×
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.

Students Click Here

4130 for wet CO2 and H2S service

4130 for wet CO2 and H2S service

4130 for wet CO2 and H2S service

(OP)
just looking for material suggestions for a gaseous environment operating at 300PSI.

it's currently about 50% CO2 and 50% H2 were processing, with only around 50PPM H2S.  the gas stream is also humid, 100%RH. temperature is around 60C

considering we're making pressure vessels out of the material, it must be manufacturable.  thinking instead of the mild steel, maybe 4130 might be a better option.

we can't have any rust form on the inside of these vessels.  it messes with our valves.
Replies continue below

Recommended for you

RE: 4130 for wet CO2 and H2S service

Have you considered a polymer coating on the wetted surfaces?

RE: 4130 for wet CO2 and H2S service

(OP)
hush,

by polymer coating i'm assuming you mean a powder coat, or a polymer lining.

i'm uncertain of how you'd line these as vessels.  powdercoating the inside could be uneven and would require QA.

RE: 4130 for wet CO2 and H2S service

SAE 4130 with small additions (~0.5%) of molybdenum are often used in H2S environments.  Hardness should be kept on the low side (26 HRC maxmimum) in order to minimize susceptibility to sulfide stress cracking.

Regarding your question about coatings, you are correct, iron phosphate really doesn't offer much corrosion protection.  Zinc phosphate and zinc chromate are both good pretreatments when used in conjunction with a polymer coating.  Epoxies and polyurethanes are typically applied over these pretreatments, by any number of methods-- electrostatic spray, cathodic electrocoating, etc.  I am not familiar enough with H2S to know if it seriously degrades either of these polymers.  I would talk to a good paint supplier (PPG, BASF, etc.) about compatibility and potential application methods.

RE: 4130 for wet CO2 and H2S service

(OP)
the compatibility info i've got suggests typical polyester-epoxy powdercoating blends would be adequate for H2S environments.

i'll chat with our vendors to determine if coating the inside is a possibility.

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! Already a Member? Login



News


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