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Alternatives to trichloroethylene to vapor degrease parts



An ongoing discussion from 2001 through 2014 . . .

(2001)

Q. I now vapor degrease aerospace parts with trichloroethylene. Are there good alternatives?

Thanks,

Chris Laudani
- East Longmeadow, Massachusetts


(2001)

A. Well, there are some new and very expensive proprietary "non-CFC" vapor degreasing solvents as alternatives to tri-chlor and TCA. But the basic thrust of the movement has been to try to switch to aqueous cleaning when possible -- almost always possible for steel parts, more difficult for aluminum, and quite troublesome for mixed metal.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2001)

A. A think a lot depends on your application. For some you might try one of the aqueous or citrus degreasers but for some applications I have never found anything as a specified alternative. I hope someone can correct me because I would love to find an alternative too. I know some of the studies failed because of residues on the items.

Ciaron Murphy
- Great Britain


(2001)

A. Nothing will ever be as effective as good 'ol tri-chlor! There are fluorinated solvents that work extremely well. Only problem is that they are quite expensive and evaporate at an even faster rate than tri-chlor. So a lot of your $$ disappears, so to speak. If your application is somewhat of a closed environment, though, they may be worthwhile.

Karl Hermann
- Ft. Wayne, Indiana


(2001)

A. Alternatives to trichloroethylene (TCE) are becoming essential, especially in Europe where the compound is now classed as a Category 2 carcinogen with an R45 risk assignment.

There are two possible options open:
1) switch to an alternative solvent for vapour degreasing such as
a) perchlorethylene (PCE), which has a lower health risk (R40) and fewer penalties for use, or
b) stabilised n-propyl bromide, which carries only an R20 health risk.
2) switch to aqueous cleaning.

The first option has a number of benefits over aqueous cleaning and in stand alone situations where the cleaning is not followed by further aqueous processes, it can be demonstrated to be more environmentally sound. N-propyl bromide is widely gaining acceptance as a drop-in alternative to TCE, including a number of aerospace companies such as BAE Systems, Airbus, Lockheed-Martin. Boeing is however still testing for approval. It can give cost benefits over TCE and is also safe to use on oxygen system parts and in electronic applications. The latest information I have indicates that it is about to get a SNAP approval for metal cleaning applications.

Regard,

Geoffrey A Wright
- UK



July 14, 2009appended

Q. We do Surface Treatment Process of Copper components. In this process, the 1st Step is Vapour degreasing, using Trichlorethylene as solvent at 85 °C, to remove oil & grease from the surface. Now, we're finding the best substitute for the Trichlorethylene, that will serve the same purpose fruitfully.

So, provide me the name of the chemicals (also mentioning the Operating temp. & other controllable parameters), which will be the best substitute of Trichlorethylene?

SOMNATH DEY
Exec- Chemical Process Control - KOLKATA, WEST BENGAL, INDIA


August 5, 2009

Q. Hello, we manufacture parts in titanium and also nickel / chrome based alloys. We would like to use vegetable based oils for the machining operations instead of mineral oil, but the mixture of this vegetable oil with hydraulic oil leaks from the NC machine is difficult to clean with our existing aqueous cleaning machines.

What product (for aqueous cleaning) or other process would you recommend? The ideal solution for us would provide good cleaning results for both the cleaning of mineral and vegetable oil on machined parts. Would vapour degreasing with nPB solvents (e.g., EnSolv) work for that? What about new dry processes like SCO2 or cryogenic blasting? These look promising but not for large parts (>1 m diameter) and on heavy soils.

Thanks a lot for your help.

Jean-Raphael

Jean-Raphael Ouin
aerospace manufacturing - Paris, Ile de France, FRANCE


November 19, 2009

A. Have you considered plasma cleaning? Plasmas are a dry, environmentally friendly alternative to solvent cleaning/degreasing, use no harmful chemicals and produce ultra-clean surfaces with complete removal of organic residue.

