Stainless Steel 300 series

I am specifically looking at SS 303. How well this will do in HVAC system dealing with water. I know majority of SS being used in HVAC uses 304 or 316 grade.

303 has poor corrosion resistance because of the inclusions that are designed to improve machinability.
305 is designed to offer better formability.
Are you going to weld? If so then you need low C.
What product form do you need? Tube? Bar? Plate? Sheet?
It matters as not all of these alloys are available in all forms.
You can't get 303 tubing for example.

EdStainless said:

303 has poor corrosion resistance because of the inclusions that are designed to improve machinability.
305 is designed to offer better formability.
Are you going to weld? If so then you need low C.
What product form do you need? Tube? Bar? Plate? Sheet?
It matters as not all of these alloys are available in all forms.
You can't get 303 tubing for example.

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this is just a product I'm getting for HVAC. 305 can be tough to find. I would think 304 would be a good equivalent to 305?

How much forming are you doing?
Is this tubing?
Well annealed 304L should work.

Here is a nice publication related to stainless steel used in fans.

Stainless steel doesn't like chlorine, not sure what kind of water you are referring to.

Deals with water? Is this a chilled water system? Ducting with wet air? Throw us a bone. If you put some thought into making the plastic to metal connections (no metal on plastic threads!), CPVC works remarkably well for chilled water systems.

If your HVAC system handles just freshwater and mild conditions, 304 is sufficient and cheaper than 316. if water quality is variable (e.g., contains salts) or longevity is critical, 316 is the better grade. Avoid 303 for water-contact parts—it’s better suited for dry, machined components.

In my realm of industrial machinery 316 is the king and 304 is also used but only rarely because its theoretical cost savings are gobbled up by its lower volumes. (It would not be such a wash if we were buying mill runs) Other grades of 300 series are very rare occurrences in my world. So if you think 303 is going to be cheaper, confirm that before you write this in ink.

There is a lot more free information on the Internet than you suggest. There are people out there who want to sell it and will provide useful information. But it will take some time to make phone calls and see what grades are actually stocked in which shapes and sizes. That's when you find out the real story.

Neither 304L or 316L will like static conditions for extended periods.
And if there is no biological control you will have issues also.
The trend today is to use duplex SS.
In place of 304 or 316 they use 2101.
It has better pitting resistance than normal 316, it is much stronger (allowing thinner walls), and the price is more stable as the surcharges are very low.
If you need better corrosion resistance then you move up to 2205.

duplex 2205 is very common used in industrial applications now days ,and you can find out of duplex 2205 stock very easy as 316L, but the price is a little higher than 316L, actually there is nearly no stock of 316 grade in worldwide market, reminder they are different grades between 316 and 316L.

FrancoisY said:

Hello,

With Stainless Steel 300 series, are there much difference in material properties? with the increase in values (e.g. 301, 302, 303, 304, 305 etc.) what deciphers them for your needs. I do not have access to expensive websites or books. Any tips will help.


Thank you

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data sheets are readily available on line from
suppliers and manufacturers. look at the suggested properties and applications and addition to the previous suggestions.
your not clarifying the application.
there is precipitation stainless as well.
then in chemical tanks there are coatings used to line tanks.