December 2011 - Methods and techniques in NDT: a quite usual confusion, again

Revised in February 2012

Once again, we have to draw our readers’ attention to some terms used on Websites and in documents, meetings, conferences, training documents, etc.

This month, the topic is "methods" versus "techniques", terms that, although they mean different things, are often used one for the other in Non Destructive Testing (NDT).

Many people around the world, even technical ones, speak about, for example, magnetic particle testing (MT) as a "technique", when, in fact, it is a "method".

Let us set the record straight, finally:

The following definitions are given in the EN 473 – 2008 standard and they will be replicated in the future normalized ISO 9712 standard.

• "Non-destructive testing method: Discipline applying a physical principle in non-destructive testing."

Example:
- Visual testing (VT), penetrant testing (PT), magnetic particle testing (MT), ultrasonic testing (UT), Eddy current testing (ET), industrial radiographic testing (RT), leak testing called "leak tightness testing" in EN 1330-8:1998 standard (LT), acoustic emission testing (AT), etc. are "methods".

• "Non-destructive testing technique: Specific way of utilizing an NDT method."

Example:
- In Penetrant Testing(1), penetrant application by electrostatic spraying (ESS), developer in dust storm cabinet, excess penetrant surface removal by water washing, wipe-off, dip rinse, etc. are "techniques".

- In the same way, in magnetic particle testing(2), magnetization by: magnetic flow, current flow, swinging field, threaded bar/conductor, induced current flow, etc. are also "techniques".

As you see, the situation, regarding the use of terminology is very similar to the one we wrote about very recently regarding:
- The "black light" term (3).
- White light vs visible light(4).

Even if the wrong terms are widely used, even if they appear in many documents, it is time to think about it … and to adjust the training documents, to adjust Websites, standards, specifications, procedures every time they are modified. Within very few years, the terminology used in these documents will comply with the standardized terminology.

References

(1) Pierre CHEMIN and Patrick DUBOSC, PT Lexicon, April 2010 (completed and updated in October 2011): on our Website.

(2) Pierre CHEMIN and Patrick DUBOSC, MT Lexicon, March 2010 (completed and updated in September 2011): on our Website.

(3) Patrick DUBOSC and Pierre CHEMIN, "Black light", Editorial July/August 2011: on our Website.

(4) Patrick DUBOSC and Pierre CHEMIN, White light vs visible light, Editorial October 2011: on our Website.

Normative references

• EN 1330-8:1998 Non-destructive testing - Terminology - Part 8: Terms used in leak tightness testing, European Committee for Standardization, Brussels, Belgium, 1998.

• EN 473:2008, Non-destructive testing - Qualification and certification of NDT personnel - General principles, European Committee for Standardization, Brussels, Belgium, 2008.

• ISO 9712, Non-destructive testing - Qualification and certification of personnel, International Organization for Standardization, Geneva, Switzerland.