Not all stainless is the same

[Appalachian spirits]

This has probably been discussed somewhere in this forum but i wanted to share this to any newbies or someone interested in fabricating a stainless pot. About 35 years ago when i started on my journey as a moonshiner i bought a nice 5x10 foot sheet of stainless at a scrap dealer to build a pot. And it wasnt cheap. I was assured it was "food grade" but not long after i started fabrication i noticed that it was RUSTING so my high chromium purchase turned out to be a dud. My experience in maching and fabrication at that point was limited to steel and aluminum so i admit i was IGNORANT to the fact that all stainless isnt the same.
The reason for this long winded post is that recently a customer wanted me to make some modifications to his awesome new stainless boiler he bought and you guessed it. It was rusting and the guy he bought it ran it for a long time. Scary but true so i am posting a link to a site that breaks down the composition of stainless as a lot of tanks and other vessels constructed of stainless arent safe.
http://www.sppusa.com/stainlesssteel_overview.php" onclick="window.open(this.href);return false;" rel="nofollow

[aircarbonarc]

Use 300 series and if a magnet sticks to it then it's no good. Also if you are welding it then tig weld and back purge, hire a professional if you arent, always clean anything you've cut or welded, stainless makes nastys when heated and exposed to air.

[Alchemist75]

I too discovered this the hard way. My boiler isn't rusting horribly but there are signs of corrosion where the heat is centered. She'll need to be replaced eventually. Lotta things that go unsaid about SS.

[OtisT]

Even “good” stainless wil rust if it’s not cared for. Little scratches, weld points, pooled water, can all lead to rust. Nothing lasts forever. Otis

[Alchemist75]

To what extent do copper boilers erode away I wonder, surely faster than steel.

[BlackStrap]

Use 300 series and if a magnet sticks to it then it's no good. Also if you are welding it then tig weld and back purge, hire a professional if you arent, always clean anything you've cut or welded, stainless makes nastys when heated and exposed to air.

The magnet trick does not always hold true, as being poor stainless material...
To tell whether or not a keg is stainless or aluminum (other than weight) ...is a magnet will be drawn to the rolled edge of the stainless keg.

The reason is when a keg is made the stainless is work hardened when forming the rolled lips on each end and will become slightly magnetized. A new USA made 1/2 barrel stainless keg is usually made from 304 series stainless.

[jimmayhugh]

Bar Keeper's Friend is great for cleaning and re-passivating 304 and 316 stainless kegs, kettles and accessories. The oxalic acid is fast working, and I've used it for years on my brewing equipment.

[LWTCS]

@jimmayhugh gets it.

Much of the problem (though not all) is that some folks are not aware that the word "stainless" does not mean that it is maintenance free.
I reference an article from a trade magazine that I read a few years ago that stated that 90% of all fuel/ethanol plants in the US use 304 stainless. 316 is not a requisite ( and will also degrade ).

Cold worked 304 SS can also magnetize because cold working exposes the carbon within in spite of the chromium "film" on surface of the material.
So the magnet test is not 100%

[Bushman]

My neighbor a retired mechanic once said to me that stainless means it stains less!

[brewmaster2014]

To what extent do copper boilers erode away I wonder, surely faster than steel.

Yes,not to mention it forms salts that are poisonous, this is why cate and maintenance is crucial with copper especially. The more I read and research copper and led free solder,the more I think I will just buy commercially made stainless steer column,which is cheaper than copper,stuff copper scrubbies in it and I'm good to go.

[Worm Food]

As stated above, "stainless steel" is exactly what it's called. Stain-LESS. Not "Stain-free".

In the food industry, for a true STAINLESS metal then pure NICKEL needs to be used. Iron, Chromium, practically no Carbon, though possibly a few other Elements can be used to alloy. I have made different food process items out of Nickel in the past, and it is unique in itself.

There are many different grades of 'stainless steel' but understand that they ALL start with a base of IRON. Iron rusts (oxidizes) as well as other Elements too. It is the mixture/make-up of the Alloy that give it the specific properties. The welding of it is another process that CAN cause weakness in its 'stain-resistance' so that too needs to be taken into account.

There are many knives on the market that are made out of many different 'grades' of stainless steel. Some rust, some are attracted to a magnet.

What most don't know/appreciate, is that 'stainless steel' is just as soft as 'mild steel'. It is because of the other Elements in the alloy that make it so much TOUGHER and that is why it is 'more difficult' to drill and work. That is what makes most people think it is 'harder', but it isn't. I only bring this up, because it matters when it comes to 'knives' and their ability to keep an edge.

