In order to detect pipeline damage or weakness, pipes are regularly examined with inspection tools. As it travels through the pipeline, the inspection tool detects the present state of defects and potential hazardous areas. The results are recorded in an internal memory unit.
During that process, marker magnets serve as reference points, being detected by the in-line inspection tool for calibration purposes.
The installation of marker magnets significantly reduces the cost and effort associated with benchmarking using above-ground marker (AGM) receivers. As AGMs, marker magnets are very effective in difficult driving/traffic conditions or when the inspection tool is traveling in the pipeline at a high speed. Since they are attached directly to the pipe, they require no maintenance or surveillance, which reduces the costs for inspections of long pipelines significantly. Furthermore, marker magnets remain in place upon survey completion and can be used for future inspections.