The client found significant pitting corrosion on their pipelines and requested Assistu to help assess these lines prior to reactivation. The timeline for reactivation was short so a solution and quick turnaround was requested. It was decided that the best approach would be to create pitting corrosion screening graphs to assist inspectors for evaluating the flaws on the fly. From the 6 pipelines that have been chosen for inspection, 4 separate defect screening graphs were completed to accommodate the different pipe sizes and thicknesses. The pipelines were several kilometres long so this saved a lot of time and reduced uncertainty among the inspectors. With several discussions with the client throughout the project, screening graphs were provided prior to inspections along with a procedure of how to use them.
When the inspections were completed, the flaws that did not pass the screening would be evaluated as part of the pipeline fitness for service (FFS) assessment.
Through discussions with the client and only when a course of action was agreed upon, the finalized report was provided about 2 weeks after. Assistu concluded that out of the 6 pipelines, 4 failed the FFS assessment and portions of the pipeline were required to be cut out and replaced.
Did you know? Screening blunt flaws, such as general metal loss, can be evaluated using API-579 / FFS-1 or ASME B31G.
The project was a success and the client was able to meet their deadline for reactivation.