We perform dye penetrant testing on all bellows longitudinal seam welds before and after forming the bellows. The test is performed to insure there are no weld defects such as surface cracking or weld discontinuities. The weld surface is thoroughly cleaned and a red penetrant dye is applied to the surface of the weld and allowed to soak for a period of time. The dye is then removed and a white powder is sprayed on the weld surface that performs a blotting action. An indication of the dye with a white background characterizes the weld surface discontinuities of the bellows longitudinal seam weld. This testing before and after the bellows forming process ensures a sound quality bellows seam weld.
Procedure for Dye Penetrant Testing
Examples of Dye Penetrant Testing