实际影响.保护电位取决于地电场.当阳极离罐较远时,理论推导表明,阴极保护电位与离圆心距离的关系呈类似立方抛物线方程的形式,室内模拟试验以及文献资料提供的数据证实了这个结论.根据解析公式还简要讨论了各种参数的作用.

关键词: 阴极保护, 地面储罐, 罐底板, 电位分布, 公式推导, 实验验证