PT test panels: criteria for choosing ones for on-site use

July 2010

Having read the DPCNewsletter N°025 – June 2010: PT test panels: criteria for choosing ones for on-site use, one of our French readers, who works for a large prime in aerospace industry, sent us this message:

‘‘Reading this paper on test panels, I did not (or I failed to) see a sentence about the penetrant in opened tanks. In such a situation, the penetrant may become less sensitive; this could be a major reason to use test panels as those you described (PSM-5® or another one). I would like to know what you think on this topic if useful to you /your readers.”

Our answer:

‘‘As a matter of fact, our DPCNewsletter N°025 dealt only with the PT test panels used on-site, out of a process line, and not in a workshop, as we answered a question by a reader.

Applying penetrant by immersion can be performed almost only in a workshop. As for opened tank, it is always advisable to fit it with a lid to prevent or lower pollution, evaporation of some of the chemicals or any drop of water or other material. Keep in mind that the chemicals the most likely to evaporate are the hydrocarbons; this increases the dye concentration, making the penetrant more sensitive, though more difficult to remove from the surface. Today’s penetrants are less prone to evaporation, except in high ambient temperatures. Anyway, a lid is strongly recommended because of the other points.

Our March 2009 DPCNewsletter N°010, titled ‘‘Penetrant Testing: test panels/parts cleaning’’, displayed several test panels.

In the aerospace industry, depending on the primes’ requirements, Type 1 reference test blocks of the ISO 3452-3:1998 standard and the PSM-5® test panel are by far the most widely used.

These panels shall be used at every starting up of a PT process line and at the beginning of every shift, to check the overall performance of the line. 

Should the results on the panels do not comply with the expected patterns, after a retest, it is mandatory to: find out the causes for non-conformity; to adjust the parameters (new penetrant, check UV-A irradiance, water temperature, etc) found as inadequate; check again with the panels. If everything is then OK, all the parts inspected since the previous satisfactory check shall be processed again. If not ... there is a trouble, and a Level 3 has to be called!”

An American NADCAP auditor sent us the underneath message:

‘‘Thanks for your accurate portrayal of the scope of the NADCAP audit. It is so refreshing, and unusual, to see this in print (other than in the NADCAP newsletter).  Keep up the good work!’’

We are happy to answer him:
‘‘We thank you for your comment. We are happy to know that you spare some time to read our papers, and we thank you for your attention.
If you have any comment, suggestion, you would like us to publish, with either your name, or your "name being withdrawn upon request", please feel free to do it!
All the comments or questions we receive are valuable. Some go to the Mail Inbox with the author's OK. Others are dealt with on a confidential basis.”

Reference

• ISO 3452-3:1998 Non-destructive testing - Penetrant testing - Part 3: Reference test blocks, International Organization for Standardization, Geneva, Switzerland, 1998.