After 36 years of maintenance pipe fitting and fabrication for Du Pont I have a basic distrust for any dye penetrant metal testing around. Over the years we used many different systems and they all had different limitations which we sometimes found the hard way. X-ray or magna flux was just a better less prone to missing things type of method. I do know there are machines and methods to check linier cracks because we often found them and had to scrap large fabrications. Good Luck! Bill
zeebill live from the hills of West Virginia!