Magnetic sensors detect corrosion by analyzing variations in the magnetic field of the pipeline's metal.

Ultrasonic testing pigs detect corrosion by examining vibrations in the walls of the pipeline.

The primary purpose of an MFL tool is to detect corrosion in a pipeline.

Although primarily used to detect corrosion, MFL tools can also be used to detect features that they were not originally designed to identify.

The accident was blamed on a failure to detect corrosion during inspection, with the allowable time between inspections and maintenance being exceeded.

But with further advances, the technique may be useful for detecting hidden corrosion in ship hulls, oil platform legs and pipe welds.

Ultrasonic testing and the use of "corrosion coupons" are also used to detect corrosion.

More than a month later BP sent a smart pig through its eastern pipelines, detecting extensive corrosion at several places and another small spill.

Skandinavisk Tilsynskontor investigators detected corrosion inside the actuator on 25 of 27 aircraft they checked.

Also, recently, wireless sensors, totaling 663, have been installed on South Korea's Jindo Bridge to detect structural cracks and corrosion.