Material Selection For Corrosive And High Chlorides Fluid
Material Selection For Corrosive And High Chlorides Fluid
(OP)
Hi,
I am currently working on a gas processing plant offer in which the maximum CO2 content in the raw gas shall be taken at 25 mole% and 15 PPM of H2S. The chloride level in water is up to 14,500 mg/L. Operating temperature of the fluid is 250 F and operating pressure is 1186 psig. Client has asked to select appropriate / suitable CRA (corrosion Resistant Alloy) metallurgy of material. Can anyone help me in the selection of MOC based on the above mentioned conditions of fluid? Please note that at downstream there is an evaporative cooler which will lead down the temperature up to 135 F. Please guide me regarding the MOC for upstream and downstream of that evaporative cooler. Can i go with SS 316 on theses fluid conditions?
Regards
I am currently working on a gas processing plant offer in which the maximum CO2 content in the raw gas shall be taken at 25 mole% and 15 PPM of H2S. The chloride level in water is up to 14,500 mg/L. Operating temperature of the fluid is 250 F and operating pressure is 1186 psig. Client has asked to select appropriate / suitable CRA (corrosion Resistant Alloy) metallurgy of material. Can anyone help me in the selection of MOC based on the above mentioned conditions of fluid? Please note that at downstream there is an evaporative cooler which will lead down the temperature up to 135 F. Please guide me regarding the MOC for upstream and downstream of that evaporative cooler. Can i go with SS 316 on theses fluid conditions?
Regards





RE: Material Selection For Corrosive And High Chlorides Fluid
So, you will have a pH of about 3, 15,000 ppm Cl and 250F.
You could use alloys like 4565, AL-6XN, 654SMO, and they will be borderline.
That leaves you with a "C" type Ni alloy (C22, 686, 59) or Ti (but not CP, it will need to be an alloyed grade such as 12 or 16).
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P.E. Metallurgy, Plymouth Tube
RE: Material Selection For Corrosive And High Chlorides Fluid
Ive been asked such questions every now and then, but have always forwarded them to experts. The subject itself however is interesting to have some basic understanding about.
RE: Material Selection For Corrosive And High Chlorides Fluid
http://www.outokumpu.com/en/tools-and-downloads/to...
And look at their corrosion guide. If you request a print version it has bunch of support information in it.
There are also many good papers at
http://www.nickelinstitute.org/ look in the Knowledge base
Good luck, Ed
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P.E. Metallurgy, Plymouth Tube
RE: Material Selection For Corrosive And High Chlorides Fluid
http://www.nickelinstitute.org/TechnicalLiterature...
Since there is H2S around, ISO 15156-3 will also apply which will also give application limits of materials in terms of the key variables: temperature; partial pressure of H2S; chloride ion concentration; pH. You might like to work with design pressure to calculate the partial pressure of H2S (Note: design pressure is the process design pressure and not the maximum rated pressure of the class).
From these two documents, you might identify 22Cr duplex stainless steel as a candidate.
Steve Jones
Corrosion Management Consultant
http://www.linkedin.com/pub/8/83b/b04
All answers are personal opinions only and are in no way connected with any employer.
RE: Material Selection For Corrosive And High Chlorides Fluid
RE: Material Selection For Corrosive And High Chlorides Fluid
The Cl level is not a very big factor, but pH=3 and 250F are what will drive this.
Take another look.
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P.E. Metallurgy, Plymouth Tube
RE: Material Selection For Corrosive And High Chlorides Fluid
Regards
Krishn
RE: Material Selection For Corrosive And High Chlorides Fluid
If you look at the curves carefully you will notice that the duplex alloys suffer far more impact from the presence of H2S than the austenitic alloys do.
I cannot imagine trying this with a 22Cr duplex.
I wouldn't try with anything less than a Ni-Cr-Mo "C" alloy, unless the cost of failure is very low.
Once you reduce the temperatures alloys such as 2205 or 825 become very good candidates.
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P.E. Metallurgy, Plymouth Tube
RE: Material Selection For Corrosive And High Chlorides Fluid
As per dalton's equation, the partial pressure will come around 296 only as per the current operatin pressure. Also the design pressure is not given.
Can you please explain? I would like to know from you. Please help.
RE: Material Selection For Corrosive And High Chlorides Fluid
And based on curves and experience I know that in room temp high pressure systems carbonic acid will reach pH of 3.
The exact value does not matter. It will be less than 5 for sure, so you need to assume that condition can be worse (because they always will be).
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P.E. Metallurgy, Plymouth Tube
RE: Material Selection For Corrosive And High Chlorides Fluid
Thus 22Cr could be a candidate material, but as the Nickel Institute document states, "The reader is advised to consult the latest test data and ISO 15156 corrigenda or make an evaluation based on testing for the specific application."
Steve Jones
Corrosion Management Consultant
http://www.linkedin.com/pub/8/83b/b04
All answers are personal opinions only and are in no way connected with any employer.
RE: Material Selection For Corrosive And High Chlorides Fluid
ClSCC can be occurred and the factors which influence the onset of cracking are concentration of chloride, temperature, stress level, solution & pH. Duplex stainless steels are not immune to ClSCC but show an increased resistance to cracking. H2S has a synergistic effect with chloride on ClSCC of duplex SSs.
Higher nickel alloys such as the “superaustenitic” grades and Inconels/Incoloys and alloys approximately >45% Ni (Hastelloys, Monel) are preferable to be used in your case. If there is cost restraint you can think about cs pipe with an internal alloys cladding.
You should also ask your client to concern about the cooler's material if condensation will take place there.