Penetrant testing under vacuum conditions
Capillary testing under vacuum conditions is a special dye penetrant inspection where the test medium is drawn into fine cracks by vacuum. This increases the detection reliability for hard-to-reach capillary systems.
Physico-chemical mechanism of action
Capillary testing under vacuum uses the physical phenomenon of capillary forces. Under reduced pressure, the test medium is drawn into fine cracks because of its surface tension. This allows precise penetration of the test medium into the deepest and narrowest capillary systems.
Metallurgical relevance & risks during welding
This method is particularly useful for checking weld areas where hermetic properties are important. It can detect cracks or bonding defects in the microstructure that are not visible with other methods. However, insufficient vacuum pressure can cause the test medium to not fully penetrate the cracks, compromising detection reliability.
Workshop practice & instructions
To perform a vacuum capillary test, a special device with a vacuum pump is used. The test medium (e.g., dye) is placed in a container and the pressure is reduced. The penetration time should follow the manufacturer's instructions to ensure optimal detection reliability.