PT in France in the good ol'days of Rock and Roll

Oldies but Goodies
Written by Administrator
Friday, 01 January 2010 13:39

1- Introduction

Yes this paper deals with what PT in France was during this period. But we are sure that some of our friends the world over will be reminded similar occurrences in their respective countries ... only if (a big "if"!) they are at least 60 !!

None of us knew anything about PT during chemistry University training.

Underneath you are to find interesting pieces of information about PT and the Rock and Roll!

In the '50s PT materials were kind of similar to our Grand-Ma's recipes: formulae were published and every man in charge of PT had his own recipe (in these old times, PT world was exclusively for males!!)

As you may understand Health and Safety concerns were far from being the number 1 topic.
The first MSDS were issued in France beginning '80s.

2- The French PT ''Father''

Who was the French instigator?

He was a Top Navy Engineer, he was a honoured medal-holder: French Society of Metallurgy and Materials, 1969; COFREND, 1985, after having been its President, 1977-1979; COFREND was the Confederation for Non-Destructive Testing: Henri de LEIRIS (†).

He had designed PT materials formulae, both for colour contrast and fluorescent techniques; further he designed a test block which could be disassembled to measure materials sensitivity.

In the '50s a "RESSUAL" kit was available, comprising everything that was needed to perform a test; products were then in small bottles.

One of the first PT materials manufacturers gave Henri de LEIRIS samples of its products.
Results were astonishing and, as a humble man and a scientist, he quickly understood these products were better than his. Then he made it known that these were the ones to use.

Let us take the opportunity to talk about another Naval Engineer, René RAVAUD (1929-1986), CEO (1971-1982) of SNECMA (French acronym of: National Company for Designing and Manufacturing AeroEngines). He pushed the Company to the civil aeroengines world.

What would be SNECMA today if glued only to the military aeroengines?

René RAVAUD was the man who is famous for the motto: "You, SNECMA workers, you manufacture the engines for today use and I think of the engines for tomorrow."
Visionary, indeed he was.

In 1974 he entered a 50/50 JV with General Electric, which was then something as 10 times larger. The contract which was signed with Gerhard NEUMANN led to CFMI, now THE leader on the medium power range turboengines for aircraft: all the Boeing 737, and something as 60% of the Airbus A 320 family run on engines from the CFM56 series.

Engines manufacturers have been involved for decades in PT requirements/specs, have asked the suppliers to improve their products, and are today one of the major users of PT materials in the world.

3- Some formulae of penetrants well-known in these old times

In the first part of a long paper (*) two of the oldest penetrants formulae were written:

3.1.- Colour contrast penetrant

For one liter the formula comes as follows:
• Xylene: 498 ml.
• Tetralin: 498 ml.
• Isopropanol: 4 ml.
• Organol red: 1 gram.

This is why colour contrast PT was known as "rouge organol PT" in France then.

The "rouge organol" belongs to the SUDAN family of diazoic dyes.

Among them is the SUDAN 7B:
• Chemical name: 2-Naphthylamine, N-ethyl-1 - ((p-(phenylazo)phenyl)azo)-
• Formula: C24H21N5.
• CAS N°6368-72-5.
• Classification: Solvent Red 19, colour index C.I. 26050.
• Listed in the IARC (International Agency for Research on Cancer) Group 3, no longer allowed in the European Union for use as dyes for food since 1995. Due to some enzymes reactions they could be transformed into amines in the human body; some of these amines are carcinogenic. That's why colour contrast penetrants free of diazoic dyes have been designed.

Health and Safety data of the other ingredients are as follows:

• Xylene (or dimethylbenzene): it is in fact the mixture of the 3 isomers: 1,2-Dimethylbenzene, 1,4-Dimethylbenzene and 1,3-Dimehylbenzene.
Hazard symbol:
Xn- Harmful.
Risk phrases:
R 10 Flammable.
R 20/21 Harmful by inhalation and in contact with skin.
R 38 Irritating to skin.
Safety phrase:
S 25 Avoid contact with eyes.

• Tetralin (or 1,2,3,4-Tetrahydronaphtalen)
Hazard symbols:
Xi- Irritant, N- Dangerous for the environment.
Risk phrases:
R 19 May form explosive peroxides.
R 36/38 Irritating to eyes and skin.
R 51/53 Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
Safety phrases:
S 26 In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
S 28 After contact with skin, wash immediately with plenty of water.
S 61 Avoid release to the environment. Refer to special instructions/safety data sheet.

• Isopropanol
Hazard symbols:
F- Highly flammable, Xi- Irritant.
Risk phrases:
R 11 Highly flammable.
R 36 Irritating to eyes.
R 67 Vapours may cause drowsiness and dizziness.
Safety phrases:
S 7 Keep container tightly closed.
S 16 Keep away from sources of ignition - No smoking.
S 24/25 Avoid contact with skin and eyes
S 26 In case of contact with eyes, rinse immediately with plenty of water and seek medical advice

3.2.- Fluorescent penetrant

Formula for one liter was simple:
• Mineral oil: 750 ml.
• Hydrocarbons: 250 ml.
• Dimethylcoeroxenol acetate: 1.25 gram.

Dimethylcoeroxenol acetate is a dimethylcoeroxenol ester and, as for all the coeroxenol esters, it has a strong colour. Dimethylcoeroxenol acetate emits a yellow fluorescence. We do not have any other information about this dye from the anthracene family. Maybe it is known under another chemical name as no CAS (Chemical Abstract Service) number is available; maybe it has never been registered.

Re: the other ingredients. We lack important information about them and cannot tell about the associated hazards.

