corrosion rate on carbon steel

[hcjulien]

Hi,

I'm searching for a approximate corrosion rate on carbon steel (SA-516 Gr. 70) in contact with 5 to 7% of H2S and Hydrogen at 70F/50 PSIG.

Thanks in advance,

hcjulien

 

[strider6]

The fluid is a gas or a multiphase? Is there any water?

S.

Metal Corrosion

 

[hcjulien]

It's a gas without water

 

[gr2vessels]

C'mon strider, tell him to read the definition of corrosion. You need oxygen and an electrolyte on top of the carbon steel to corrode;- remove any one of the components and there is no corrosion. No oxygen, no corrosion, no water, no corrosion, no steel, no corrosion. Simple.
Cheers,
gr2vessels

 

[unclesyd]

gr2vessels,
Your definition of corrosion doesn't work in all cases. Corrosion of steel isn't tied to strictly aqueous, thought this is most prevalent form.
We have processes that completely destroys steel by actually putting the steel in solution, not a water solution. Another part of the process would take a material, SS, that was perfectly suitable for holding a boiling aqueous solution and the minute you dehydrated the solution and melted the solute it would dissolve the SS in a heartbeat. The temperature was 260C and there was no analyzable water or oxygen.
The corrosion one metal by another, molten.

 

[SJones]

gr2 - try getting a look at API 571. You will find that there's more to corrosion than water. The thread originator may have had a concern regarding high temperature hydrogen attack (HTHA) and/or sulphidation. Fortunately, at 70 deg F, these two mechanisms would not be active and, with no water, then the expected corrosion rate under the stated normal operating conditions would be negligible.

Steve Jones
Materials & Corrosion Engineer

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

 

[gr2vessels]

gents,
Julien has had a specific question, not a generic one. As Steve has noted, at the given temperatuer and pressure, non of the H2S and Hydrogen would affect the mentioned boiler plate. I'm merely pointing that a bit of the research prior to asking this specific question would have been helpful to Julien, particularly when he was aware of the gas only environment, at low pressure and at about ambient temperature. Obviously, every engineer should have some basic understanding of corrosion, in order to be able of reading/understanding NACE, API and other related publications and standards. A straight answer of black or white would not help, nor would encourage him to read about this vast topic. I stand however, corrected for over simplifying the "corrosion" to a mere crust of rust on the boiler plate.
Cheers,
gr2vessels

 

[strider6]

gr2,

I don't think that "tell him to read the definition of corrosion" is a good approach if someone ask u a question on corrosion.
I'm a corrosion engineer and i think that i've been asked this question at least two times a weeks in the last 4 years..
There are only few engineer even in an engineering company that have a background on corrosion, even the fundamental concepts..
I've never said "read the definition of corrosion and go away...", ..This is not my approach maybe your is different...

S.


Metal Corrosion

 

[unclesyd]

For edification of all. Even I was taken aback by complexity of the definition. I reckon you use it cafeteria style, just pick and choose.

http://corrosion-doctors.org/Principles/What-is.htm

 

[gr2vessels]

I have to admit that I didn't take the best aproach in my post, despite the best of my intentions. I have a bit of history of success with younger people in helping them to clarify questions, by encouraging them first to read about the topic and then put their ideas in the right order. The answer came as a consequence of their their own study. It never helped anyone a straight answer to the question without clarifying the background. Waste of time for both parties. In fact, I have seen too often contradicting answers in this forum, leaving the poor poster more confused than earlier.
As I stand corrected, it seems that I'm wrong to encourage the younger ones to do some research before posting a question.
On the other hand, is it the role of this forum to provide quick fixes to someone or to give him/her the oportunity to learn by opening them a wider door than a simple answer. I support the later.
cheers,
gr2vessels

 

[SJones]

gr2 - don't hammer yourself too hard. There's 700,000 people on this site and each one will have a different approach. I can sympathise with the 'research first' part - it's how I work when I have a problem (it also helps with framing a question on here correctly). Our replies are not meant as personal rebuffs; more of lending a guiding hand. Keep up your good work.

Steve Jones
Materials & Corrosion Engineer

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