Is this topic confused enough yet, or should we go on?

[MereCashmere]

Bar Keeper's Friend is great for cleaning and re-passivating 304 and 316 stainless kegs, kettles and accessories. The oxalic acid is fast working, and I've used it for years on my brewing equipment.

Can you explain your cleaning process? I’ve got a grip of BKF and would love to upkeep my stainless still with it. Does it need to be done every run? Once a year?

[Hannibbl]

Bar Keeper's Friend is great for cleaning and re-passivating 304 and 316 stainless kegs, kettles and accessories. The oxalic acid is fast working, and I've used it for years on my brewing equipment.

Can you explain your cleaning process? I’ve got a grip of BKF and would love to upkeep my stainless still with it. Does it need to be done every run? Once a year?

I’m curious about this also. I know BKF cleans stainless very well but I’m not so sure it is re-passivating the stainless.

[Skipper1953]

I’m curious about this also. I know BKF cleans stainless very well but I’m not so sure it is re-passivating the stainless.

Why are you skeptical about BKF helping to re-passivate the stainless?

[LWTCS]

Use 300 series and if a magnet sticks to it then it's no good. Also if you are welding it then tig weld and back purge, hire a professional if you arent, always clean anything you've cut or welded, stainless makes nastys when heated and exposed to air.

The magnet trick does not always hold true, as being poor stainless material...
To tell whether or not a keg is stainless or aluminum (other than weight) ...is a magnet will be drawn to the rolled edge of the stainless keg.

The reason is when a keg is made the stainless is work hardened when forming the rolled lips on each end and will become slightly magnetized. A new USA made 1/2 barrel stainless keg is usually made from 304 series stainless.

+1

[Hannibbl]

I’m curious about this also. I know BKF cleans stainless very well but I’m not so sure it is re-passivating the stainless.

Why are you skeptical about BKF helping to re-passivate the stainless?

It helps. Absolutely. But it only helps by deep cleaning the surface. You need to expose the “new” chromium in the SS to atmosphere to truly re-passivate it. Grinding the rust off and exposing the chromium to oxygen is all you really need to do.

Edit for afterthought: if is only surface rust from tools or metal dust. BKF would definitely accomplish the permanent removal of this rust.

[squigglefunk]

BKF worked on eliminating rust on my stainless steel still welds and for what its worth it hasn't returned. I made a paste and let it sit overnite. I think the acids in the BKF eat away a very thin layer to get to the chromium or something. I have also read about citric acid paste to do the same thing.

[LWTCS]

Snow Bowl and a tooth brush works great.

[greggn]

Snow Bowl and a tooth brush works great.

In the event others, like me, are asking "WTF ?" ...


Brillo® SNO BOL®
Extra Strength Toilet Bowl Cleaner
Does Your Bathroom Pass the Guest Test?™

This extra-strength toilet bowl cleaner removes even the toughest hard toughest hard water stains, mineral deposits, lime scale, and rust in your toilet. The thick blue liquid formula clings to the bowl, and its 14.5% hydrochloric acid delivers a powerful clean. Regular toilet cleaners remove bacteria, but this goes above and beyond, removing rust and hard water rings with its proprietary hydrochloric acid formula. That’s why Brillo is one of the most trusted names in household cleaning.

[LWTCS]

Snow Bowl and a tooth brush works great.

In the event others, like me, are asking "WTF ?" ...


Brillo® SNO BOL®
Extra Strength Toilet Bowl Cleaner
Does Your Bathroom Pass the Guest Test?™

This extra-strength toilet bowl cleaner removes even the toughest hard toughest hard water stains, mineral deposits, lime scale, and rust in your toilet. The thick blue liquid formula clings to the bowl, and its 14.5% hydrochloric acid delivers a powerful clean. Regular toilet cleaners remove bacteria, but this goes above and beyond, removing rust and hard water rings with its proprietary hydrochloric acid formula. That’s why Brillo is one of the most trusted names in household cleaning.

IKR!
works great non the less and plenty cheap compared to E-knox for example

[OtisT]

Thanks for the sno bol tip Larry.

[Hannibbl]

I’m curious about this also. I know BKF cleans stainless very well but I’m not so sure it is re-passivating the stainless.

Why are you skeptical about BKF helping to re-passivate the stainless?

