My conical not all sanitary stainless??

[Roxhambrewshed]

I have a mystery concerning my 7 gallon Blichmann Fermenator.
This is what I have always been told on how to check the quality of stainless steel: "So the “magnet test” is to take a magnet to your stainless steel cookware, and if it sticks, it’s “safe”—indicating no nickel present—but if it doesn’t stick, then it’s not safe, and contains nickel (which is an austenite steel). "
So the mystery is that when I did the "magnet test" it Almost passed. The cone, lid, legs and all the hardware passed but NOT the sidewalls!!
I guess my question are if it perfectly safe/sanitary and how this can be?

 

[AlexKay]

Austenitic stainless can be mildly magnetic, depending on how it’s worked and handled. How hard did your magnet stick?

 

[mac_1103]

I must be missing something. Why does a fermenter need to be magnetic to be safe or sanitary?

 

[AlexKay]

I must be missing something. Why does a fermenter need to be magnetic to be safe or sanitary?

“Stainless steel” covers a really broad range of alloys with a correspondingly broad range of compositions and properties. Some are less corrosion resistant. Some are ferromagnetic.

It just so happens that 304 and 316 grades (and ideally you’d have 304L or 316L) both have superior corrosion resistance and are non-magnetic.

So if a magnet sticks to your stainless, it’s (probably, unless you have something unusual on your hands) a grade that corrodes more easily. Or it’s not stainless steel at all.

Except sometimes you have perfectly good 300-series stainless and a magnet sticks to it weakly, which is what I was asking the OP.

 

[hotbeer]

I wouldn't make any assumptions about the stainless steel based on a magnet test. Especially if you don't know what type of magnet that is.

Neodymium magnets stick to stainless steel when most others won't. And they stick as well to stainless as the others do to regular steel.

And there are several other types of permanent magnets some with varying power of magnetism.

 

[z-bob]

Austenitic stainless steel contains nickel and martensitic usually does not, but austenitic is also more corrosion resistant. Why do you think either is unsafe? Alloys used for orthopedic implants do contain nickel.

 

[AlexKay]

I missed that the OP got things backwards! @z-bob is right; you want nickel in your stainless; or, more specifically, you want 304 or 316(L), which both have nickel and are more corrosion-resistant than other grades.

 

[Roxhambrewshed]

Austenitic stainless can be mildly magnetic, depending on how it’s worked and handled. How hard did your magnet stick?

I used a rare earth magnet, which held itself on the side of the conical.

 

[PCABrewing]

I'm still not seing the connection that the OP makes to "Sanitary".
I don't believe leaching Nickel would be "considered" unsanitary, is that what the OP is getting at?

 

[Roxhambrewshed]

Austenitic stainless steel contains nickel and martensitic usually does not, but austenitic is also more corrosion resistant. Why do you think either is unsafe? Alloys used for orthopedic implants do contain nickel.

I was told that the magnet test indicates whether or not the Stainless is sanitary grade (304 or higher).

 

[Roxhambrewshed]

I must be missing something. Why does a fermenter need to be magnetic to be safe or sanitary?

Sanitary stainless explained here:

5 Things You Need to Know About Food-Grade Stainless Steel

Before you implement food-grade stainless steel in your production line, it's important to know a few things about this material first.

www.marlinwire.com

 

[hotbeer]

I used a rare earth magnet, which held itself on the side of the conical.

That's the neodymium magnet I was talking about. It'll stick to just about any common stainless steel you find.

 

[Roxhambrewshed]

That's the neodymium magnet I was talking about. It'll stick to just about any common stainless steel you find.

Thanks for clearing that up for me.
I still find it strange that it does not stick anywhere but the side wall..

 

[hotbeer]

Well I think you made your own extrapolation of what safe and not safe or what's good and not good from the articles you read.

And I'm not sure I'd agree with the way you are going about determining what is and isn't safe.

 

[mac_1103]

I was told that the magnet test indicates whether or not the Stainless is sanitary grade (304 or higher).

Why wouldn't you just ask the manufacturer what kind of steel it's made out of instead of spending $700 and doing a magnet test?

 

[Dland]

304 stainless, which is most stuff we deal with, is usually around 8% nickle, even more chromium. You don't want to ingest these, but stainless is a fairly stable material. Not many containers less chemically reactive and easy to clean, glass is one, but it has its drawbacks too.

Stainless Steel 304 - 1.4301 Data Sheet thyssenkrupp Materials (UK)

Stainless steel 304 - 1.4301 is one of the many grades that thyssenkrupp Materials (UK) supply. We supply a vast range in various forms of stainless, aluminium and mild steel. This data sheet gives you more detailed information about the chemical and mechanical properties and is available as a...

www.thyssenkrupp-materials.co.uk

316 stainless, the other most common one, is more chemically inert, but also made same ingredients in different proportions.

I'll take it over plastic any day. Aluminum is out of the question, by the way. Steel and iron vessles will likely leach flavors in beer.

 

[Bobby_M]

304 and 316 stainless has a layer of chromium oxide on the outside surface so the rest of the alloy isn't really touching your beer.

 

[KegLand]

Austenitic stainless can be mildly magnetic, depending on how it’s worked and handled. How hard did your magnet stick?

This is correct. This is definitely the case with 304 stainless steel. The more you work the stainless it will pickup some magnetic properties.

If you get a stainless steel keg and try a magnet on position A it is not magnetic. Then try the same thing at position B and it's quite magnetic.

Position A and B are made from the same sheet of stainless steel, but at position B the 304 stainless has been worked quite a lot and passed through one or two deep draw dies to make this shape.

Obviously the grade is the same as it's made from the same sheet but as you work it more it will become more magnetic. If you pay the additional 30% extra for 316 stainless this effect is far less pronounced.

 

[Roxhambrewshed]

This is correct. This is definitely the case with 304 stainless steel. The more you work the stainless it will pickup some magnetic properties.

If you get a stainless steel keg and try a magnet on position A it is not magnetic. Then try the same thing at position B and it's quite magnetic.
View attachment 815858

Position A and B are made from the same sheet of stainless steel, but at position B the 304 stainless has been worked quite a lot and passed through one or two deep draw dies to make this shape.

Obviously the grade is the same as it's made from the same sheet but as you work it more it will become more magnetic. If you pay the additional 30% extra for 316 stainless this effect is far less pronounced.

Thanks for the constructive response! Makes sense now.