Dye Penetrant Inspection (DPI) also called as Liquid Penetrant Inspection is an efficient, economical and widely used non destructive test method to detect surface-breaking discontinuities in all non-porous materials.
Penetrant test is based upon the principles of capillary action where liquid penetrates into a cavity, and is performed by cleaning the test surface thoroughly, applying colored or fluorescent penetrant, allowing penetration time, removal of excess penetrant followed by application of developer ( dry or liquid form).
1. The bottom discharge appears to be in good condition. However, you will not know unless you perform a Non-Destructive Test (NDT)
2. The Inspector added Dye Penetrant to inspect for surface cracking on and near the weld
3. After 15 minutes the inspector cleans the area of the dye and adds a developer to the area tested; each red dot represents an indication or a crack.
4. The discharge nozzle was connected to a diaphragm pump, this lead to mechanical fatigue of the weld. A closer look reveals linear cracking and porosity.
5. Cracking and porosity is apparent along the entire weld seam
6. Since the inspection took place during a plan shutdown the client was able to repair the weld immediately after the inspection. Because of the thorough inspection the client did not have an unplanned failure that would lead to a loss of product and loss of production time.