Direct Assessment is a very good method of determining if external corrosion is a potential
problem on a coated and cathodically protected pipeline. The type of coating can be critical in
finding where and if external corrosion is a problem. Many times external corrosion can not be
located through over the line surveys because cathodic protection potentials indicate adequate
protection, therefore there should be no external corrosion, yet internal line inspection (ILI)
tools find corrosion. Many times the cause and age of the corrosion are not properly evaluated
when performing direct assessment of these pipelines. This paper will discuss common sense
evaluation methods for determining why external corrosion still exists and in some cases
continues even with apparent adequate cathodic protection.
KEY WORDS: Cathodic protection, CP shielding, Coating Deterioration, ECDA, DCVG, ACVG