Tech Tip: Indentifying the leak

 

Have you ever done a R&R on a converter, get it all the way done and get it to the leak checker only to find out it is leaking? On top of that, the leak is not coming from your weld! We use a very inexpensive way of checking for stress cracks and/or leaks before we go through all of that and you can too. You can purchase the test kit from your local welding supply house for under twenty dollars! Dye penetrant inspection (also called liquid penetrant inspection) is a widely applied and low cost inspection method used to locate surface breaking defects in nonporous metals. Dye penetrant will detect any defects, cracks, and leaks in new products as well as fatigue cracks on units out in the field.

Inspection steps; PreCleaning: The test surface is cleaned to remove any dirt, oil or grease (the washers in the converter industry will work fine). The end goal of this step is to have a clean, dry surface free of contamination. Application of Penetrant: The penetrant is applied to the surface of the item being tested. Allow the penetrant time to soak into any flaws. This generally takes fifteen to thirty minutes. Excess Penetrant Removal: Using a solvent remover and lint free cloth the excess penetrant can be removed. It is important not to spray the solvent on the test surface directly as it can remove the penetrant from the flaws. This process must be performed with care to assure the trapped penetrant is not removed from the real defects. Application of Developer: Now that the excess penetrant has been removed a white developer should be applied. The developer should for a semi-transparent, even coating on the surface. The developer draws the penetrant from the defects out onto the surface to form a visible indiction of defect. Any colored stains indicate the positions and types of defects on the surface. An inspection of the test surface should take place after a ten minute development time. This time delay allows blotting action to occur.


Ken Kelly
Transmission Specialties

– FoundĀ in July 2009 Newsletter