304 versus 316

[nickt1960]

I don't have cryo experience and was wondering whether I could use 316 in lieu of 304 for low temp applications down to -196 C? I am trying to ban all 304 from our site for pitting resistance reasons but have been told we need 304 to achieve the required properties down at these temps. As far as I am aware 316 would be equal to the task?

 

[iainuts]

316 is generally considered to be a better grade of austenitic stainless, regardless of temperature. Go ahead and use it in cryrogenic applications. Material prop's are roughly equivalent to 304.

 

[dcasto]

316 typically costs more? Thats why 304 is most common. I can understand a delivery time being a factor on some specialty items.

 

[Qina]

I quite agree with iainuts. As previous experience from my work indicated, SS316 is capable for most of the cryogenic applications (low to 196 degC), such as liquid nitrogen.

 

[EdStainless]

The only time that I have seen 316 used was when there were external corrosion issues. Both will have good properties at those temps.

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Plymouth Tube

 

[020100]

316 has better magnetic properties due to phase transformation @4.2K. It costs more (~20% more).
People use more 304L these days

 

[unclesyd]

304 has slightly better properties than 316 at you temperature so you have a toss up. Most of the data and examples I have use 304 and 304l as examples for vessels down to -425F.

 

[nashof]

For cryogenic service I agre with unclesyd: 304 has better properties than 316, but the difference is so small, that I think that the main reason which makes 304 to be used for cryogenic service is the money.
For cryogenic service (typical LNG or LN2) corrosion is not a problem (usually) so both of them are OK. If you have an important corrosion factor, or if you think the difference in money is not a problem in your case I would use 316, if not I would use 304.

And.. what about 304 vs 304L (or 316 vs 316L)??
I know the difference in carbon percentage, with the corresponding problem for welding (not so big actually) but, do you think one of them is better for cryogenic service??
Personally, if there are not other reasons or data in the process data sheet I use to select SA-240 304, and it works perfectly, but which are your opinions?

In cryogenic service pressure is not usually very high (for example in a LNG plant the highest could be 20barg in the recondenser) and so thickness are not very very big, so welding is not extremely difficult (I wouldn't use 304 for a reactor with a 200mm wall!).

 

[belowzero]

Either I'm missing something or the application has not been stated!
Surely all of the above discussions should take into account the aplication, only nashof (Mechanical)has indicated an application preference. The physical loads and form of manufacture are also an indicator to whether one or other of the materials is suitable. For example neither should be used for high torsional loads on say a valve stem.

Below Zero