Ernie Klechka Comment

Richard,

I really liked you NACE presentation. Are the photographs available for inclusion in the CCCP class?

I do disagree with your comments that IR drop is not important. As you are aware we can use IR drop to find stray current on pipelines.

You also seem to imply that IR drop is a constant. You and I both know that IR drop will change in current pickup and discharge areas, near anode ground beds, and at areas with high current demand.

I agree that much of the problem centers around shielding. Coating that shield the pipeline cause erroneous conclusions concerning cathodic protection. Probably the area of shielding that causes the most concern is casings. However, shielding is not the only problem on pipelines.

Your slides show several poorly coated field welds. To me this points to poor field coating repair practices. Sure shrink sleeves can be poorly applied or subject to soil stresses that cause disbondment and shielding, but the cathodic protection system should not be allowed to be compromised because of a poor coating. A good impressed current cathodic protection system can through some current under a disbonded coating or at least increase the pH.

I think we should use the IR drop and not just “consider the IR drop.” We can use IR drop to find pickup points, discharge points, AC and DC interference, and many other potentials damaging conditions.



ERNEST W. KLECHKA P.E. ( ALASKA AND OHIO)