Stress Corrosion Cracking Direct Assessment (SCCDA), specified in NACE SP0204-2008, was developed to improve pipeline safety and reduce the threat of stress corrosion cracking (SCC) on onshore petroleum pipeline systems. The SCCDA program can be utilized as a primary technique for difficult to pig pipelines and as a supplement technique for inline inspection (ILI) for piggable pipelines. SCCDA is a continuous improvement process that identifies and addresses locations where SCC has occurred, is occurring, or might occur.
SCCDA, ILI, and Hydrostatic Testing (HT) are primary inspection tools, acknowledged globally as approved pipeline integrity inspection techniques for the assessment of SCC. These techniques have advantages and disadvantages, and each reflect a different, unique aspect of the overall integrity of pipelines. Therefore, an integrated approach, that would combine ILI and SCCDA indirect inspection techniques, would provide pipeline operators with a comprehensive integrity management program (IMP) for SCC.
An Integrated approach involves the use of ILI (Magnetic Flux Leakage, MFL; Electromagnetic Acoustic Transducer, EMAT), SCCDA Indirect Inspection Tools (Cathodic Protection Close Interval Survey, CP CIPS; Direct Current Voltage Gradient, DCVG; Alternating Current Voltage Gradient, ACVG), and Large Standoff Magnetometry (LSM) Screening Tool to assess susceptible locations to SCC.
This paper shows the benefits of an integrated approach and how the correlation of inline and aboveground pipeline integrity data ensures that SCC threats are confidently identified and mitigated. This paper also confirms that relying on only a single tool out of the integrity toolbox is not an effective means of managing risk of exposure to SCC. Recent advances and several SCCDA case studies are presented.
SCCDA, I LI, and HT are three inspection methods for the assessment of SCC. These techniques have merits and demerits, and each reflect a unique aspect of the overall integrity of pipelines. SCCDA is complementary with these two inspection methods and can be used to prioritize a pipeline system for ILI or HT if significant and extensive SCC is found.