ASK NDE’s TECHNICAL EXPERTS

QA

NDE’s technical team receives enquiries on a daily basis that require input from a stainless steel specialist.
Below is one of the questions that we received, together with the response from our technical experts.

Q: Which stainless steel grade would you recommend for SO2 at 400°C? 
This is for a fan for process air recirculation, with some dust present in the air.
If parts are static, can we use the 316 grade or will there still be issues with the corrosion protection?
On rotating parts we plan to use grade 253MA.

A: There are not too many choices at that temperature. Duplexes operate successfully at maximum temperature of about 300°C. You won’t be able to use 304L or 316L because of the poor mechanical properties of L grades above 350°C. Make sure you use 316 with a minimum carbon content of 0.05%
The best grade would be 310 followed by 309 or 253MA