牺牲阳极对20号管线钢内腐蚀的阴极保护效果及影响因素

Cathodic Protection Effect of Sacrificial Anode on Internal Corrosion of 20 Pipeline Steel and Its Influencing Factors

针对集输管线和井场出站段管线易发生内腐蚀,且无法有效实施内穿插或挤涂等内防腐蚀措施,通过模拟计算和室内试验研究了不同牺牲阳极对20号管线钢内腐蚀的阴极保护效果,其中包括带状锌合金,环状铝合金和棒状铝合金三种阳极。结果表明:随着离牺牲阳极的距离增加,管线内壁受牺牲阳极的保护作用下降;对于直径为159~308 mm且无内防腐蚀层的管线而言,牺牲阳极的单侧保护距离为3.10~3.45 m;不同形状牺牲阳极均表现出了极限输出电流,其中环状和棒状阳极的预测寿命可以达到5 a的设计要求;室内试验结果与模拟计算结果吻合,此外,由于钙镁沉积,阳极输出电流会随时间逐渐减小,当阳极应用于现场时,实际消耗速率较低,其使用寿命会有所延长。

Due to the high possibility of internal corrosion occurring in gathering pipelines and outlet pipelines of oilfield,and lack of practical anti-corrosion measures such as internal penetration or extrusion coating for internal corrosion protection in field,the protection effects of different sacrificial anodes on 20 pipeline steel internal corrosion were investigated,including strap zinc alloy,ring and stick shapes of aluminum alloy.The results show that the protection of sacrificial anode for internal wall of pipeline decreased with the increase of distance from sacrificial anode.For the pipes in diameter from 159 mm to 308 mm and without internal coatings,the protection range on one side of anode could reach 3.10 m to 3.45 m.Every shape of anode presented a limit current;the predicted lifetime of the anodes in a ring shape and a stick shape could meet the design lifetime of 5 years.Experimental results show a good agreement with simulation results,also indicating that the anode output current decayed with time because of calcareous deposit,and the anode in field should be expected to have a longer lifetime than the predicted one from simulation.