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June/July/August 2015 : A tried and true developer ?

Written by Dubosc
Friday, 15 May 2015 08:47

Users are never short of ideas!

We got a phone call from a Services Company:

- "One of our customers wants to use a colour contrast penetrant with a wet developer. They have mixed dry developer with water at room temperature. They use a "garden-spray" (used to spray chemicals on flowers, plants, etc.) to spray this product on the part after excess of penetrant removal. They do not understand why there are red drips, why the developer layer is quite thick, why water does not evaporate. Why they do not succeed?"

- "But why do not they use the standard non-aqueous wet developer (solvent-based developer)?"

- "They say it is too expensive, and that they are able to design their own developer, very cheap!"

- "And you, Sir, what is your opinion?"

- "I'm a Level 2 PT certified inspector, I told them not to do that, but I do not have the technical knowledge of your products which could convince them they are wrong!"

- "Well, Sir: the developer used with colour contrast penetrants shall be applied in a thin layer, evenly on the entire surface, must wet the surface but MUST evaporate within 30 seconds to 2 minutes. If the developer stays wet for a long time on the surface (very cold surfaces for instance) the penetrant which comes out of the discontinuities will spread in the developer coating, giving rise to dimmed indications with a poor contrast. The developer may give the drips as seen with this...mess!"

The developer they have "designed" is based on two flaws--at least!

- First, they used a dry developer to be mixed with water. Dry developers are designed not to mix with water!

- Second, using water instead of an alcohol leads which needs a far too long time to evaporate!

Conclusion: the product they have prepared may be cheap...but they lose a lot of money by using it... as they have to clean again all the parts, let them dry, then apply again the penetrant and process the parts the way they have to!"

Penetrant Testing may seem a very simple method: a bit of cleaner, a bit of penetrant, wait for a short time, then, spray the cleaner again on the surface while wiping with rags, then generously apply the developer, then wait for a short time and inspect. Seems you never saw such a way of doing???

Training future users for several days is necessary: and even if we have in front of us future Level 3s for an entire week, they will not know 1/100th of the knowledge and expertise that penetrant materials manufacturers have accumulated along the years.

We have been more often than you may imagine in front of "peculiar ideas" from users, but also from Production Managers, from Purchase Department people, from young financial people: for instance, when you look at a penetrant line, you may see parts which DO NOT MOVE for half an hour! (contact time with the penetrant, or with the developer, as examples!). How costly it is to have so many square meters allowed to non-moving parts!

We will probably give you some interesting mini-stories, just to make you think about what we have to face, we, the penetrants knowledgeable people!!!

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 Patrticle 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 ( Friday, 15 May 2015 10:07 )