17-4 PH and NACE MR 0175

[MaxCarb]

I'm selecting a material for a pump (impeller and shaft) in Sour Service as per NACE MR 0175.
My first choice is 17-4 PH above all becouse in the first period the service is not sour and for the future 200 ppm is indicated (very low).
My doubt is, with reference of section A.8 (Precipitation hardened stainless steels), which is the table to be taken in consideration for a pump? This also for other more corrosive cases.

Thanks in advance

 

[strider6]

MaxCarb

If you need to select a material for sour service you need to calculate the partial pressure of H2S and you need also to take into account other factors like the temperature, chloride conc and presence of elemental sulphur. You shall also tale into account all the possible corrosion mechanism like pitting and other localized form of corrosion.
Table A26 is for any equipment or component but 17-4PH is not listed. The 17-4PH is listed in table A27 but only for wellhead and christmas tree components (excluding bodies and bonnets), valves and
chokes (excluding bodies and bonnets) packers and other subsurface equipment.

Hope this help

S.

Corrosion Control

 

[MaxCarb]

Thanks for your reply.
My doubt regards only which table i must take in consideration concerning the impeller and shaft material of the pump.
Maybe i could take in consideration table A.28 under miscellaneous equipment or A.27.

Regards

M.