NOPIG TECHNOLOGY AS AN ALTERNATIVE

The NoPig inspection technology is based on the measurement and evaluation of the resulting magnetic field on the application of an electric current to a buried steel pipeline. Interpretation is in relation to the loss of metal is not an absolute wall thickness. The system NoPig measures on the surface, the magnetic flux density of the magnetic field induced when a current is a buried steel pipeline. The review on the current pipeline is the superposition of the selected frequencies between 8.5 Hz and 630 Hz to 8.5 Hz component fills the entire cross-section
The pipe, while the component at 630 Hz flows only in the outer edge of the cross section. This is known as the skin effect. The magnetic field induces a current in a pipe without defects is concentric to the axis of the tube. The technology uses NoPig the effect that the skin is a frequency-shift in the external magnetic fields on a defect in the tube wall. The NoPig labour resources in the field is divided into three modules:
-The current source module (powered by a small generator)creates the necessary power at the selected frequencies.
-The sensor array, which is a board with the hand of 24 magnetic sensors in 4 rows, each with 6 sensors.
-The acquisition and storage module, which is backpack or  trolley mounted. This device is indicated by cable to the sensor array and records signals from the sensor array. It features an integrated notebook displays, the relevant information for the operation of the system.

Magnetic field strengths
The weber (WB) is the unit of magnetic flux. The Tesla (T) is the unit of magnetic flux density, 1T WB = 1 / sqm. The horizontal component of the Earth's geomagnetic field has a magnetic flux density, between zero and about 25 μ T (microtesla). It is this horizontal component that is significant for the comparison with the NoPig magnetic field. The NoPig magnetic field generated by the current test NoPig, has a magnetic flux density, which is in the order of 1 μ T on the frequencies of NoPig. The field strength at the surface, ie on the sensor array, is inversely proportional to that depth coverage of the pipeline under the surface. (That is to say that the deeper the tube of the weaker the signal on the surface) The variation of the magnetic flux density of the horizontal component of the Earth's geomagnetic field is normally no more than the range of a few dozen picotesla. To ensure that these fluctuations in the magnitude of 100,000 times smaller than the area of the NoPig. The change in magnetic flux density of the field NoPig caused by a reference defect is about 1 nanotesla. That is to say that the changes caused by a reference defect is about 25 times greater than the fluctuation in the Earth's magnetic field and, as such, can be detected. Compare 40 picotesla to 1 nanotesla.