Magnetic particle testing – Theoretical and regulatory aspects

Introduced in 1922, magnetic particle testing is constantly being developed to increase the probability of detecting discontinuities, and to improve health, safety and environmental protection conditions. Magnetic particle testing detection media, accessories and equipment are constantly being improved to achieve the highest levels of performance, while taking into account operators' concerns in terms of ergonomics.

Magnetic particle testing (MT) is the best practice non-destructive testing (NDT), used to detect and locate surface and underlying (near-surface) discontinuities in ferromagnetic alloys.

It is used in all industrial sectors, virtually anywhere, including underwater, on site or in the workshop, in manufacturing or maintenance. Like all NDT methods, MT has its own limitations.

Despite its undeniable advantages, MT does not always enjoy a very good image. It suffers in comparison with other, more recent NDT methods, such as ultrasonic testing and eddy current testing, which are often complementary to it, but which give a more noble image and are less painful for operators. Two of the criticisms often levelled at MT are the use of chemicals and the exposure of operators to ultraviolet (UV-A) radiation (or actinic blue light) and magnetic fields. However, if regulations on conditions of use and effluent treatment are followed, operators' health and the environment are protected, and MT is still a reliable, fast and cost-effective NDT method for inspecting parts and structures for safety.

This article deals with the theoretical and regulatory aspects of magnetic particle testing. It is particularly aimed at experienced users and designers of checking fixtures.