The process consists in applying a colored or fluorescent penetrating liquid to the surface under study, which penetrates into any imperfections that may exist due to the capillarity phenomenon. After a certain amount of time, the excess liquid is removed and a coat of developer is applied, which absorbs the liquid trapped in the imperfections, making their outline apparent over the developer coat.


PROCEDURE

ASTM E165-02. Standard Test Method for Liquid Penetrant Examination.

 

  1. Preparation and cleaning: Carefully clean the surface to be inspected to get rid of any paint, oil, grease and other contaminant residues.
     

  2. Penetrant application: The penetrant is applied by dipping, spraying, brushing or pouring the liquid on the piece, to cover the area that will be inspected. It is left on the surface for 10 to 15 minutes.
     

  3. Removal of excess penetrant: You need to remove and clean the excess penetrant left only on the surface, taking care not to extract the penetrant that seeped-through the imperfections.
     

  4. Developer application: A thin layer is applied on the surface to be inspected, to reveal the location of the defect. It is basically a white-powder chemical product of inert components, with powerful absorbency qualities. It is left on the surface from 10 to 15 minutes.

     

Penetrant application

Developer application



ACCEPTANCE CRITERIA

 

This standard of acceptance should be used, unless a more restrictive standard is specified for specific materials or other applications. All surfaces to be examined must be free of:
 

  1. Relevant linear indications.
     

  2. Relevant rounded indications greater than 5mm.
     

  3. Four or more relevant rounded indications in a line, separated by 1.5mm or less between both edges.
ADVANTAGES
 		 DISADVANTAGES
 

  • It is relatively easy to apply.

  • It is inexpensive.

  • It detects a wide range of imperfections, regardless of the piece´s configuration or orientation.

  • It does not damage the piece.

  • You get immediate results.

  • It only detects superficial defects.

  • The surface to be inspected must be clean and free of any coatings.

 

 

 

 


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