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Mail Inbox - Editorial November 2009

Written by Administrator
Sunday, 01 November 2009 10:16

Once again the end of Penetrant Testing is at our hands' reach

November 2009

Our last month editorial brought us an unexpected number of emails from our readers the world over. Our readers live in more than 110 countries.

As an example we have been allowed to publish in its entirety, at the end of this editorial a point of view we received.

We were far from thinking that this topic would seem valuable to so many people to write about. We cannot publish all the messages we got and the answers we have sent.
We think it more useful to present a summary.

First of all almost all of our readers followed us up and let us know they approved our writings.

Nevertheless some confirmed their aim is to substitute completely, or at least in some areas, PT with alternative methods they qualify as more reliable and "cleaner".

By experience we do not see any method more reliable than PT or MT to detect open to the surface discontinuities on very different parts in many different locations. Trying to replace these two methods, it is commendable ... even feasible in specific cases ... but what we are sure of is that PT and MT materials manufacturers as well as users (think of service companies which rarely do their tests in workshops!) won't be out of business for decades!

As per environment concerns important improvements have been made, the least one being lowering of volatile organic compounds (VOC) emissions. We are confident that constant efforts will lead to other improvements, though the "volatile, non-halogenated, non-VOC emitting solvent" will never exist; we are chemists and have some knowledge in this matter!

All the future PT lines may comprise the waste water treatment installation.

Automatic PT process lines make it easy to comply with all the parameters of every inspection step while deleting manual actions.

But a human being will still be irreplaceable when time comes to inspect parts due to the unique combination: sensor (eyes) + signal processor (brain), of course obsolete ... but which is still the only one able to see in a fraction of a second that indications are in line (and shall be considered as ONE indication), that an area currently displaying a background has today an aspect which is more like abnormal porosities; the human being is also unique in that he will have a look to an area of the part he has been instructed not to check (so as to decrease inspection time), and "bingo" he finds indications that "should never have existed" (real cases in nuclear industry: microflaws on reactor covers; in aerospace for different parts; in car industry, etc.) while a computer instructed not to check that area will NEVER take the initiative!

That's why we think hiring, training and increased motivation of inspectors are of the utmost importance.

Deleting PT, well, dream of it and build castles in the air!

Our thinking is unmoved: we are very confident PT is still there for decades!

Here is the point of view that we mentioned at the beginning of this editorial:

« - What an interesting discussion!

Doubt raising is important but announcing the death of PT is at least ... untimely. I know (and often tell) that PT is one of the pillars for our manufacturing quality. I must confess that since the last few years I put my hands in penetrant less and less, but what I see from my job close to the Quality Director in my company makes me dubious:

• More and more non-detected indications during these last two years. Occurrences thoroughly examined show that troubles come from the operators themselves, the process being really on a part and reliable: hiring, qualifying, motivating and above all keeping inspectors in the company are the number #1 problem, leading to a tremendous turn-over and quality problems hard to fix for our subcontractors and service companies. In these times of crises and lower margins finding money for high quality American- or non-American-based audits seems much easier than finding money to pay for the value brought by operators who are the keystone of the method. There is one thing I am sure of: this is one of the major challenges facing COSAC, the acronym for the French Aerospace Certification Committee of COFREND (the French Confederation for Non Destructive Testing).

• More and more troubles to design and commission new installations, even if relevant, due to an insuperable a priori targeting any new means requiring a management according to ISO 14000 or equivalent and whose commissioning is always hoped for ... elsewhere. Same reaction for surface treatments lines, metal-cleaning, stripping, chemical milling, which are generally far more dangerous for the environment than PT.

• More imagination needed to fit PT in a 100% digitalised production line, which is a specific main strength of our Company.

Adding to what was said at this meeting is that our company even if it has to look forward using TOCCATA's binoculars shall have a long-term view along a short-term pragmatism: if the aim is 100% of parts PT inspected at the end of the manufacturing process (generally as a reliable inspection just prior to surface treatment), the "targets" are the PT inspections performed during the manufacturing process, which may be "too much sensitive", expensive and time-consuming when compared to the needs. Let us go back to the basics: what are we looking for? A case-by-case risk assessment shows us that the discontinuities then looked for are in small numbers in very specific critical areas. A specific NDT method could then be designed for this specific application (for instance an ET probe scanning only once to measure the radius of curvature on the machining machine itself). This does not come as a replacement of the final PT inspection but may be the right answer from industrial risks management. This may prevent, especially for large parts, the time-consuming and full of risk cycle: short-term protection, truck loading, transport, unloading, short-term protection removal, PT, short-term protection, truck loading, etc. The overall PT performance is not really the problem, but this improvement of the industrial process leads to a better productivity.

I am not sure to have my ticket for Moscow available but I will be happy to hear about discussions and to try and know when the facts meet the fiction.”

Luc BOYER, Level 3, Corporate Quality Management of Dassault Aviation.

Our answer:

"Inspectors are really the keystone of all the manual processes involved in PT, and, as we say, PT puts many people off. Is it possible to make the entire PT process automatic? Sure a higher salary is needed to hire, qualify, motivate inspectors.

As for PT being a part of a 100% digitalised production line ... we are at a minimum sceptical. The first example was the 1978 "Integrated Blade Inspection System" (IBIS) tested in the US. In Europe the first fully automatic inspection system, known as AEOS®, commissioned in 1980, was also a failure. Nowadays no equipment is in the process of being put in service. Nor for the next decade, in our opinion.

It is true that in some cases, such as the one you explain, an automatic NDT (UT, ET) during the manufacturing process may be the right choice."

Last Updated ( Wednesday, 25 May 2011 19:53 )