Pipeline Efficiency Testing Made Easy

Helling’s (Germany) KMU 8/42 Cross Yoke Magnetic Particle Inspection unit can locate  superficial and sub-surface defects quickly and efficiently with just one magnetisation test. It is reliable enough to perform this test during the production of the pipework, which is a trully remarkable level of speed and efficiency.

 The KMU 8/42 consists of two alternating current yokes disposed crosswise with pole spacing of 170 mm. They are fed by 2 equal alternating currents with 90° phase shift, which results in a rotating magnetisation vector, whose field strength is equal in all directions. This magnetisation technique enables the detection of discontinuities of every orientation. In practice it means: simultaneous indication of longitudinal, transverse and oblique cracks in the course of only one operation.

To detect superficial defects (and those near the surface) with any spatial orientation at a test area during one magnetisation procedure!

Remarkable enhancement of the test speed, e.g. at weld tests during production of pipework!

Therefor, two crosswise combined alternating current yokes are powered with equal currents which are phase-shifted by 90°. Thus, a rotating magnetising vector is generated whose field strength is equal in any direction. Therefore the probability of detection is equal in any case, independent of the orientation of the indication.

The magnetic field is induced to the surface of the test item over a small air gap. This is kept constant over long test paths by bottom rollers fixed to the four poles, which can be re-adjusted if required. The safety isolating transformer (3x42 V AC; at the primary winding 3x400 V AC) and the cross yoke are connected by a highly flexible cable of 5m in length. This construction facilitates convenient re-positioning of the yoke over the tested surface.

Once the four yoke poles are attached to the surface to be tested, the cross yoke yields a tangential field strength of 32 A/cm and a lifting force of 300 N. At an air gap of 5mm the tangential field strength will be not less than 22 A/cm.