Putting the pieces together

The morphology of Stress Corrosion Cracking (SCC) is highly variable, and there may be many other features present in the pipe body and seam weld which are not a result of environmental cracking but create similar signals in inspection data. These challenges make it difficult to reliably identify the different feature types based on a single source of inspection data. This in turn creates significant uncertainties as to how to best manage the future integrity of a pipeline subject to SCC.

When SCC is discovered in a pipeline system, industry-based practice requires further investigation in the form of hydrostatic testing, inline inspection, or direct assessment. Hydrostatic testing often requires significant downtime, which is often impractical for many operators. That is why a range of multi-disciplinary elements is needed to effectively manage these threats.

ROSEN’s reasoned and systematic approach, that focusses efforts on the critical issues and locations of features, is overviewed in the Crack Management Framework.

In this approach, all available data is integrated and utilized to fully understand the probable cause and morphology of any SCC, and to evaluate the sizes of these critical defects in order to ensure safe operation. Since not all parts of the pipeline have the same susceptibility to SCC, dividing the pipeline into segments of similar SCC risk is required to help focus the ILI data evaluation effort and optimize future integrity management activity. Effective segmentation requires the integration of extensive pipeline information, including original pipeline design data, pipeline coating data, construction methods, terrain representations such as those from Google Earth™, soil data, and rainfall records. This information is then combined with the inline inspection reports; since SCC may be linked to stress raisers such as dents, areas of corrosion, and locations with bending strain. With a thorough understanding of the issues and constraints, future integrity management programs are enabled and comprehensive asset care can be achieved.