Calibration for MT

Other than the Gaussmeter, our company also have many other methods/equipments to calibrate our MT machine. However, we seldom use them as they are not very useful. For example, the Pie Indicator, which is supposed to indicate the field direction, is almost no use because the direct of field is quite clear in a MT machine (either longitudinal or circular).

If I need to choose one method for calibration, expect the artificial flaws, I like Ketos ring most. It is used to evaluate and compare the overall performance and sensitivity of the MT machine. We use central conductor and pass current through the hole of the ring. If minimum number of holes can be shown, the test result is acceptable. But we can only use DC or full-wave rectified AC to do the test. Also, we need to demagnetize the ring before test because residual may left in the ring.

I love to conduct NDT, because it makes me a detective in finding flaws.