Applus + in Australia has successfully repaired a pipe that was damaged by corrosion after only five years of operation. The client requested that Applus + evaluate the general condition of the pipe. That evaluation found leaks in the external wall as a result of corrosion, with 60% potential loss of wall thickness.
The project included both the proposal and the preparation of an approach to inspect and measure the areas exposed to pitting as a result of external corrosion. The inspection also aimed to control hard-to-reach areas below the earth's surface.
Applus+ specialists in Perth developed a fast and efficient inspection methodology that satisfied all requirements. It was based on two technologies. Firstly, the Creaform 3D scanner modelled the entire section of pipe being inspected, using high-powered lasers together with powerful inspection and modelling software, PipeScan.
Guided wave testing was then carried out. These are a form of long-range ultrasonic testing (UT) designed to screen large areas and inaccessible areas of piping. Guided wave testing finds areas of potential wall loss in piping and provides an estimate of that wall loss based on cross-sectional change vs circumference. A pioneering approach, the test was carried out in close collaboration with Guided Ultrasonics Ltd (GUL), the company that manufactures, trains and develops the technique. All inspections were carried out successfully from excavations controlled by confined space (CSE) procedures and requirements.
In general, for wall thickness loss of less than 46% on 7" production pipelines, a thermoplastic sprayable corrosion-inhibiting barrier coating (CIST) system is needed. For wall thickness loss of more than 46%, however, a composite wrapping repair system is needed to provide a high-strength layer around the steel casing. In this case, as the results showed a 60% loss, Applus+ put the second fix in place. The system was successfully applied, leaving the client very satisfied.