Wall thickness measurement by ultrasonics

The tube is one of the most useful products of the fertile imagination of man. Liquids, gases and powdered solids may all be transported over long or short distances by the use of tubes, pipes and conduits and it is difficult to imagine many of the functions of modern life operating without their use. However no product is perfect and an attendant problem with the use of tubes is that their inner surface is entirely concealed and difficult to inspect yet it is here in most applications that corrosion and erosion take place, being revealed only by expensive and often catastrophic failure. The problem is exacerbated by the susceptibility of many tubing materials to inter‐granular attack resulting in localised pitting which may cause puncture and failure of the tube when most of the wall is still sound.