We are so few
As a Quality Assurance professional, it can seem that the world is against you. The problems we face are serious and can impact our test results negatively.
Contaminates that interfere with Liquid Penetrant testing are many, but some more severe than others.
Diffusa enjoys reducing capillary action in all liquid penetrants and may go unnoticed without proper system checks.
Water is a major contaminant that dilutes the liquid penetrant and reduces the liquid ability to seep into cracks and other open surface indications.
Excess water can get mixed in with emulsifiers and reduce the emulsifiers effectiveness. Water can cause clumping when it gets mixed in with dry developers as well.
NDT Villains like “Diffusa” cannot be overlooked and are always lurking around the corner to keep NDT inspectors on their toes.
System checks like those called out in ASTM E1417, Table 1 that range between Daily, Weekly, or Monthly which will keep the penetrant system working properly.
Water concentrations between 20 and 25% will cause most penetrants to gel and start to knock out the dyes and powders that are added to the penetrant to make them fluoresce. To be on the safe side most specifications require less than 5% water concentration in the penetrant solutions.
Gryme is a nasty villain that enjoys making the NDT world miserable and crosses other NDT methods but provides major issues to liquid penetrant testing.
Gryme may consist of many foreign materials like (grease, oil, solvents, soaps, dirt, dust, paint, and corrosion) which either block the surface opening or prevent the penetrant from performing as a penetrating fluid.
There are no specific industry standards to address this culprit. The best defense against this villain is to maintain a clean work space. Keeping a clean workspace can reduce contact trace resulting from the transfer of liquid penetrant from gloves and possible “Gryme” onto clean parts.
Don’t let Gryme get in your way and make your life more difficult than it already is by being diligent with your housekeeping.
An inspector needs all the time they can get to interpret test results without having to fight false calls and scrutiny by having a poor workspace.
Thanks to Peter Pelayo of McGean (Met-L-Check) for his input.