Skype: eds-ltd

1 Abdullah Alisha Str., Bugulma
423236, Tatarstan Russia

Opening hours: Mon-Fri 8:00-16:00 (GMT+3)
Lunch break: 12:00-13:30 (GMT+3)

The Magnetometer Survey Method

We present a new nondestructive method for pipeline diagnostic–a magnetometer survey method.

The basis of the method is comparison of the pipe’s magnetic field with the Earth’s magnetic field and detection of magnetic anomalies, or magnetic field perturbations, which are caused by pipe defects: corrosion spots, corrosion pits, weld defects, burring, and indentations. The shape and the extent of magnetic perturbations make it possible to determine with rather high confidence the type and the severity of defect.

All works are performed on the land surface and do not call for any special prestarting procedures. All that has to be done is to determine the pipeline axis and crossing with other lines.

Once the axis and crossing locations have been determined, the pipeline is scanned with the magnetometric scanner to determine anomalies pointing to pipe defects. Then, excavation exposes the pipeline, and non-destructive testing is run.

So, using the above diagnostics technique, we can significantly increase the quality and reliability of diagnostic operations for the following reasons:

  •  Reliability of information, obtained using this diagnostics method, is increasing;
  • Digging is carried out only in defective points;
  • Volume of digging works is reduced, which is important for rather new pipelines, as insulation coating is broken to a lesser degree, and risk of pipe damage by excavation equipment is decreasing.

Besides the equipment, we have developed presently "Procedure of continuous diagnostics of oil pipelines using magnetometer survey". In June 17, 2005 it was approved by the Board for Technological and Ecological Supervision of Russian Federation.

Engineering data of the equipment being used (magnetometer):

1. Value to be measured

  •  Module of magnetic induction or gradient of magnetic induction module.

2. Type of magnetometer:

  •  Proton magnetometer on Overhauzer effect

3. Range of measurement:

  •  From 20000 nanotesla to 100000 nanotesla, with error of 0.1 nanotesla

4. Types of detected defects:

  •  Corrosion pits, spots;
  • Defects of weld joints;
  • Fractures;
  • Dents;
  • Burrs;
  • Changes of pipe wall thickness;
  • Potentially dangerous sections, being under stress.

5. Minimum length of detected defects:

  •  From 2 mm (fractures, defects of weld joints, pits)

6. Depth of detected defects:

  •  Not less than 10% of pipe wall thickness

7. Errors of determination:

  •  Lengths of fractures up to 10%
  • Depths of surface fractures up to 10%
  • Thinning of wall up to 10%

8. Deviation from pipeline centerline during inspection:

  •  Not more than 1.5 m (depending on working pressure)

9. Rate of control:

  •  Up to 2 m/sec

10. Diameters of being inspected pipelines:

  •  56 ÷ 530 мм.