PipeMonit* and UltraMonit† are well established corrosion monitoring tools based on ultrasound, and can be used for monitoring pipelines both subsea and topside/onshore. The tools are non-invasive and provides real-time and online wall thickness data on subsea spools, elbows, pipelines and pipes. The ultrasound transducers measure wall thickness as a function of time and provide high resolution data on material wall loss. The sensors are installed directly on the pipe outer wall, or on top of the weld seam. This way the tools can monitor preferential corrosion and corrosion in Heat Affected Zones (HAZ).
Preferential weld corrosion has high attention as this can be a serious issue for oil and gas industry. Sensorlink has developed a tool for monitoring the preferential weld corrosion by using the ultrasonic technique. A matrix of ultrasound transducers is mounted on the outside of the pipe where the center of the transducer is located at the center of the weld. This way one can follow the wall thickness trends on both the weld and the HAZ zone with high resolution.
In this paper field data from preferential weld corrosion monitoring is presented, and compared with other techniques used for monitoring.
Key words: corrosion monitoring, weld monitoring, integrity management