We have already gained a lot of information related to dye penetrant testing. Next, let’s focus on another important concept which is Magnetic Particle testing. But, before delving deeper into the topic, we must have some information fixed in our minds. These are the common yet essential terms related to magnetic particle testing.
This forms an essential part of the oil and gas courses for mechanical engineers.
There are a ton of terms related to magnetic field inspection and are very essential for oil and gas training courses online.
The terms that are frequently used in magnetic particle testing include:
1. Magnetic materials
Magnetic materials are those which are attracted by a magnet. These materials are known as paramagnetic materials. Whereas materials that are generally repelled by a magnetic field) are known as diamagnetic materials.
The subdivision of a paramagnetic material is termed ferromagnetic. Ferromagnetic materials are those substances that exhibit strong magnetism, where the direction of magnetism is in the same direction as the applied magnetic field.
2. Magnetic field
This is a vector field usually formed in the neighbourhood of a magnet, electric current, or changing electric field, in which magnetic forces are observable.
The magnetic field surrounding a bar magnet can be created by placing a piece of paper over a magnet and sprinkling the iron filings on the paper. The particles align themselves with the lines of magnetic force produced by the magnet.
3. Leakage Field
When a bar magnet is cracked, the north and south pole will form at each edge of the crack. The magnetic field spreads out on encountering a small air gap created by the crack because the air cannot support this amount of magnetic field per unit volume like the magnet. When the area spreads out, it appears to leak out of the material and, thus, is called a Flux Leakage Field.
4. Magnetic Flux
The lines of force in the magnetic circuit always form closed loops or paths. Hence a magnetic circuit is always closed. The total number of lines of magnetic force in a material is called magnetic flux. The strength of the flux is determined by the number of magnetic domains aligned within a material.
5. Magnetic flux density
The number of magnetic lines of force cutting through a plane of a given area at a right angle is known as the magnetic flux density. The flux density or magnetic induction has the “Tesla” as its unit.
6. Magnetic permeability
The magnetic permeability of a material is a measure of the material’s magnetization capability. This helps in determining how much magnetic flux the material can support, which will pass through it. Permeability is numerically equal to the ratio of flux density to a magnetizing force.
Retentivity can be described as a material’s ability to retain a certain amount of magnetization when the magnetizing field is removed after achieving saturation.
Coercivity is a reverse magnetizing force necessary to remove the residual magnetism to demagnetize a specimen.
There are a vast number of terminologies used in magnetic particle inspection. But, these are the most common and crucial ones. Keep your search mode on for similar terms and try to gain as much information as possible. To know detailed information about magnetic particle inspection, check our online course for piping engineering.
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