Steel Rail Magnetic Particle Testing Technology
In recent years, the use of steel rail magnetic particle testing (MT) technology has become increasingly popular to complement the dated standard visual inspection and radiography methods used in the metal fabricating industry. Until the 1950’s non destruct testing methods were not used in rail inspection, leaving operators to rely solely on visual test such as performing hammer strikes to detect surface and subsurface flaws. This was replaced by MT in the late 1950’s where industry now saw the benefit’s of utilizing non destructive techniques in steel rail transport.
MT techniques apply magnets (or electro-magnets) in different directions to the rail and then passing magnetic particles which are applied with a tank onto the rails surface. The particles are attracted to areas of discontinuity and flaws, accordingly, these are visible on the rails surface due to the magnetic lines of flux being distorted. Many different materials can be used to move the magnetic particle, including water, oil and kerosene, which is normally based on the user. Oil based particle systems are generally cheaper than water based particle systems, however, the use of water based particles can be beneficial in that the process can be used in wet or humid conditions. Any material used to disperse the particle must not cause rust or other corrosive effects on the rail, or damage the adhesive or bond used in the weld.
When carrying out Magnetic Particle Tests, many pieces of equipment are required. These include a power source, a control unit, our electrode cables and a carrying case. The power supply will be used to provide the current needed to magnetize the rail. The control unit contains the necessary controls required by the operator and will also have a timer for pre-set cleaning cycles. On completion of the inspection the control unit will print out the results. The electrode cables send current from the power supply to the magnetizer. And the carrying case is used to transport all these items between tests.
A large advantage with carrying out MT inspections is that its portable and requires minimal manpower, meaning that more inspections can be conducted in a given timeframe. It is also highly accurate, providing detailed results. This helps to reduce the risk of structural failures, and costs associated with unnecessary repairs and replacement.
It is important to note that the success of any Magnetic Particle Test is largely determined by the competence of the operator. If an operator is unfamiliar with the process they are likely to miss or misinterpret defects. This can be mitigated by ensuring that the operator is trained in working with Magnetic Particles Test and that they carry out regular checks and maintenance of the equipment.
Overall, the use of Magnetic Particle Testing has revolutionized the inspection process within the metal fabricating industry. Not only is it an accurate and reliable method of inspecting steel rails, but it is also cost effective, as it requires minimal manpower and no need for specialist tools. With the correct training and maintenance of related equipment, it can be an invaluable asset in ascertaining the rail’s safety.
