Ni Resist or 12% Cr for Pumps Material with brackish water?

[Vinzzzz]

Dear all

I have a question about best solution to be done for pumps material selection for brackish water.
The total content of clorine ions in the water is about 1660 ppm, PH 7-8, 7000 ppm of CaCO3 and is saturated in oxygen.

According to API 610 matertials suitables for water services similar to brackish (Foul water, reflux drum water, water draw, and hydrocarbons containing these waters, including reflux streams) are S3 (NI Resist) and C6 or S6 (both 12% Cr).

The question is: are Ni resist iron better than 12% Cr for this service? Could the 12% Cr subject to pitting corrosion for the high content of clorine ions (1630 ppm)?
In case of the two material are both acceptables wich is the best solution in therms of cost saving?

For me the 12% Cr is not a suitable material due to the presence of Cl- ions and oxigen (1630 ppm for me are too many also for an AISI 316) so the best could be duplex.
Obviuously the selection will be oriented on Ni-resist materials. Could you, please, help me on this matter?
Thanks for all

Best regards
Vincenzo Saviello

 

[micalbrch]

A 12% Cr will fail as you already mentioned. A Ni resist will work but is not cheap. Depending upon your pump type and size a rubber lined pump is an option to look at. I'm sure it is way cheaper than a Ni resist pump. The chemical resistance of rubber lining against Chlorides is excellent.

 

[PBroad]

If cost is the primary consideration why not use a peristaltic hose pump, its 100% lined

 

[SJones]

The attachment might be of some use.

Steve Jones
Materials & Corrosion Engineer

http://www.oilandgaspeople.com/cv/11499664

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

 

[EdStainless]

While a 22% Cr duplex would work well Ni-Resist is much easier to cast and machine. Those are the two options that I would look at for this application.

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