Method:

Induce a high frequency magnetic field in the tube under test.  Eddy current will follow and uniform field will be modified as defects pass by.

Application:

In any electrical conductive material weld line testing on (but not DSA) on-line.

Product:

Normally non-ferrous products (aluminum titanium etc).  Can test steel materials

when used with a magnetic saturator.  Best suited to small diameter and thin wall

tubing, under 2” (50mm) diameter and under 3/16” (4mm) wall thickness.

Advantages:

High speed testing, usually completely non-contact with the product.  Can test at elevated temperatures.

Disadvantages:

Very sensitive to changes in geometry, conductivity and other phenomena not

related to defects. Often insensitive to long continuous defects. Sensitivity

diminishes rapidly with depth of defect.  Difficult to calibrate and to relate defect

severity to indications from instrument.  Although it is frequently used to test magnetic

material with a saturator, it is better suited to non-ferrous material.