[MW:7122] Stem material in NACE service

Dear All,

 

Could you please guide me for selecting valve stem material for NACE MR0175,  When the trim is SS 316.

 

If we refer Table.A.3 of MR 0175/ISO15156- 3: 2003

There they had clearly specified as S20910 for valve stem, pins and shaft .

 

Now some vendor is only specifying 316 (may be A479 ) and 17-4 pH.  Are this materials are correct to accept?

 

What exact material we have to take? vendor are not clear about the NACE requirement of latest edition.

 

Please advice me to select correct material.

 

Thanks in advance .

 

Regards,

Vinayak Nivendkar