Ultrasonic Tandem Testing Technique
Ultrasonic tandem testing uses two separate probes to detect deep-lying, vertically oriented internal flaws in metals. The backwall reflects the ultrasonic wave and picks up unfavorably oriented reflectors.
Physical-Chemical Working Principle
The technique uses two ultrasonic probes: a transmitter that emits waves and a receiver that detects the returning waves. The back wall of the test object reflects the waves, so even fine surface flaws or internal cracks can be detected.
Metallurgical Relevance & Welding Risks
This technique is especially useful for inspecting weld surfaces and materials with complex geometry. It can detect deep cracks, porosity, or corrosion susceptibility that other test methods might miss. However, an improperly calibrated receiver or faulty reflection from the back wall can lead to false results.
Workshop Practice & Procedures
To successfully use the Tandem ultrasonic testing technique, follow these steps:
1. Calibrate the probes: Make sure both probes are correctly calibrated and the waves are properly received by the receiver.
2. Position the probes: Place the transmitter on the surface to be tested and the receiver on the back wall of the test object so the waves are reflected properly.
3. Run the test: Perform the ultrasonic test and carefully analyze the results for any anomalies or missing reflections.
4. Write the report: Document all found defects and give recommendations for further testing or repair.