Pipeline External Corrosion Confirmatory Direct Assessment
|Publication Date:||22 October 2010|
This standard covers the NACE external corrosion confirmatory direct assessment (ECCDA) process for buried onshore ferrous piping systems. This standard is intended to serve as a guide for applying the NACE ECCDA process on typical pipeline systems.
This standard was written to provide flexibility for an operator to tailor the process to specific pipeline situations.
ECCDA is a continuous improvement process. Through successive applications, ECCDA should confirm conclusions drawn from previous assessments and identify and address locations at which corrosion activity has occurred, is occurring, or may occur.
ECCDA provides the advantage and benefit of locating areas where corrosion is likely to occur in the future rather than only areas where corrosion has already occurred.
Comparing the results of successive ECCDA applications is one method of evaluating the effectiveness of the ECCDA process, as well as the external corrosion direct assessment (ECDA) process, and demonstrating that confidence in the integrity of the pipeline is continuously improving.
ECCDA was developed as a process for improving pipeline safety. If external corrosion is a threat to be evaluated, ECCDA can be used to validate previous assessment conclusions or determine whether the reassessment interval is still appropriate.
ECCDA applications can include but are not limited to assessments of external corrosion on pipeline segments that:
Can be inspected using other common inspection methods (such as in-line inspection [ILI] or pressure testing).
Have been inspected using other inspection technologies as a method of managing future corrosion.
Have been inspected with another inspection technology as a method of establishing a reassessment interval.
ECCDA may detect other pipeline integrity threats such as mechanical damage, stress corrosion cracking (SCC), and microbiologically influenced corrosion (MIC). When such threats are detected, additional assessments or inspections must be performed. The pipeline operator should use appropriate methods such as ASME(1) B31.4, ASME B31.8, ASME B31.8S, and API(2) 1160 to address risks other than external corrosion.
The ECCDA process has limitations, but many pipelines can be successfully assessed with ECCDA. Precautions should be taken when these techniques are applied, just as with other assessment methods.
This standard may be applied to poorly coated or bare pipelines in accordance with the methods and procedures included in NACE SP0502, NACE SP0207, and NACE Standard TM0109. Poorly coated pipelines are usually treated as essentially bare if the cathodic current requirements to achieve protection are substantially the same as those for bare pipe.
This standard may be applied only to pipelines that have been previously inspected by techniques capable of identifying and locating external corrosion.
For accurate and correct application of this standard, the standard shall be used in its entirety. Using or referring to only specific paragraphs or sections can lead to misinterpretation and misapplication of the recommendations and practices contained herein.
This standard does not designate practices for every specific situation because of the complexity of conditions to which buried piping systems are exposed.
The provisions of this standard should be applied under the direction of competent persons who, by reason of knowledge of the physical sciences and the principles of engineering and mathematics, acquired by education and related practical experience, are qualified to engage in the practice of corrosion control and risk assessment on buried ferrous piping systems. Such persons may be registered professional engineers or persons recognized as corrosion specialists or cathodic protection (CP) specialists by organizations such as NACE or engineers or technicians with suitable levels of experience, if their professional activities include external corrosion control of buried ferrous piping systems.
(1) ASME International (ASME), Three Park Ave., New York, NY 10016-5990.
(2) American Petroleum Institute (API), 1220 L St. NW, Washington, DC 20005-4070.