Dye Penetration Testing
Dye penetration testing has been around for a long time. The premise behind the test uses 2 different spray-on materials that, when applied properly, make a crack in the steel visible. And it’s a pretty simple test to run once you know how.
We always try to keep a dye pen kit with us in our field offices when we are involved with bridge rehabilitation projects since, often-times, after deck removal, we find girder top flange conditions that need to be checked for cracks. I’ve successfully used the well-known & readily-available SpotCheck kit – We purchased a new kit specifically for this effort.
The process takes a few steps:
First, we cleaned the deformed areas with the cleaner to get rid of the dirt & weather-born debris on the steel. Dave & I were up in a manlift with nothing more than Windex and paper towels.
Next, we sprayed on the penetrant. The material is a highly viscous solvent that, essentially, is drawn into any cracks using the principle of capillary action (go get your basic engineer book out if you need to look that one up….).
The next process is the messy one: With latex gloves on and rags in our hands, we wiped off the excess penetrant off the surface. As the capillary action held the penetrant below the surface in the body of the crack, the surface wiping doesn’t effect or “pull out” the penetrant in the deeper crack.
The last step in the process is spraying-on what’s call the developer, which is a white compound that draws any dye penetrant out of the crack where it can be visually seen. Pretty cool stuff.
Dye Penetrant Inspection Procedure
This article provides you with a example dye penetrant inspection procedure. This procedure contains water washable process with both visible and fluorescent systems.
1.0 SCOPE
1.1 This procedure establishes the general requirements of Penetrant Testing of ferrous and non-ferrous components (essentially non-porous) and welds by Water Washable Process, Visible and Fluorescent Penetrant Systems and are to be followed by NDT personnel Third Party.
Fortunately for us, we did not find any cracking in our damaged areas. If there were cracks, we would see the deep purple dye lines within the white developer areas.
2.0 PURPOSE:
2.1 The requirements are intended to detect discontinuities that are open to test-surface and free from contaminants by interpreting the surface indications and evaluating them in accordance with the applicable referenced codes, standards or specifications by certified NDT personnel qualified in PT to Level II.
2.2 Customer’s approved specific Inspection/Evaluation manuals have also to be followed strictly, if available and applicable.
2.3 Any conflicts between any points of this procedure and the referenced documents or job specifications of customer shall be resolved (if given in writing) by the appointed ASNT NDT Level III or the Divisional Manager (NDT) or his authorised representative.
2.4 Where special circumstances require unique techniques of Penetrant Testing by Water Washable Process, specific technique sheets shall be attached as Annex: IV etc., with the written approval of NDT Level III.
Comments
Post a Comment