Which testing method requires access to both sides of the material?

Radiography testing requires access to both sides of the material because it involves the use of X-rays or gamma rays to examine the internal structure of a component. During this process, radiation is directed through the material and captured on a detector or film on the opposite side. Because the radiation must penetrate the entire thickness of the material in order to reveal any internal flaws, both sides need to be accessible to perform the testing effectively.

In contrast, other methods like magnetic particle testing, eddy current testing, and ultrasonic testing do not necessitate access to both sides. Magnetic particle testing can be conducted from one side if the surface is magnetized. Eddy current testing is surface-dependent and typically does not require access to the reverse side. Ultrasonic testing generally uses a transducer on one side to send sound waves through the material and analyze the reflected waves, which is also feasible from one side. Thus, radiography is distinct in that it specifically mandates exposure from both sides to achieve accurate results.