Mineral oil may contain very hazardous impurities if not refined--and it was not in these days!

Hydrocarbons are listed as "Harmful" nowadays when they were considered as safe then!

4- When a renowned aeroengine manufacturer manufactured it's own PT materials

In the '50s a renowned French aeroengines manufacturer designed PT materials for use in its plants.

4.1.- Colour contrast penetrant

Then called "red liquid" it was as follows:
• Butyl lactate: 120 mL.
• Ethanol 95%: 120 mL.
• Toluene: 10 mL.
• Rhodamine B BASE: 10 grams.

Though emitting an orange fluorescence under a UV-A radiation this penetrant was used only as a colour contrast one.

In our DPCNewsletter number 17 - Oct 2009 issue on our Website:
which deals with "Special Products for PT", in the chapter "Dual-Purpose Penetrant" you may find what shall be known about Health and Safety of rhodamine-based penetrants.

As for the other ingredients:
• Butyl lactate: This ester is no longer used in PT materials.
Hazard symbol:
Xi- Irritant.
Risk phrase:
R 36/37/38 Irritating to eyes, respiratory system and skin.
Safety phrases:
S 26 In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
S 37/39 Wear suitable gloves and eye/face protection.

• 95% ethanol: This is the azeotrope ethanol/water; very likely ethanol is "denaturated" as per applicable regulations. The denaturant quite often is methanol, sometimes diethylphtalate, or thiophene or even diethylether. This alcohol is no longer used in penetrants.
Hazard symbol:
F- Highly flammable.
Risk phrase:
R 11 Highly flammable.
Safety phrases:
S 7 Keep container tightly closed.
S 16 Keep away from sources of ignition - No smoking.

• Toluene: This is a benzene-family hydrocarbon no longer used in penetrants. It would be forbidden nowadays.
Hazard symbols:
F- Highly flammable, Xn- Harmful.
Risk phrases:
R 11 Highly flammable.
R 38 Irritating to skin.
R 48/20 Harmful: danger of serious damage to health by prolonged exposure through inhalation.
R 63 Possible risk of harm to the unborn child.
R 65 Harmful: may cause lung damage if swallowed.
Safety phrases:
S 36/37 Wear suitable protective clothing and gloves.
S 62 If swallowed, do not induce vomiting: seek medical advice immediately and show this container or label.

• Rhodamine B: see above.

4.2.- Developer

The so-called "white liquid", the non-aqueous wet developer, was as follows:
• Light precipitated calcium carbonate: 45%.
• Ethanol 95% pure: 55%.

Ethanol, though sometimes still used in non-aqueous wet developers (NAWD), very often has been replaced by the isopropyl alcohol since decades. Without denaturant its smell is more agreeable than denaturated ethanol's. Further isopropyl alcohol contains only 0.5% maximum of water. This is very important as, when in contact with water, calcium carbonate gives lumps, unacceptable for a developer. Calcium carbonate content is high in our opinion. In NAWD capillary agents content is close to 25%. This developer is too high in solids and was difficult to spray as an even, light coating. Likely to lead to too a thick layer.

As per Health and Safety concerns:
• Calcium carbonate: this is chalk, calcite, also called "Meudon white" or "Spanish white". Calcium carbonate by itself is not hazardous, except if it contains asbestos (which leads to asbestosis) or crystallised silica (cristobalite and quartz) which may lead to silicosis.

Nowadays calcium carbonate used in developers is directly synthesised and no longer extracted from mines, which is a guarantee that there is no asbestos and no crystallised silica.

• Ethanol 95% pure: see above.

Here now is the PT process from these days, with some comments:

• Degrease with trichloroethylene
Comment: titanium alloys were not used in aerospace industry yet.

• Apply the "red liquid" with a brush.
Comment: though spray cans were used for some applications from the very first years of the '50s decade (**), no one then imagined that PT materials could be used this way.
No penetration time specified.

• Wipe off with a dry rag.

• "Washing" (Comment: "wiping" would be better) with a rag saturated with alcohol (Comment: ethanol 95% pure) until there is no trace of the red liquid. Allow 5 minutes for drying.

• Using a gun spray the white liquid (the developer) after thoroughly shaking it.

• Allow 5 minutes for drying; if there are cracks they appear as red against the white layer.
Comment: this developing time is a bit too small.

• If, due to some wrong doing, some cracks which showed up are wiped out, wipe the part with a dry rag and spray again only the white liquid. Cracks will appear again against the white layer. This step may be renewed two or three times.
Comment: if so doing it is likely that indications will not appear again, which is detrimental to the process reliability.
Nowadays in such an occurrence the part would be completely and thoroughly cleaned to come back to the same cleanliness as at the process' beginning. The PT process would be completely run again. In fact as described this step is only a "doubt-removal" which can be done only when using fluorescent penetrants as explained on our Website (***).

5- Conclusion

We thought it useful to come many years backwards. As the motto says we are dwarfs perched on giants' shoulders: let us honour the PT pioneers.

With this paper our idea is only to bring into focus all the improvements of PT since these Good Ol' Days when Rock and Roll surged.


(*) Claude HUGUES and Pierre CHEMIN, Contrôle Non Destructif par Méthode de Ressuage, Revue bimestrielle Pratique du Contrôle Industriel-Qualité, N°78 à 83 (avril 1976 à mars 1977). Editor's note: Non Destructive Testing by PT method.

(**) Pierre CHEMIN and Patrick DUBOSC, Penetrant Testing History: On our Website.

(***) Pierre CHEMIN and Patrick DUBOSC, The Wipe-off technique: On our Website.

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 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.

Last Updated ( Sunday, 10 June 2012 14:11 )