Coating Integrity Survey Using DC Voltage Gradient Technique at Korea Gas Corporation

The reliablity and applicability of various coating defect detecting techniques are investigated utilizing mock pipe. It is shown that both close interval potential survey and dc voltage gradient methods are impertinent as field techniques: They require considerable cathodic polarization in order to effectively locate the coating defects. DC voltage gradient with current interruption technique is recommended as a viable field method in that it is able to precisely locate the defects irrespective of CP condition. Utilizing this method field survey was undertaken for the KGC’s pipeline of 120 km and 106 assumed defects were located.