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June 2009 - Yoghurt, Bread, PT

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Written by Administrator
Monday, 01 June 2009 17:17

For the attention of the PT young users

Penetrant Testing (PT) dates back to the '80s--but the 1880s!

Thus it is an old NDT method, based on the capillary effect AND on the human eyes + brain as sensor + signal processor unit.

Nowadays everything shall go fast: trains, aircraft, computers, children raising, eating culinary delicious items from ... "fast-food" entities, etc.

But think a while.

Manufacturing a yoghurt takes as long a time as it did one century ago.

Manufacturing good bread takes as long a time as it did several centuries ago.

Performing a good PT inspection requires as long a time as it did 40 or 50 years ago, even if penetrant sensitivity is by far much higher, even if viewing conditions are far better. Why?

Technical requirements of parts are also far more stringent; acceptable discontinuities are smaller and smaller, year after year; parts shapes are far more complex, and remote areas far more difficult to inspect. Parts are more expensive; any machine idling, any broken part lead to more costly consequences.

That's why parts shall be in contact with penetrant for a long time (up to 30 minutes in many cases, and sometimes far longer than that), shall be accurately washed ( that means with a low pressure for instance), shall be dried long enough to be sure that no trace of moisture stays on the part before developer application, that's why developer shall also stay on the parts for up to 30 minutes, and far longer than that sometimes, that's why inspection shall meet all the viewing conditions as stated in ISO 3059.

In short: a thorough PT inspection is in every point comparable to yoghurt or bread manufacturing: time is a MAJOR parameter. Trying to shorten the process may lead ONLY TO BAD, NON RELIABLE RESULTS.

Last Updated ( Thursday, 19 May 2011 10:11 )