Engineers working with magnetic particles

A certified weld inspector – as mentioned in our previous blog on the importance of an outsourced weld inspector – is essential for any company in an industry that requires the use of heavy machinery, such as cranes or forklifts.

Not only are weld inspections important for the safety of employees, the efficiency of machinery and for liability reasons, but they are also a fundamental business practice to meet industry standards and regulations. 

Weld inspections, which should be carried out by highly-trained and experienced weld inspectors, help to identify both structural and non-structural defects to ensure the safety and maintenance of the equipment.

Magnetic particle inspection is a non-destructive test used by experienced inspectors to find potential or existing defects. This method uses a magnet, known in the industry as a “yoke”, to find fine cracks and verify defects that were spotted by an inspector visually.

Here, Sparta Engineering explains the different levels of sensitivity used in magnetic particle inspection:

Dry magnetic particles

Dry magnetic particles are produced to include a range of particle sizes, with fine particles measuring around 50mm (0.002 inches) – around three times smaller in diameter and more than 20 times lighter than the coarse particles, which are 150mmm or 0.006 inches in size.

This size difference changes the levels of sensitivity of the particles, but dry particles must be made of both fine and coarse particles if they are to be put into practice. The dry particle method provides inspectors with improved sensitivity for the detection of subsurface flaws.

Dry magnetic particles are typically available in red, black, gray, yellow and several other colours that create a high level of contrast between the particles and the machinery being inspected. This makes it easier for the inspector to distinguish any possible defects.

Wet magnetic particles

Wet magnetic particles, on the other hand, provide inspectors with improved sensitivity for the detection of very fine surface flaws. The wet method is generally more sensitive than the dry method, due to the particles being supplied in a wet suspension such as water or oil.

Due to this wet suspension, the particles have more mobility – meaning smaller particles can be used to inspect for potential defects in the machines structure. Also, unlike dry magnetic particles, fluorescent particles are available for the wet method.

Fluorescent particles are coated with pigments that fluoresce when exposed to an ultraviolet light. These particles, which often come in green or yellow, help to find extremely fine cracks which are rarely visible to the naked eye.

Why Sparta Engineering?

These methods require an experienced weld inspector, and that’s why here at Sparta Engineering we advise you to outsource your weld inspection requirements to a professional and certified weld inspector with multiple years in the industry.

Our inspectors have a long history of working in the weld inspection industry, and are experienced in using magnetic particle inspection methods as well as using their experience to find frequent and repeated issues. This experience means we can resolve issues quickly and to the highest possible standards, delivering cost savings and helping you meet industry regulations.

Want to find out more? Contact us today.