Removing Rust from Stainless Steel

How about a wire brush?

How about a STAINLESS STEEL wire brush.

A mild steel wire brush will cause rust wherever it is used on SS.

But then, I'll bet you knew that.

LL

Hi DH - what is the guage thickness of the panels? it might be better to replace...as to be rid of the corrosion, you will need to resurface/grind the panels to remove material...if you want to eradicate the issue - then you have to continue with protective oils/solvents to keep it from reappearing (there is foodsafe cert's available)

Do you know what spec. the SS is? what has caused the corrosion - caustic cleaners? Abrasions? just eliminating the surface rust probably won't solve the problem (making it look better) if the same process continues during your production cycles

GA Guest. If this is truly surface rust, just about any other action does more harm than good to the surface.

in my experience:

Aerokroil is the best for sprying on prior to application of the Scotch Brite pads attached to my hand held battery operated tool.

I have a couple of steel bench blocks that have developed spot rust here and there. What I use is wet/dry sandpaper and flush it away with water - working up from 400 to a 2000 grit to get a smooth and highly polished surface. The smoother the surface, the less prone for rust to redevelop. To get rid of any residual moisture, there are products which are certified for use in a food professing facility, for example check out Walter Surface Technologies. Some of their stainless cleaners might be a better choice for an overall 'sheen' of rust condition (as opposed to spot rust which has to be sanded/ground off).

Dependent upon the severity and quantity of rust present, you can remove with phosphoric acid but it will be somewhat slow . However, if you want to leave a protective film afterward, then you will automatically leave an iron phosphate rust inhibitor (film) after removing the rust.

Another faster way using acids would be to use hydrochloric followed by phosphoric... Then, again, remember that fuming hydrochloric can be very hazardous especially if concentrated where it emits vapors. The common name for industrial hydrochloric is MURATIC and used in the removal of residual mortor after brick work. It can be found in almost any retail outlet. As to phosphoric,- It is purchased in bulk at municipal wastre treatment plants as a fertilizer for bugs and should be easily obtained there if you ask nicely.

If you are in the States you an buy a cleaner for stainless steel called "Bar keepers friend". BKF . It is in powder or liquid and it works wonderfully

Elbow grease and abrasive methods using abrasives is the best answer - start course and end with a polishing grade. I doubt if the rust is so heavy as to need chemical cleaning.

You should use the BKF product. it is non toxic and as you said the traces of rust are from a carbon steel brush. the BKF is also slightly abresive and cleans wonderfully

I have refinished rusty old SS kitchen sinks using a steel wire brush in an electric drill. It is quick and easy and it leaves a "brushed" finish that makes the sink looks like it is brand new.

Interesting.

i would first find out what is causing the rust. i bet it is your sanitizer you are using. most sanitizer have bleach derivative in them. chlorine, chloride or any form with cause SS to rust or corrode. so watch your concentrations. as for cleaning Bar Keepers works well or might have to sand it down. which can cause it to rust easier. we would sanitize after use the put mineral oil on the surface to make it shine. then sanitize before use. most SS polishes have a mineral oil in it that is what SS shine.

Chlorine based sanitizers should be kept away from SS.

Most SS is prone to intergranular corrosion where chlorine corrodes along the grain boundaries.

Chlorine also encourages stress corrosion where it corrodes preferentially in areas of highest stress.

http://www.mcmaster.com/#pickling-gel/=2rvp52 and look towards the bottom of the page for pickling and passivation paste/gels for s/s. I have used both of these products and they work pretty well. If your rust is really bad you may need to use several coats but it will leave a nice appearance afterwards. Be very careful when working with this stuff though and be sure wear the appropriate PPE because of the ingredients is type of acid in them that can burn the skin somewhat. I have found that many different acids will remove rust from s/s but they can be very dangerous to the s/s material and person and these solutions are designed passivate the surface as well.

Careful - This is a paste form of the nitric/hydrofluoric mixture I mentioned in post #12. We (the company I work for) use it to remove weld marks on unpolished skid frames. If this is in a USDA facility as mentioned in the original question, the stainless most probably has a polished finish of at least 32 Ra. This paste, as with the acid mixture, will make very short work of removing the polish and leave a nice flat patina, similar to a bead blasted surface. Then you are looking at repeating the problem by finishing the surface again, which is where we are all assuming the iron (rust source) contamination came from.

I agree 100%, I was answering the question as he asked it and not assuming it was polished s/s because he did not mention it in his description. if I start guessing what a poster is really trying to say I nearly always get it wrong. If it is a polished surface and also has surface rust then I would think that the polishing may have already been compromised to the point of having to start over with the finish. I usually do not work with polished s/s but more a mill finish s/s pipe (304L, 316L, inconel and duplex s/s) We passivate all our welds to remove weld color and to give it all a more finished look with the paste form of this product.

We do the same thing with the little utility piping we do, and frames for process skids, when they are for use in utility rooms, not in production areas. On very large sections, we have the 1500 gallon tank of the liquid version of this paste. However, we do mostly what he probably has in his plant - sanitary finish. The mention of the USDA almost insures this is at least a 32 Ra finished product. The previous mention of the on-site electro polishing was to insure the restoration of the finish. These companies usually also have a mechanical polishing group that would not use any carbon steel products on his part, and would finish up with a nitric passivation to insure no rust return. However, the concern about carbon steel products rubbing against the part in his plant still remains. All the above will do no good if a pracice in his plant is allowing contact with carbon steel.

I have to warn you- if you are not already aware- of the danger of using any product with hydrofluoric acid. HF is absorbed through the skin. It may not appear to have any ill effect- no local burning on the skin, for example, but it migrates to the bones where it can do serious damage.

I doubled as the Safety Director here for 10 years - see my post #12 where I tell all to get an MSDS on hydrofluoric before using.

Derald,

Mate. You still haven't said what grade of stainless it is you've got the problem with. Does a magnet stick to it? Do you want an easy, cheap fix or do you want to attack it with seriously corrosive acids, or, mechanical grinding, polishing etc?

The very worst thing anyone can do is to 'assume' when giving advice.

It seems that all the replies have had to assume a lot.

I assumed that because the alloy is where it is, and what's happening to it, that you've got 304gr stainless steel. This is being attacked by the acids in the foodstuffs (meat) passing across it on a daily basis. The ferrous particles in the alloy are oxidising, manifesting in rust 'staining' rather than full-on flaking rust. Is this so?

If it is, there is a plethora of methods getting rid of the stains, from a quick scrub with a dilute food acid (Coke) which is happily reasonably biodegradable, to various proprietary abrasive powders, some of which require a great deal of elbow grease.

Which is it?

For my own part, I'd like to think that I've been of some help to a post, and I'd like some feedback.

No offence intended.

Cheers,

Stu.

Where is the OP on this thread? Lot's offered - little gained