Terry Whitmore
- Warrington, Cheshire, UK


January 7, 2010

A. We use tons of TCE as of now for degreasing the metal stamped parts and deep drawn parts used in motor making.
Aqueous is bit risky if not done properly. As such we tried several alternatives and for one application we could use MTO instead of TCE..
TCE is a wonderful degreasing agent and nothing is as powerful as this.
We are in the process of trying Acetone and yet to see the success.

Uppili
India

S UPPILI
- chennai, India


January 2010

!! Readers please note that Acetone is flammable though! Maybe not a big issue when applied with a cotton Q-tip, but a significant concern when "tons" are used in a big open tank in a production environment.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


Need REACH-compliant replacement for trichlorethylene

June 5, 2014

Q. I am in the Aerospace (Aircraft manufacturing) industry and am looking for a suitable replacement for Trichloroethylene, it must be REACH compliant. We are processing aluminium, steel and titanium materials.

Portia Ditsele
Aerospace - South Africa


June 10, 2014

A. Hi Portia,

It is so difficult to have a truly "REACH compliant" solution to TCE as the goalposts keep moving. In the short term you could consider perchloroethylene or methylene chloride, these have similar solvency to TCE, but different boiling points. These both have a R-40 risk phrase, so eventually will end up on the SVHC list.

n-Propyl bromide is probably not going to be around as a cleaner much longer as it has an R-61 classification in the EU nowadays and will end up on the SVHC list sooner rather than later.

You could consider the HFEs as marketed by 3M or the HFCs as marketed by DuPont. These are considerably more expensive than TCE, but are unlikely to be caught by REACH too soon (although watch out for the F-Gas regulations).

Of course you could move away from solvent cleaning altogether and look at aqueous cleaning. Aqueous technology has moved on a huge amount in the last few years and combined with the correct equipment can be just as effective as solvent cleaning. You are better off talking to local reps about this possibility as there are a lot of companies manufacturing aqueous cleaning chemicals.

You could look at some of the more exotic technologies such as plasma cleaning or dry ice blasting. These are likely to have a cost implication, but may well be worth looking at, even if you don't go down that route.

Finally you could move away from cleaning technologies that may need the use of expensive chemicals and/or equipment. If the geometries are simple then simple swab degreasing with one of the many solvents marketed for this process may well work for you. Look at the iso-parafinnic hydrocarbons, these have become quite popular over the last few years for swab degreasing. You could always go with some of the more common solvents such as acetone, MEK, iso-propyl alcohol etc, but be warned these are highly flammable so need special precautions for use.

Brian Terry
Aerospace - Yeovil, Somerset, UK


July 16, 2014

Hello Portia,

I am confronted with this type of question on a daily base, having lots of well-known customers in aerospace.
Wherever an ECSA Type IV or V machine is involved, normally it should be no problem to re-adjust the machine from usage of Trike and Change to Perc.
Perc is the best solvent next to Trike and in 95% of all applications usable.
Type V hermetic sealed degreasing machines operating under vacuum also come very close to the temperature range of Trike.
So-called "alternative" solvents like the HFE,HFC and npB are practically not usable in state-of-the-art machines according ECSA IV and V, only in the old style open-top machines with the related emissions and running costs for continuous consumption and refill.
In Europe they are absolutely minor in number of applications.
Trend in Aerospace is usage of Perc and modified alcohols.
-> for sustainable usage but only in most modern equipment, emission free.

See the recent discussion going about cost pressure in aerospace-manufacturing coming from the carriers down to the manufacturers and their suppliers:
A replacement of Trike by just seeking a solution in a complex and expensive aqueous machine in operation and quality control, just to be virtual more "green", does not help.

BTW: we offer aqueous as well, where it is suitable on application.
Certainly not on composites and also not where NDT is involved -> solvent is the answer.

Michael Hoeckh
- Neuenburg, Germany

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