Inconel 625 vs Zeron 100

[NickJ67]

I have a client enquiry where a centrifugal pump specification shows a casing material of carbon steel and an impeller of Inconel 625.

Product is oily, highly saline produced water @ 105ºF. Chlorides shown as peak 145,783 mg/l, normal 78,679 mg/l trending to fall to something close to seawater over the next 10 years.
There is H2S present @ 0.002 mole fraction.

We are expected to offer progressive cavity pumps and would normally offer Zeron 100 internals and either 316ss or Zeron 100 casings (dependent on temperature and chloride content) for hot produced water. However, this is the highest chloride content we have seen - by some margin.

Is Zeron 100 likely to be suitable in this case? Inconel 625 is not something we've used before (although it's probably possible) but Hastelloy C4 and Ti are familiar.

Thanks

Nick

 

[EdStainless]

Considering that there are cases of 625 suffering crevice corrosion is seawater I think that you are fine with Z100 impellers.

What material are the bowls (diffusers)?

The casing is not an issue, though I would tend to use 9%Cr or 13%Cr in this high of Cl.
What about the shaft? It has to poses higher corrosion resistance than all of the other pump parts, it is the last thing that you want corroding. With Z100 internals it would take a Ni-Cr-Mo (C22, 59, 686) to give you better corrosion resistance.

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Plymouth Tube

 

[TVP]

It looks like this is getting close to the limit for a duplex stainless steel. Here is one reference that has some data/recommendations:

http://www.documentation.emersonpro...xBusinessUnit=Fisher Controls Valves Division

 

[EdStainless]

I am not too worried since this must be fairly deep and there will be no oxygen at all.

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Plymouth Tube

 

[NickJ67]

Thanks for your replies. I don't have any information on oxygen levels, but as the water is coming from way down they are likely to be very low as already said.

The pump we will be offering is actually a progressive cavity not a centrifugal (due to low shear characteristic giving less oil emulsification) so more internal parts than a centrifugal, although only three (rotor, coupling rod and driveshaft) are process wetted. All are fairly simple shapes with machined finish and minimal corners/crevices. We would normally make all three from the same material. Wetted casing parts (suction housing, discharge housing and seal hosing) could be 316 / CF8M (cast) or Zeron 100 (fabricated). Pump rotation speeds are quite low - certainly less than 400 rpm.

Regards

Nick

 

[seniorprojectmanager]

MR0175 Part 2, Paragraph 7.2.1.2 Figure 1 Regions, and also Para 7.2.1.4
Please help me make some sense of the conflicting information. According to the latter para, A.2 materials can be used in all of the regions. When looking at the Table A2 (page 21), it lists carbon steel pipes in API and ASTM grades. If we can use carbon steel for all conditions, then why are all other CRA and SS tables described. To further confuse, Page 24 (para A3) gives information on materials specific to Region 2 and 1. This is in contradiction to previous given statement. Also, where do we go to find materials suitable for Region 3?

Thanks guys/gals

 

[SJones]

Apart from hijacking the thread, you do realise that CRA materials are dealt with in Part 3 and that the versions are now at 2009? Of course you can use the appropriate carbon steel for "all conditions" if all you are worried about is sulphide stress cracking. However, carbon steel in wet H2S environments also tends to develop nasty holes which is why people move on to selecting CRAs!

Steve Jones
Materials & Corrosion Engineer

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