Integrity assessments for external corrosion damage on an exposed pipeline are only as accurate as the methods used to quantify the extent and severity of the damage. Inaccuracies in measurement can lead to unnecessary repairs or non-conservative assessments.
This paper describes the development and use of the second-generation Laser Pipeline Inspection Tool (LPIT). The LPIT is used to reliably and efficiently measure and assess corrosion damage on external surfaces of exposed in-service pipeline segments. To overcome the limitations of the previous system, Mark II LPIT utilizes a spot laser sensor that allows scanning of up to 103 degrees of pipe circumference. The sensor is mounted on a magnetic-wheeled crawler, which permits scanning of unlimited lengths of pipe in any clock position with high acquisition rates. Furthermore, the system has the ability to auto-steer at all orientations about the pipe.
Typical pipeline characteristics such as dents, bends, bulges and welds formerly impeded corrosion measurement. New sophisticated software (CorrosionPro98) easily accommodates such features allowing the system to provide an accurate and precise measurement of corrosion. CorrosionPro98 software incorporates the RSTRENG analysis that is used to assess the significance of the damage from the data and calculate the predicted failure pressure. The LPIT system provides colour-coded contour maps of corroded areas.