So our conversation made me think last night. So I did a experiment with BKF. I actually do think that the BKF is a strong enough acid to eat into the stainless if you scrub it in and leave it on. I used a green emery cloth scrubber on a polished piece of stainless. I scrubbed pretty hard on one half of it and left the other half alone. I let it sit for an hour or so. The side the BKF was on left it almost a gray/blue color (as opposed to the polished stainless color) when it was wiped off. This looks to me like oxidation or the “etching” that you would want when trying to re-passivite the metal. I ground up a rust spot I have on my stills handle that is on the outside of the boiler, and put BKF on it and left it overnight. I’ll see what it looks like tonight when I get home and wipe it off.

Edit: for this experiment I used some foreshots instead of water for the BKF application. Figured it would evaporate faster and less chance of rust. Could possibly not have been the best choice as the paste dried out faster. Not sure if it needs to be wet to work. Seemed to work fine, but may have been better with water?

[jimmayhugh]

Bar Keeper's Friend is great for cleaning and re-passivating 304 and 316 stainless kegs, kettles and accessories. The oxalic acid is fast working, and I've used it for years on my brewing equipment.

Can you explain your cleaning process? I’ve got a grip of BKF and would love to upkeep my stainless still with it. Does it need to be done every run? Once a year?

I’m curious about this also. I know BKF cleans stainless very well but I’m not so sure it is re-passivating the stainless.

I either make a paste with powdered BKF or use the liquid paste in a bottle and thoroughly scrub the kettle, etc, with a green scouring pad, leave the paste in the kettle for a few minutes and then rinse thoroughly with water. After cleaning, you can also "pickle" (re-passivate) with a 5% solution of citric acid if your OCD requires it...

I use the same method to clean my Instant Pot and stainless steel frypans.

[Corerftech]

I hate to be a bubble burster but straight from my metallurgy college class:
304/316 SS, has no iron.
None.
No signs of Fe at all.

I looked at my prof and said WTH, why is it called steel. “Because it is!”.
4 series- lots of iron.
There are a ton of stainless variants and each for a purpose. Most sanitary tubing is 304 for a reason, or 316. Reactivity is lowest on that class.

Magnetic properties vary with stainless grade and class. Annealed or hardened, etc.

The world has a very short supply of nickel and without nickel, you don’t have stainless. The world is moving as much as possible to Fe based Stainless to preserve that nickel supply.

I bought my wife a Ruger pistol waaaay back in 94 right after I married her. Slab side 22 target model. Stainless. Women have very high pH btw.

She handled it, store keeper didn’t wipe it down. Came back (10 day wait so you know where I lived) to pick it up and said, “that’s not our pistol!”. Serial number matched, absolute rust bucket. I had to wait for an extra week due to work schedule so it sat for 20 days.

Called Ruger after pitching a fit with the storekeeper having refused it for a full refund and that never happens on firearms.
Ruger said- “your silly”- of course stainless rusts!

Two decades later in metallurgy- I learned proper.

I used to recycle stuff when I’m the west coast, sometimes a little stainless would find it’s way. I knew it was stainless. Scrap yard dingsong took a magnet to it- “dis metal”. Yes I know that. “No, dis metal”. Yeah buddy I know, it’s not paper or plastic thanks. “Dis metal, dis no metal”. Moving a magnet to a piece of 304, not sticking, to my SS pot, having iron in it. Wouldn’t take it as stainless.

High Titanium stainless is exceptional but is difficult to find. It’s hard as hell after work hardening. It isn’t phased by any chemistry. I dunno know it’s magnetic. I should check.

SS- It does indeed stain, less.

But to the point, not all stainless is ferrous. Much is completely non-ferrous.
Check the ASTM composition, that will elude to rust or corrosion free performance and non-reactivity.

[NormandieStill]

I'm sorry but I call BS and suggest that your metallurgy prof needed his head checking. The definition of steel is an iron alloy. Most sources don't state the iron content of steel because iron is the base metal so it's assumed. For reference, Blickmann quote the following for the composition of 304 SS

The exact element by weight percentage composition of 304 stainless steel is as follows:
Iron (Fe): 67%-71%
Chromium (Cr): 18%-20%
Nickel (Ni): 8%-12%
Manganese (Mn): ≤ 2%
Silicon (Si): ≤ 0.75%
Nitrogen (N): ≤ 0.10%
Carbon (C): ≤ 0.08%
Phosphorus (P): ≤ 0.045%
Sulfur (S): ≤ 0.03%

Also women do not have a "very high pH". They have slightly lower pH but the values are 5.8 for men and 5.54 for women (on average). That difference would not be enough for a woman handling a gun to cause stainless to rust especially as the higher acidity would be more likely to cause passivation.

Non-ferrous stainless steel is not stainless steel. It's something else entirely.