Chemical Forums
Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: rstor on December 30, 2014, 05:09:16 PM
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I would like to store/dispense Isopropyl Alcohol (99.9% Anhydrous or 99%). The dispensing container that I will be using is made of galvanized steel (Justrite 10018 [Galvanized] Steel Plunger Can). The IPA is for electronics use (removing flux, cleaning PCBs).
According to Justrite (who manufacturers the storage can), they mentioned in the link below that 70% IPA is not recommended to be stored in a galvanized steel can (they recommend stainless steel or polyethylene).
http://www.justritemfg.com/Documents/Know-it-All%20docs/Compatability%20Chart%20-%20English%208-2013.pdf (http://www.justritemfg.com/Documents/Know-it-All%20docs/Compatability%20Chart%20-%20English%208-2013.pdf)
I am assuming this is because 70% IPA contains 30% water which has the potential to rust galvanized steel over time, is this correct?
According to The Dow Chemical Company they mentioned in a document that:
"..Transfer lines may be of carbon steel. For Isopropanol, 91 or 95 percent, stainless steel, galvanized or lined piping should be considered if rusting is to be eliminated."
Would storing 99.9% or 99% IPA in a container made of galvanized steel cause rust or any other issue which would compromise the safety of the container?
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There is likely a trace or more of water in the IPA, more over time as it absorbs moisture from the air. It is also possible there is a trace of acid -- exactly what reaction will cause that I don't know. But unless its a buffered solution, or a pure aprotic solvent, its always possible for the pH to lower. And that will attack the zinc coating. This seems to be conventional wisdom, a galvanized container is never for storage of anything, just for temporary use, then rinsed out and stored dry. Maybe, if you search around a bit, you can find the source for the wisdom -- but generally, galvanized steel really isn't a magical, never rust forever, container.
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In the link posted in the opening post the manufacturer mentions IPA 70% is not recommended to be stored in galvanized steel however the manufacturer indicates that Ethanol is considered good. Searching online I found that Ethanol also absorbs water from the atmosphere.
Arkcon mentioned that there is also a possibility of a trace of acid in the IPA. Does this possibility also hold true for Ethanol?
Chemically is there a major difference between Anhydrous IPA and Anhydrous Ethanol with regards to these chemicals reacting with galvanized steel?
Do you think that since the manufacture indicates Ethanol is ok to store, that the reason why IPA 70% is not recommended is because of the high water content and if Anhydrous IPA is stored it would be similar to storing Anhydrous Ethanol (which is marked as good to be stored in galvanized steel)?
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Well now, that's just confusing. Ethanol is likely way worse than isopropanol in regards to trace acid contamination. Microbes can even convert ethanol into acetic acid, if there's enough moisture around to let them gain a foothold. I suppose it all boils down to how long alcohols are stored, and how much water they can absorb. An expert may be able to provide more specific help.
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After searching online I found a book authored by an expert, Frank C. Porter, who is considered "one of the foremost authorities on zinc"
http://www.galvanizeit.org/knowledgebase/article/hot-dip-galvanized-steel-in-chemical-solutions (http://www.galvanizeit.org/knowledgebase/article/hot-dip-galvanized-steel-in-chemical-solutions)
In the book entitled "Corrosion Resistance of Zinc and Zinc Alloys"
http://books.google.ca/books?id=C-pAiedmqp8C&q=isopropyl+alcohol#v=onepage&q&f=false (http://books.google.ca/books?id=C-pAiedmqp8C&q=isopropyl+alcohol#v=onepage&q&f=false)
on page 418, Table 5.6: "Corrosion of Galvanized Steel in Contact with Organic Chemicals -- Specimens of galvanized steel partially immersed in commercially pure test chemicals at ambient temperature of a minimum of 100 days; corrosion rate based on total area of specimen." The author indicates that for the corrosion media of Isopropanol (anhyd) and also (19 vol %) the corrosion rate (mils/year) is <0.5. The rate for 190 proof Ethanol is 1 (which agrees with what Arkcon mentioned about Ethanol being worse)
From the above am I correct to understand that for Anhydrous IPA the corrosion rate is <12.7 micrometers (<0.5mil) per year. How significant is this corrosion rate? Does this mean that after 50 years <0.635 millimeters of the galvanized steel would be corroded? Also when the author mentions "19 vol%" does this mean 19% IPA?
