Worcester NDT- Corrosion Testing

Thickness and Corrosion Testing.

Through Coating Testing.

Metals, plastics, ceramics, glass or virtually any other material which conducts ultrasound can be accurately gauged over a wide range of thicknesses. One of the most outstanding uses for ultrasound is to assess material thinning due to corrosion or erosion, including many types of pitting action.

A Range of applications include:
Heat exchanger tubing, pressure vessels, machined parts, flanges, bridges, airframes, aircraft windows, glass plate, vessels, plastic shapes and pipe and containers, ship hulls/decking, storage tanks, bulkheads, boilers, axles, wheels, rails, steam lines, castings, pipes/tubing, plates/slabs/blooms casings, billets/bars, extrusions, forgings, beams/struts and many more.

Many requiring testing will have surface coatings of one form or another, the most common being paint. If the correct technique is not used a reading that includes the coating thickness will be produced. If the coating varies in thickness across the test piece, a false indication of material thickness or corrosion can be obtained. The use of multi bounce echo testing can ignore the coating and give a true indication of the material thickness. At Worcester NDT we only use multi bounce machines with data loggers to give accurate readings which can be stored and downloaded to a computer for future analysis.

Applications

Single Bounce Echo		Multi Bounce Echo

Ultrasonic Thickness Testers operate on a principle similar to sonar except at much higher speeds and frequencies. The probe's transmitter (T) sends a short pulse of ultrasound into the material. This pulse is reflected as an echo from the opposite surface of the material and returns to the probe receiver (R). The gauge measures the round trip time of the pulse, then compensates for the material's ultrasonic velocity and displays the thickness.		To eliminate the coating thickness, multi echo readings are taken. By measuring the time delay between any three consecutive back wall echoes, the time T1 (Coating Thickness) is ignored. The times of T2 and T3 are equal to the time that it takes to travel through the metal. Only by looking at three echoes can the measurements be automatically verified (where T2 = T3)