Rust Converter In place of Sandblasting

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We have a fabrication workshop, and often need to remove rust on steel plates before they can be shipped.We have recently used a Rust converter and we feel it is an environmentally better option.But there are a few Quality Inspectors who object to the use of Rust convertor and approve only the Sandblast process.We need Advice on pros and cons of both processes.And, if rust conversion is a better, what points so we keep before the Quality inspectors, to prove it.Thanks Sanjay
Reply:Originally Posted by sanjaybWe have a fabrication workshop, and often need to remove rust on steel plates before they can be shipped.We have recently used a Rust converter and we feel it is an environmentally better option.But there are a few Quality Inspectors who object to the use of Rust convertor and approve only the Sandblast process.We need Advice on pros and cons of both processes.And, if rust conversion is a better, what points so we keep before the Quality inspectors, to prove it.Thanks Sanjay
Reply:Dear Jim ,Thanks for your reply.Further i can say that the Inspectors have a defined standard for sandblasting  Like SA 2.5so  We would also like to know that What are equivalent standards for Rust Converter Viz a Viz sandblasting...like SA 2,2.5,3.Is there any approval awarded to Rust Converting By any Agencies in your Knowledge.regardsSanjay
Reply:If it is the same thing I think you mean by "Rust converter" it only changes Iron Oxide from one form to another, it doesn't remove it.  Red rust is Fe2O3, Black oxide is FeO (the common black oxide finish you see on a lot of cap screws and other steel parts).  So if you are looking to remove the oxide, the converter does not do that, and if you need to remove it, the inspectors would be correct in not approving the use of a converter.-DaveXMT304 with: 22A Feeder, or HF251 Hi Freq DC TIG air cooled
Reply:Well the rust converter I can think of is phosphoric acid and even that needs some care and attention during application. Converts rust to iron phosphate. A bad job of application is going to be a bad job no matter how you spell it. The mix %'s, the wet time and air (oxygen) exposure times all have to be ballanced out for complete conversion. Then if the rust converted is deep, loose, flakey or powdery it'll still be that way after conversion and would need some serious thought before painting. Works better as an etchant and or converting flash rust prior to painting than it does as a one shot substution to sandblasting."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Originally Posted by davecIf it is the same thing I think you mean by "Rust converter" it only changes Iron Oxide from one form to another, it doesn't remove it.  Red rust is Fe2O3, Black oxide is FeO (the common black oxide finish you see on a lot of cap screws and other steel parts).  So if you are looking to remove the oxide, the converter does not do that, and if you need to remove it, the inspectors would be correct in not approving the use of a converter.
Reply:I have used the rust converter on many projects and truck chassis..it leaves a black plastic( probably latex) coating that is not weldable, so shipping plates that need tobe welded coated with rust converter would have to be grinded or plasted off at the job sight, after welding and fabrication the converter is great stuff to coat a finished product and then can be painted, I think sand blasting and the coating the metal plates with a rust preventer would be better, finding a rust preventer that is not oil based so it doesnt contaminate the welds would be the trick. Im sure somewhere out there that product excists, I know I have had to clean oil residue of many metal parts and sheets prior to welding. I guess its easier to clean non rusted oily metal than sand blast sheets of metal before welding.
Reply:Sand blasting is hard to replace.The phosphoric acid still needs to be rinsed with waterand then will start rusting again within 4 hours.Phosphoric acid converts iron oxide to iron phosphate.What about a spray on weldable primer?Large plates sold for steel boat building are shipped withweldable primer.It saves a lot of time because then only the welded areas need to be primed for paint.Last edited by Donald Branscom; 03-07-2011 at 09:02 AM.AWS certified welding inspectorAWS certified welder
Reply:thanks everybody , appreciate your help.
Reply:While maybe not suited to your application, in my experience the rust converters shine in auto-restoration.Sometimes it is just not possible to get every darn speck of rust out of some pits.  If you paint over those, the rust will come out in about a year.  Use a rust converter over those areas before you paint and it seems to be good solution - don't see the rust coming through... ever.Rick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet