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

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.

• H. Gholami
• M. Jalali Azizpour

• Stress Corrosion Crack
• Direct Assessment
• Disbondment
• Transgranular SCC
• Compressor Station.

[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