Project Description

Strong Permanent Magnets for Oil & Gas Industry – Magnetic Flux Leakage

Magnetic flux leakage is a magnetic method that is used to detect corrosion and pitting in steel structures. As one of the nondestructive testing techniques, MFL is widely applied to the inspection of defects in oil and gas pipelines and aboveground storage tanks made of ferromagnetic material.

The basic principle is that a powerful magnet is used to magnetize the steel. At areas where there is corrosion or missing metal, the magnetic field leaks from the steel. Therefore MFL can detect corrosion by sensing magnetic leakage.

Magnetic Flux Leakage system is mainly composed of magnetizing device, yoke and sensor array. Permanent magnets are high magnetic energy product, small size, light weight and no external power required. So the magnetizing device usually uses permanent magnets.

What type of magnet is used on MFL in oil & gas industry?

Typical inspection designs use Neodymium Iron Boron magnets. NdFeB magnets are the strongest commercially available magnetic materials, both magnetically and structurally. Other applications may use other magnet materials including hard ferrite, AlNiCo magnet and smco magnet.

Ferrite magnets are the cheapest magnet, but the remanence is low. The remanence of Alnico magnet is high but coercivity is low. Rare earth permanent magnet (NdFeB and samarium cobalt) is expensive, but coercive force & remanence are high.

For different permanent magnets, the magnetic circuit design should be based on their magnetic properties. It should give full play to their advantages, so that the magnetic circuit achieves the optimal effect.

Regarding permanent magnet materials with high remanence and relatively small coercive force, it is advisable to use the long and thin magnets. In regard to the permanent magnet materials with low remanence and relatively large coercivity, it is advisable to use the short and thick magnets.

When the coercivity of the permanent magnets is determined and the magnetization effect cannot be satisfied, it can increase the size (general width and thickness) of the permanent magnets.

Manufacturer of Magnet for MFL

Common neodymium magnet grades are available in N38, N42, N45, and N50M. Sizes we made before include 40x20x10mm, 25x25x25mm, 40x25x10mm, 45x45x45mm and so on. We also produce segment, ring and cylinder magnet for MFL detectors.

China Magnets Source Material Limited has many years of experience in the production of permanent magnet for oil and gas industry. Our high quality magnet has been used for oil pipeline inspection in the Pacific Ocean. If you need any permanent magnet for MFL, please feel free to contact us.

We will answer your email shortly!