In-Line Inspection Tools for Crack Detection in Gas and Liquid Pipelines

The occurrence of stress corrosion cracking (SCC) has become a serious matter for many pipeline operators around the world. Advanced in-line inspection technology using nondestructive methods is considered the most promising approach to detect and size this kind of damage. Considerable progress has been achieved with the UltraScan CD (Crack Detection), a new generation of internal inspection device especially designed for the detection of axial crack-like defects in pipelines. Since its commercial introduction in October 1994, the crack detection tool has successfully inspected over 2,000 km of operating oil and gas pipelines. The inspection runs were followed by verification excavations at specific locations selected from the collected data. Comparison of the findings with corresponding verifications from excavations illustrate the sensitivity and reliability of the inspection concept and the ability of the tool to safely discriminate between injurious crack-like defects and different non-injurious reflectors such as e.g. inclusions. The performance has proved the tool to be a reliable internal inspection device for the detection and sizing of cracks (SCC, fatigue cracks and crack-like defects) in pipelines.