CORROSION INVESTIGATION BY ELECTRICAL MEASUREMENTS

Not long ago, the East Bay Municipal Utility District of Oakland, California, faced and solved a stubborn corrosion problem in its large twin‐transmission main. The problem arose originally when the District built its second Mokelumne Aqueduct running parallel with the first for about 83 miles. Shortly after this new line was built, leaks began to appear in the older aqueduct, even though it had been protected by cathodic devices for the previous 15 years. Mr. Hendrickson, who was appointed to solve the problem, states that corrosion in a pipeline is caused by an electric current discharging electrolytically from the pipe to the soil. The source of this electric current may be galvanic or of local action, or it could also be man‐made such as a stray railway current. Mr. Hendrickson's findings are given below from the paper he subsequently gave at the Annual Conference of the National Association of Corrosion Engineers.