Detecting Corrosion in Chemical Plant

There is an interesting similarity between the problems facing the maintenance engineer and those facing the medical practitioner. Corrosion, for instance, can be considered as a generic term for a variety of ‘ailments’ in factory plant. One may carry the analogy further and equate preventive medicine, which is one of the fundamental tenets of medical theory, with preventive maintenance, which is now rapidly gaining ground in engineering circles. As with certain human complaints, it is impossible to eliminate corrosion completely—what is important is to take the necessary remedial action before it has gone too far. The analogy extends even further: the engineer now has diagnostic tools comparable to the doctor's stethoscope. Ultrasonic waves are now used to measure the thickness of walls of which only one side is accessible. Such measurements are non‐destructive, safe, quick and accurate. This article describes an ultrasonic thickness gauge and its use in the chemical industry to check for corrosion without interfering with production.