The Science Underlying Successful ECDA

External Corrosion Direct Assessment (ECDA) is a powerful tool for assessing integrity of a pipeline.  The procedure is particularly valuable for pipelines for which other integrity assessment methods such as pressure testing and in line inspection tools are not practical.  In addition, unlike pressure testing and in line inspections that looks only backward in time, ECDA looks forward in time in that it provides insight into the present and future levels of mitigation. 

The ECDA procedure is based on selecting sites for excavation that are the most integrity compromised within an ECDA region.  If these sites are incorrectly selected, the ECDA procedure is compromised.  The operator would conclude that the pipeline had integrity when, in fact, it might have critical flaws at other locations within the ECDA region.

This paper, using fundamental electrochemical and engineering principles, lists the conditions that must be met in each of the four steps of the ECDA process to assure that any loss of integrity on the pipeline would be detected.