I've also found two chemical resistance charts. One from Hoffman:
http://www.alliedelec.com/images/products/mkt/pb/hoffman/pdfs/ChemicalResistance.pdf (http://www.alliedelec.com/images/products/mkt/pb/hoffman/pdfs/ChemicalResistance.pdf)
Where they mention that for Steel, Galvanized, G-90, IPA has a rating of 1-1-1
"The order of these numbers represents 30, 60, and 120 days of total submersion of the substrate in each chemical at 72° F (22° C).
1 Recommended — Unaffected by chemical; no deterioration
2 Satisfactory — Very little effect; reduced aesthetics probable over time
3 Limited use — Chemical attack probable with slow deterioration
4 Not recommended — Severe attack is imminent; rapid deterioration."
In the second chart by Steven Engineering:
https://stevenengineering.com/tech_support/PDFs/71ISPCHEM.pdf (https://stevenengineering.com/tech_support/PDFs/71ISPCHEM.pdf)
It lists Isopropyl Alcohol with a rating of S for Steel (Galvanized)
S = superior resistance /
completely unaffected
under all conditions
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From the above would it be safe to assume that the previously mentioned galvanized steel storage/dispensing container would be fine for storing/dispensing 99% IPA or 99.9% Anhydrous IPA?
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The welding flux uses to be slightly acid and will end in the solvent.
99% is the purity of the new alcohol, right? After use, it will contain fat and salts from fingers, and so on.
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Plan on using either 99% or 99.9% IPA. I'll use a clean cotton swab, kimwipe, or drop dispenser each time when dispensing to minimize contamination from any alcohol that is not absorbed and is drained back into the main reservoir.
Similar to how they are using it here:
https://www.youtube.com/watch?v=zHXLIV9DlsY (https://www.youtube.com/watch?v=zHXLIV9DlsY)
Hopefully these measures will be adequate to prevent contamination?
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To solder with an iron, the wire contains a flux, often composed of colophane and additives, that deoxidizes copper - nothing innocent! In some uses, residues of this flux are removed to avoid further corrosion (satellites use a wire without flux, which hence doesn't solder anything, and later complain about bad solder points).
This flux ends in your solvent, here Ipa, which won't be pure any more. This is its role as a solvent.
Industrial welding is made by leaching a solder cascade of liquid metal, but I expect then printed circuit to be covered with some flux in advance. It carries also vanishes which will probably dissolve a bit.
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I've returned the steel galvanized dispensing container. I am now trying to decide between either this:
(HDPE bottle with Stainless Steel pump)
http://menda.descoindustries.com/MendaCatalog/PumpAndBottle/StainlessSteel/Natural/35396/#.VKm_JSvF_ps (http://menda.descoindustries.com/MendaCatalog/PumpAndBottle/StainlessSteel/Natural/35396/#.VKm_JSvF_ps)
or this:
(HDPE container with plunger assembly made of Brass and Ryton)
http://justritemfg.com/products/safety-cans-and-containers/plunger-and-dispensing-cans/plunger-cans/plunger-dispensing-can-1quart-hdpe/ (http://justritemfg.com/products/safety-cans-and-containers/plunger-and-dispensing-cans/plunger-cans/plunger-dispensing-can-1quart-hdpe/)
The one made by Justrite indicates that the "perforated upper pan serves as a flame arrester". I am not sure if the brass used will be an issue with IPA.
My main concern is fire safety. I like the feature of the dispensing pump by Menda as it prevents the main reservoir from getting contaminated.