×
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!
  • Students Click Here

*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

Jobs

Weld overlay for steam corrosion
2

Weld overlay for steam corrosion

Weld overlay for steam corrosion

(OP)
Dear Experts,
We have a carbon steel "Tee" joint in steam service experiencing rapid metal loss. We suspect FAC. I did some research on this forum and found P11 or P22 would be a good substitute to reduce the metal loss. Somebody in our group suggesting weld overlay. I am looking for some advice if it will work? Thanks.

RE: Weld overlay for steam corrosion

If you have actual FAC attack, I would replace the complete Tee joint with a P11 or 1.25%Cr-1/2%Mo low alloy steel material.

The problem with weld overlay is that you will be chasing the FAC damage around the Tee section. The weld overlay with 1.25% Cr-1/2% Mo could be used as a short term fix. Ultimately you will be chasing the FAC damage to another location on the Tee.

RE: Weld overlay for steam corrosion

If you need a short term fix while you wait to install the new T then use weld overlay.
But don't delay, this is how people get killed. And now you know that there is a risk.

If you weld overlay continue the overlay well beyond the last visible point of attack. Per Metengr's caution, you will just move the erosion down stream. If the length through the T that shows damage is 24" long you need to go at least that far beyond the area.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: Weld overlay for steam corrosion

(OP)
Thanks Metengr and EdStainless. As per my understanding, continuous removal of corrosion products on CS increase the metal loss by FAC. When the Cr content is increased the Cr assists in protective film formation and thus reduce the rate of metal loss. If we do weld overlay by 1.25 Cr material (as suggested by metengr) on back half diameter of the “Tee” (where impinging or erosive effect is occurring) to the full length of the joint, would it not work? Are we not mitigating the flow effect by providing a material that can form stable film? why can't it be a long term solution? Am I missing anything here? Can you please clarify?

RE: Weld overlay for steam corrosion

1. Do you know that you still have more than enough wall thickness and the correct mechanical properties for the designed service?
2. You need to go well beyond the areas of obvious attack.
A. You need to protect the areas where the attack is slower and not obvious yet.
B. The transition from the overlay to the regular will cause some local turbulence which might lead to some localized attack.


This will be an ongoing inspection issue. You need to be prepared for that.
Replacing the T is the best route.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

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