The technique is based on the inverse magnetostrictive effect, magnetoelastic effect or Villari effect is the change of the magnetic susceptibility of a material when subjected to a mechanical stress.

 

1. The magnetoelastic effect itself is a change in induction in a ferromagnet located in an external magnetic field under the influence of mechanical loads;
2. Magneto-mechanical effect – a change in the vector of residual magnetization of a ferromagnetic product in the direction of maximum stress.
3. Magnetoplastic effect – the effect of the formation of domains and domain boundaries on clusters of dislocations in zones of stress concentration;
4. The effect of magnetic field scattering by structural and mechanical discontinuities under conditions of natural magnetization of the metal.

Local deviations of the magnetic field force from the average characteristics in the measurement range are called ANOMALIES. The main characteristics of the anomaly is its  SHAPE  and  AMPLITUDE.

Magnetic field ANOMALIES can be fixed and evaluated.
stress-deformed condition of metal used as an indication of the availability of various types metal defects.

Remote non-contact (from the surface of the earth) detection of pipeline sections with NDT anomalies, associated with defects of the base and welded metal of any nature and increased loads in real operating modes.

NON CONTACT MAGNETIC DIAGNOSTICS is applicable to steel pipelines of any purpose. The declared level of NDT anomaly detection (POD) is at least 75% (depending on the construction of the object) in the established range of mechanical stresses.

DETECTED:

1 – Defects of the metal of any nature, including technological defects, mechanical damage, internal or external surface corrosion, crack-like defects, including stress corrosion cracking, fatigue cracks, cold cracks in welds.

2 – Stress concentrators in areas of increased loads, in seismically active zones, in soils with low bearing capacity, with free sags, bends, landslides, sections with local or general loss of stability.