INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

HTHA and H2-H2S Corrosion

HTHA and H2-H2S Corrosion

(OP)
Hello my dear Fellow members,

I am daily coming across both HTHA and H2-H2S Corrosion material review , and I do use the Nelson's curve and Couper Gorman curves for my selection. The question coming to me daily is that why don't we verify HTHA in an H2S containing environment? And Today my question came to the interest since I have met such an interesting service. In the current service (which contains approx 8% H2S and 710 psi H2 partial pressure), CS is suitable if I consider couper Gorman curves, but when I cross checked with HTHA, then I can't use CS, rather I must go for at least Low alloys.

What is your opinion in this? Is there any alleviation of damage by the presence of H2S in a Hydrogen containing environment sometimes? In my experience, I feel presence of H2S aggravates the damage.

this is wonderful for me, hope for you too. So give me some advise.

Cococa

RE: HTHA and H2-H2S Corrosion

They are two different degradation mechanisms: one occurs at the metal gas interface, the other occurs within the metal itself. It is possible that the generation of the corrosion product from the reaction at the metal gas interface could influence access of the hydrogen to subsurface regions, thus influencing the rate of development of HTHA. Why not try a literature search?

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: HTHA and H2-H2S Corrosion

(OP)
Jones, Great to see your reply.

I have already done many searches, and I could not find a convincing answer on this. I need to fix my philosophy of material selection in judging HTHA on H2-H2S service also. It's not a walk in the park for me even many feel otherwise.

Cococa

RE: HTHA and H2-H2S Corrosion

If you have no reliable objective evidence for a reduction in degradation severity, then assume the worst case and determine what the value implications are. The technical safety specialist then has something to work with for demonstrating ALARP.

http://www.hse.gov.uk/risk/expert.htm

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: HTHA and H2-H2S Corrosion

For what it's worth ; I can promise you that Al Couper never considered hydrogen attack when developing corrosion curves.

RE: HTHA and H2-H2S Corrosion

Dear Cocoe
you ve got 2 different types of damage here :
- generalized corrosion due to sulfur species at high temperature (couper & gorman, McConnomy, other curves from API 939-C)
- hydrogen attack (Nelson)

you ve calculated that you can control generalized corrosion with selection of carbon steel, but it cannot be finally selected because it is not suitable regarding Nelson curves.

thus you should now evaluate the material induced by Nelson curves (low alloy steel) and check if it is suitable regarding couper&gorman (it will if carbon steel is)

I hope it helps
regards

RE: HTHA and H2-H2S Corrosion

Cocoe,

if anything H2S will make HTHA worse since it acts as a dissociating agent, leading to the formation of atomar hydrogen from H2 which can diffuse more easily into the metal. Additionally the H forming in the corrosion reaction btw.H2S and the steel may diffuse into the steel.

Daniel Breyer
Inspection Engineer

http://lnkd.in/dFcQA-w

RE: HTHA and H2-H2S Corrosion

quote :
DBreyer (Materials)
Cocoe,

if anything H2S will make HTHA worse since it acts as a dissociating agent, leading to the formation of atomar hydrogen from H2 which can diffuse more easily into the metal. Additionally the H forming in the corrosion reaction btw.H2S and the steel may diffuse into the steel.

end quote

true that H2S enhance HTHA but then I think DBreyer maybe make a confusion between higth temperature sulfidation and wet H2S cracking processes ?
H2S is poisonous for atomic H recombinattion thus increase hydrogen permeation rate in wet H2s environements

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close