Water is the key component that you need to quantify. Zero water - no discernible metal loss. What is the hydration state of the gas? You also need to fully define what you mean by “last”.

https://www.eng-tips.com/search.cfm?q=Corrosion+ra...

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

Oh how long will it last, as in how long will it be suitable for transporting the sour gas? Are we talking 2-3 years or less? or more like 10 - 20 years or more?
2 scenarios regarding water content:

- Extremely low 0.0001% H2O to no water presence
- low 1% H2O

Is there any difference?

Thanks for the corrosion rate determination search thread, found some great threads there :)

The pipeline will "last" as long as there is sufficient material to provide structural integrity for the design conditions pertaining at the time of consideration. Predicting how much material will be lost over a required target lifetime is far from being a science.

This is the best that you will get for free: https://www.icmt.ohio.edu/web/software/public/free...

It won't go to 250 bar, so follow their pop up advice regarding a 10% overage on partial pressures (which you now know all about)

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

Is your pipe made to "sour service"?

This sort of H2S level is commonly regarded as sour.

But as S Jones says free water is your crucial element.

The issue you will face is pitting corrosion which is a bit random. If you can't control free water then prob 2 to 5 years.

But you really don't want to be leaking H2S gas.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

@SJones thank you for pointing me to the software Freecorp 2.0 I will try to use it effectively!

@LittleInch I just checked, there wouldn't be any water in the pipe and yes, the pipe is made to "sour service"

Hmmm, most fittings, valves and tubes for sour service I find are 316 ss. Any idea or estimation of what concentrations of H2S can those fittings, valves and tubes tolerate?

I already sent these companies an enquiry but thought I'd ask here too :)

Thank you guys for your help :)

This is why you need to employ experienced materials engineers to do this work for you who are in full knowledge of what your system is and how it works.

But this strikes me you're doing this the wrong way around. You design to a set of design parameters including design life.

Anticipating failure before the end of the design life is a mugs game. Nothing in this type of engineering is that precise and like I said, 100ppm H2S, you really don't want that coming out of your pipe, especially at 250 bar.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

This is not looking good. In another thread you stated that you were an intern. You should be working under the guidance of an experienced engineer, not an internet forum

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

To clarify my position. Yes I am an intern, I am just trying to find answers (or direction into how to find answers) to those questions and present my findings (if any) to my supervisor, hence I am searching in engineering forums and look into many research papers.

OK - so have you learnt enough to reframe your question regarding the life of the pipeline?

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

To answer your question, I think a better way of asking the previous question is:
What is a good approximate of the life of API X52 pipeline transporting sour gas given the following conditions

---

Actually using NACE-MR-0175 I think I got a good approximate of the max H2S concentration allowed for stainless steel 316 fitting, valves and tubing that complies with NACE. Using the equation you gave me before
pH2S = Total pressure of system x H2S composition

I got max H2S 4000ppm. If you can please take a look at the attachment, is the deduction I made right?

• https://files.engineering.com/getfile.aspx?folder=db0d1458-aa19-432a-952f-e

How about this: “what would be time to end of life of a pipeline with a starting wall thickness of X mm, and end of life being taken as reaching the minimum allowable wall thickness for a pressure of Y bar, given the following fluid conditions, composition, and flow rates?”

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

The pipe can potentially last forever if you take into consideration maintenance or apply mitigation, assuming your pipe in manufactured to sour service specifications (NACE, or ensuring hardness levels). I've operated pipelines more sour than that that are >50 years old with no failures. That difference in water will make a huge difference in terms of internal corrosion. I see you've made a basic calculation applying a corrosion rate as you should, but does your company have maintenance / mitigation requirements for pipelines or sour service pipelines? Rather than just leaving them to corrode? It is extremely difficult to predict pitting corrosion, which the general Dewaard Milliams based equations don't really do, but a general rate, pitting rate will exceed that if conditions set up for it.

"Engineering Tips: --- Unpaid training for confused Engineering Interns since 1995 !!!"

MJCronin
Sr. Process Engineer

No MBA necessary, but it helps

Steve Jones
Corrosion Management Consultant

www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.