Re: [MW:28038] RE: 28017] MIC CORROSION or co2 wet corrosion(sweet corrosion)

Dear Anasua.

I am only wandering and believe that pitting may have some other causes in addition to SRB or is there a possibility the MIC mechanism isn't reason of that damage at all, due to result of mentioned tests can not say it with high confidence and considering of all conditions.

1. I agree with you but I think the lab said it that he assumed some of hydro test water remained and  during this gap between testing and production, SRB  have done it's work.

2.yes, you're right, PH& velocity & temperature have key roles that not wasn't considered by lab and again increase uncertainty.

Now if  it was possible or tendency, what other test would you suppose to be done to increase confidence or find precise result?(with regard to other similar lines are in production.)

And what have to be done about field monitoring or preventive and remedial actions with reminding that we don't know the exact root cause?

Regards.

 

On Wed, Jul 4, 2018 at 7:24 PM, PGoswami <pgoswami@quickclic.net> wrote:

Hi Ali,

 

I assume your point is whether CO2 corrosion or MIC is the root cause  or one of the causes. We a few things to note:

1.       MIC typically occurs in stagnated condition.

2.       CO2 corrosion may happen  in both operating and stagnated condition, in presence of substantial amount of CO2 and water. Read the attached article for details. The details provided by you does not highlight any details related to CO2 corrosion, e.g. media, CO2 concentration, temperature etc.…

 

If  the pipeline contained stagnated water(without any inhibitor) for over 6 months , there're every possibilities of occurrence of MIC.

 

Perhaps discussion of  these points with the Laboratory would be helpful. To answer your question SRB (causing MIC) could be aerobic and anaerobic both. The lab has to tell what's generic form of the bacteria.

 

Thanks.

 

P.Goswami.P.Eng, IWE.

Welding & Metallurgical Specialist

Linkedin: https://www.linkedin.com/in/pradip-goswami-2999855/

Email:pgoswami@quickclic.net,pradip.goswami@gmail.com

 

 

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Ali Asghari
Sent: July 2, 2018 9:05 AM
To: Materials & Welding <materials-welding@googlegroups.com>
Subject: [MW:28017] MIC CORROSION or co2 wet corrosion(sweet corrosion)

 

Dear All.

 

We encountered to a pitting corrosion that led to loss of fluid in crude pipeline, so we prepared a sample and send it to lab.it must be mentioned that this corrosion happened after 6 months from starting of production and there is possibility for existence of remained hydro test water and the chemical injection not to start any inhibitor injection with regarding in  engineering design documents, availability of 95% inhibitor requested and warned for retained water to increase of pitting opportunity.

the lab concluded the result of this corrosion is MIC(SRB type) with doing of these tests: EDS/XRD/SRB test.
Now I have some doubts:
1.SRB or anaerobe bacteria can be survived & detected in air to reach Lab.

2.I know that to get conclusion by now is not possible but I want to know that are these tests enough or what is supposed to be done other tests to refuse co2 corrosion?

 

I have attached some results.

 

Regards.

 

 

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