Penetration process
The penetrant method is a method for non-destructive testing of materials . It is used to indicate defects close to the surface , such as pores , cracks , defects in connection, overlaps and folds that are open to the surface . The procedure is standardized according to EN 571 and EN ISO 3452.
Procedure
After cleaning the surface, the penetrant, a strictly named liquid , is applied to the area to be tested. This liquid penetrates into existing cracks or pores. After a while, the penetrant will be rinsed from the surface. This is done with water or with a hydrocarbon-based cleaner with the help of lint-free cloths.
The penetrant remains in any cracks that may be present. If you now apply the developer, the remains of the strongly contrasting colored penetrant become visible on the surface over time. When the developer dries, it attracts the color as a powder when dry. The developer can be a liquid that is brushed on or sprayed on with spray cans or spray guns. This liquid can be water-based or solvent-based. In the case of a water-based developer, the component must be dried in an oven, or it is applied directly in powder form or dusted on using an electrostatic charge. The latter happens in closed chambers and increases the accuracy, since no solvent is necessary, which can wash out the displays.
In some cases, the workpiece is also viewed under UV light, which increases the display sensitivity. The method can be used for a number of materials and workpieces. It is not necessary for the test item to be magnetized.
Product families for penetrant testing systems, extract from DIN EN ISO 3452-2
The method used depends on the desired requirements for the sensitivity for finding displays as well as for environmental protection and work safety. The quantity of test pieces also plays a role.
| Penetrant | Intermediate cleaner | developer | |||
|---|---|---|---|---|---|
| Type | designation | Procedure | designation | Art | designation |
| I. | Fluorescent penetrant test equipment | A. | water | a | Dry developer |
| II | Dye penetrant testing agent | B. | Lipophilic emulsifier | b | Water-based wet developer, water-soluble |
| c | Water-based wet developer, suspension | ||||
| III | Penetrant for two possible applications (fluorescent dye penetrant test) |
C. | Solvent (liquid) - Class 1 contains halogen - Class 2 does not contain halogen - Class 3 for special purposes |
d | Solvent-based wet developer (non-aqueous for type I) |
| D. | Hydrophilic emulsifier | e | Solvent-based wet developer (non-aqueous for type II and type III) | ||
| E. | Removable with water and solvents | f | for special purposes e.g. B. Peelable Developer | ||
By far the most frequently used method is (II) III E e. It is suitable for almost all areas of application and forms the smallest test scope. It is therefore used for field operations and quick individual tests. Most of the penetrant testing agents available on the market have a UV- active or fluorescent substance added to them. With certain penetration methods, the penetrant must be re-emulsified when it is washed off in order to dissolve the oil-containing penetrant. The emulsifier is usually added to modern penetrants. The entire application range with all special variants is between −10 ° C and 250 ° C, the general range between 10 ° C and 50 ° C.
The storage and transport of the test equipment is subject to the Ordinance on Hazardous Substances and the relevant GGVS / ADR regulations.
application
The penetration process is mainly used for metallic materials, but can be used for all non- porous materials. It can be used with little effort even under construction site conditions. The effects of grease or graphite can impair the results as the crack becomes clogged. The area to be tested must always be free of rust, scale and any coatings such as paint or fats and oils.