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March-May 2015 : Subcontracting a task, or how to minimize risk!

Written by Dubosc
Thursday, 19 February 2015 11:03

Halogens and sulphur titration in PT/MT is a method which requires strictness, extreme care and alertness.

Of all the existing methods, we consider that the referenced D.5713/DJX/RB 90 0295/Indice 1 procedure of EDF (ÉLECRICITÉ DE FRANCE) outstrips any other.

This 63-page document is really self-sustaining, and details written page after page let no way for double entendre.


Every element (chlorine, fluorine, bromine and sulphur) may be titrated by 3 methods and every result is given with a confidence interval.

This method dating back to 1990 has proven it is really reliable and should be considered as a standard.

First, a representative sample of the product as delivered is taken apart; a specific procedure is detailed for spray can sampling.

Titrations are carried out:

  • After combustion of combustible materials, such as penetrants and organic solvents;
  • After mineralization of products containing inorganic materials, such as non-aqueous wet developers, magnetic inks and contrast aid paints.

Combustion of combustible products is carried out in a "calorimetric bomb" with some oxygen pressure.

The principle of this widely known method is to ignite the combustible material by an electric arc between two electrodes in a pressurised atmosphere of pure oxygen.

The inside surface of the calorimetric bomb is coated with platinum(*). Both electrodes as well as the combustion bucket are made of platinum(*).

Some of you may think that this platinum ‘‘luxury’’ is a useless sophistication devised by a Machiavellian chemist marvellously cultivating the art and the way of extremely complicating everything.

Not that way! In fact, it is only for safety and analysis quality reasons.

Indeed a high content of halogens or sulphur could make the calorimetric bomb explode which could harm people in vicinity in the lab.

In the '90s, attendees of a meeting held about these titrations showed their concerns for safety.

One of them seemed so comfortable with the safety side that he looked as THE expert.

Asked about his way of doing, with the lab's manager hearing, he coolly answered:

- ‘‘Well, to lower risk combustion is carried out in the lab's corridor. Further, as interns are a common available working force, they do the job.’’

You may imagine the manager's embarrassment: he was red-faced...but did not challenge the sentences!

(*) At § 3.3.2 of the EDF document, It is mentioned "platinum" while in its appendix 2, it is mentioned on the drawing "Pt/Ir 10 %". Our opinion of chemists is that it is in fact iridio-platinum (platinum 90 % + iridium 10 %).


In the '60s, a UK Company had a motto: "for every surface treatment problem, there is a product xxxxxx" (trademark we do not display).’’

Engineers and Commercial people in this Company had made a "translation": "with every surface treatment product xxxxxx (trademark we do not display), there is a problem".

This anecdote is there only to remind everyone that problems met in workshops may be due to the suppliers/manufacturers as well as to the users.

Our idea in these documents is NOT to target anyone, but on the contrary to bring to your knowledge some interesting cases which may prevent you to duplicate the same mistakes while performing Penetrant Testing (PT) or Magnetic Particle Testing (MT).

All the ministories you will read are TRUE. We think they will be helpful:


  • First as examples of specific technical - or non-technical - requirements or peculiar problems.
  • Second to let you see that the problems do not always come where you think they should come from.
  • Third so that users feel free to ask for help from people (the experts) who may know more than they do.


If you know of examples of some interest for others, please feel free to mail them to us. They will be displayed on our website as anonymously as those already published.

One's experience may help others. In addition, any interesting problem met during audits may also help: auditors, who sometimes face incredible situations and have hard times, as well as auditees may have very useful pieces of information.

We thank you in advance for any input.

Last Updated ( Thursday, 19 February 2015 11:20 )