Gating system on ultrasonic tester - uses first and second echos from far side of test piece to set fault test gate

摘要

The ultrasonic testing system is used for steel sheets or plates. A test impulse (1) is produced, and there is a time gate (3) during which an echo (7) is taken to be due to a fault in the steel sheet under test. There is a strong echo (2) from the far side of the sheet. This falls in a second time gate (4) and does not register as a fault. A second echo (8) is received from the fault. This does not fall in any time gate. The second echo (6) from the far side of the sheet falls in a third time gate (5).