Magnetic Flux Leakage
The flux-leakage probe method is used on ferrous, hot-rolled surfaces with round cross-sections. There are two main approaches to inspecting materials of this type:
- The AC field method - used for highly sensitive detection of longitudinal surface flaws, predominantly on hot-rolled bar stock.
- The DC field method - used for detection of external and internal flaws on hot-rolled tubes. Longitudinal flaws or transverse flaws are detected, depending on the magnetisation direction. API and ISO Standards describe the method.