304 Stainlees Steel or 321 Stainlees Steel 2

[kissjxp]

I have a heater which is in hydrogen service. The maximum design temperature is 520 DegC. Can I use 304 SS at this temperature? Or do I need to select stablized 321 SS for this service?

 

[metengr]

Use 321 stainless steel.

 

[strider6]

at that temperature you've to select the stabilized 321 but as you said 510°c is the max design temperature.
In my opinion you've to consider the max operating temp that usually is appreciably lower.
If your process can reach the 510°C for short time then the 304 can be used.

S

Corrosion Prevention & Corrosion Control

 

[kissjxp]

Maximum Operating is 440 DegC. Looks like 304 should not be used, right?

Do I need to specify that 321SS should be stabilized? How about the solution treated 321SS?

 

[metengr]

kissjxp;
I would not use 304 ss because you are right at the TTS C curve lower limit of sensitization for this grade of austenitic stainless steel, and the TP321 has higher allowable stress in comparison to 304 ss at this service temperature.

Yes, the TP 321 SS should be stabilized before use in service to obtain maximum corrosion protection.

 

[EdStainless]

If you used 304 it would have to L and you would be stuck with low strength and the risk of sensitization at the upper temps.
Do the right thing and use 321 or 347.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube