When evaluating the entire circumference of a test part at one time, which coil is used?

The use of an encircling coil is key when evaluating the entire circumference of a component in electromagnetic testing. This type of coil wraps around the test part, allowing for a comprehensive examination of its surface and detecting any surface or subsurface irregularities across its entire perimeter.

Encircling coils are particularly effective because they provide a uniform magnetic field coverage, ensuring that any flaws or changes in the material properties are identified during the testing process. This contrasts with other coil types, such as probe coils, which are typically designed for localized testing and do not assess the full circumference at once. The encircling coil's design makes it ideal for applications where a complete assessment of the part's integrity is required, ensuring that no area is left unexamined.