Stress Corrosion Crack Identification with Direct Assessment Method in Pipeline Downstream from a Compressor Station

Authors: H. Gholami, M. Jalali Azizpour

Abstract:

Stress Corrosion Crack (SCC) in pipeline is a type of environmentally assisted cracking (EAC), since its discovery in 1965 as a possible cause of failure in pipeline, SCC has caused, on average, one of two failures per year in the U.S, According to the NACE SCC DA a pipe line segment is considered susceptible to SCC if all of the following factors are met: The operating stress exceeds 60% of specified minimum yield strength (SMYS), the operating temperature exceeds 38°C, the segment is less than 32 km downstream from a compressor station, the age of the pipeline is greater than 10 years and the coating type is other than Fusion Bonded Epoxy(FBE). In this paper as a practical experience in NISOC, Direct Assessment (DA) Method is used for identification SCC defect in unpiggable pipeline located downstream of compressor station.

Keywords: Stress Corrosion Crack, Direct Assessment, Disbondment, Transgranular SCC, Compressor Station.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1097014

References:

[1] ASME B31.8S (latest revision), “Managing System Integrity of Gas Pipelines” (New York, NY: ASME).
[2] ANSI/NACE Standard RP0204-2004(latest version), “Stress Corrosion Cracking (SCC) Direct Assessment Methodology” (Houston, TX: NACE).
[3] NACE Standard TM0109 (latest revision), “Aboveground Survey Techniques for the Evaluation of Underground Pipeline Coating Condition” (Houston, TX: NACE).
[4] Michael Baker Jr., Inc.” Stress Corrosion Cracking Study, Final Report”, Integrity Management Program Delivery Order DTRS56-02-D- 70036, January 2005,
[5] The Canadian Energy Pipeline Association(CEPA), “ Stress Corrosion Cracking Recommended Practice” 2nd Edition, an industry leading document detailing the management of transgranular SCC, December 2007,
[6] Golf Publishing Company, “ Handbook of Corrosion Protection, theory and practice of electrochemical protection process” , Third Edition, Houston TX, 1997