A full-coverage inspection was conducted of both pipelines internally to identify the pipeline conditions against identified threats and damage mechanisms. A number of priority parameters were set during the inspections to make sure the integrity approach was accurate.
Three inspection methods were used concurrently to determine the integrity of the pipes, with an emphasis on the external surfaces, since these are the areas most susceptible to corrosion:
- Visual inspection (VI):
- Pulse Eddy Current inspection (PEC)
- Ultrasonic Thickness Measurement (UTTM)
Fitness for Service Assessment
A fitness for service assessment was conducted on the reported anomalies to ensure the pipes are safe to continue in service. As well as carrying out the assessment according to a customised fitness-for-service (FFS) methodology, TWI also provided the client with an inspection strategy for the future, to ensure the most efficient use of resources and reduced inspection costs going forward.
The results of the assessment showed that the pipelines were generally in good condition, despite a few corrosion monitoring locations being identified for NDT inspection at recommended intervals. The conclusion of the results indicates that, while the CP system could not be checked, it is working efficiently on both pipelines and providing an acceptable level of protection and keeping the external corrosion rate below the theoretically expected rate. Inspection intervals of 5 years and 10 years were recommended for the pipelines.