What is a major danger of sandblasting surfaces before penetrant testing?

Sandblasting surfaces before penetrant testing can indeed lead to the issue of discontinuities being peened over and closed. This process uses high-velocity particles to clean surfaces, which can inadvertently smooth over small defects or cracks on the surface of a material. When these discontinuities are peened over, they may not be detected during penetrant testing because the penetrant may not be able to penetrate these areas effectively.

As a result, critical flaws within the material can remain hidden, leading to potential safety hazards if the material is subject to stress or loads later on. This is particularly significant in applications where structural integrity is crucial, such as in aerospace or heavy machinery. The risk of undetected flaws compromises the reliability of the testing process and can have serious implications for the performance of the component.

Understanding the impact of surface preparation techniques, like sandblasting, is essential in ensuring the effectiveness of subsequent non-destructive testing methods like penetrant testing. Thus, careful consideration must be given to the choice of surface treatment before conducting such tests.