What is a common non-destructive test for detecting near-surface weld flaws?

Magnetic particle inspection is a prevalent non-destructive testing method specifically designed to detect surface and near-surface discontinuities such as weld flaws. This technique utilizes magnetic fields and fine magnetic particles, which are applied to the surface of the material under inspection. When the magnetic field is induced, any defects present will disrupt the field and create a leakage field, which causes the magnetic particles to accumulate at the location of the flaws. This contrast allows for easy visualization of cracks, porosity, or other defects, making it highly effective for weld inspections in various applications.

Other methods listed, while useful in different contexts, are not as directly suited for identifying near-surface weld flaws. Visual inspection depends heavily on the inspector's experience and may miss flaws that are not visually apparent. Hydrostatic testing is primarily used to check for leaks in pressure vessels and pipelines rather than weld integrity specifically. Radiographic testing, although effective for a variety of defects, primarily detects internal flaws rather than those that are specifically near the surface. Each of these methods has its strengths, but magnetic particle inspection stands out for the specific purpose of assessing welds for surface-related issues.