Capillary pressure

October 2011

In December 2010 and January 2011, two readers from North America asked us almost the same question about the pattern of indications on Known Defects Standards (KDS) used in Penetrant Testing, during repeated tests.

A third question, on the same topic, made us write a paper published on our Website(*).

Some weeks ago, the two readers from North America sent us acknowledgments for our help, as this paper helped both to answer remarks by auditors about the different patterns shown by KDS used daily on PT process lines. Two auditors required that, not only the number of indications be the same as on the reference pictures, but also that the indications be identical.

After reading the explanation about the capillary pressure, after thoroughly looking at the questionnaires (which ask for detecting a certain number of defects, with no reference as to the size of the indications, or their aspect, or their pattern), the auditors came to the conclusion that the auditees met the requirements - at least on this point!

We are happy to have been of some help for users to pass successfully an audit - in fact, both had only very few minor non-conformances (NC), easily and quickly fixed.

Reference

(*)Patrick DUBOSC and Pierre CHEMIN, Capillary pressure and its surprising consequences on PT indications, Editorial – April 2011. On our Website:
http://www.ressuage-magnetoscopie-penetranttesting-magnetictesting-dpc.info/site/en/edito/edito-2011/53-avril-2011-pression-capillaire-et-ses-surprenantes-consequences-sur-les-indications-de-ressuage