Penetration testing PT
The penetration method is one of the most widespread methods of non-destructive testing. It has been known for over 100 years. It allows to detect open discontinuities to surfaces in ferromagnetic, non-ferromagnetic materials as well as non-metallic (e.g. ceramic) materials. It is often used to test non-magnetic elements made of aluminum or austenitic alloys.
Penetration tests belong to the surface test group. Due to the fact that the surface of structural objects belongs to particularly endangered zones, such tests constitute an important diagnostic tool for the safety of structures. Such tests are carried out at the production stage, or during inspection in operating conditions. The penetration method uses the phenomenon of liquid penetration (penetrant with appropriate properties) into the material.
After the appropriate time, the excess of the penetrant is removed from the test surface and so-called developer applied, which task is to pull out the penetrant from the discontinuity. The method requires very careful preparation of the test surface and is quite time-consuming. The advantages, in turn, include the possibility of testing a wide variety of materials. There is also the possibility of performing tests in fluorescence technique, which increases the sensitivity of the test. Penetration testing can also be used in some cases for leak testing.