Dangers of Cathodic Shielding

摘要

Pipeline operators spend millions on cathodic protection systems. These systems are designed to give backup protection in the event of failure of the primary corrosion coating system.rnThe problem is that today, many operators are using primary corrosion coating systems which, if and when they fail, can actually block the backup protection of CP currents.rnThe most obvious example of shielding corrosion coatings are those with high dielectric strength, such as shrink sleeves, tapes, and other solid film backed materials. The very same high dielectric properties which the industry thought to be desirable for many years have now been found to cause CP shielding. Unfortunately, solid film back coatings are widely used today on girth welds, where application errors are most common and the coating most likely to fail.