What materials have been used for the pump? Normally, you request the pump manufacturer to provide you with certification for 'NACE' compliance, provided you included in the datasheet the process fluid composition, operating temperature, etc. For example, the 50 ppm might not be a problem for the Super Duplex material for the pump, but Carbon Steel at 60-70 deg C will not be suitable and will crack rapidly in operation.
However, based on your expression 'traces of H2S' the Carbon Steel pump at ambient temperature doesn't require NACE compliance.
Perhaps you should read the mentioned standard in order to realise that other components will greatly affect the so called NACE resistance (are there traces of sulphuric acid? carbonic acid? or perhaps the opposite, high pH?). Come back with some more details if you need help.
Cheers,
gr2vessels

NACE MR0103 is probably the more appropriate standard for the application. The potential for SSC is to be evaluated by the end user and MR0103 gives some guidance for such an evaluation.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04
 

Thanks for your replies.

These pumps are wash down pumps and not meant for high temperature service (max. 45 Deg C)and PH level of water will be 3 to 6.

Pump Data sheet calls for 12% Cr steel or CF3M. What I feel CF3M will solve the purpose but I am not Sure if NACE is required here?