×
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

Flush patch repair
3

Flush patch repair

Flush patch repair

(OP)
A company in California holding an R1 certificates will repair an epoxy lined pressure vessel with a 2-inch diameter hole on the shell. Aside from the hole, there are corrosion damage (pittings)around the bottom of the distributor. Question:

1. The hole would be repaired by flush patch and inspected by means DPT on root and final passes in lieu of hydrotest. Is it OK to DPT the patch as long as the AI is informed?

2. The pittings around the bottom of the tank might have gone to some extent that the wall thickness has reduced considerably low. What is the remaining plate wall thickness that should be considered for replacement?

Design pressure: 75 psi
Design Temperature: 150 Deg F
Corrosion Allowance: None

Thanks in advance   

RE: Flush patch repair

AI should be informed before any repair or alteration required a "R" stamp.  No RT or UT?

remaining wall thickness is dependent on what the calculations call for as minimum thickness.

RE: Flush patch repair

Quote:

1. The hole would be repaired by flush patch and inspected by means DPT on root and final passes in lieu of hydrotest. Is it OK to DPT the patch as long as the AI is informed?

Informed? You mean having the AI review and approve your repair method per the NBIC. Regarding volumetric examination, this depends on the original NDT of the vessel and service conditions. If the welds were spot radiographed - I would see no reason to use RT or UT for a flush patch repair and use surface NDT methods. If the vessel was radiographed 100%, you would most likely need to have the flush patch welds subject to the same level of NDT (my professional opinion only). Your AI will make the final call.

For determining remaining wall thickness to retain pressure I would require API 579 to rely on my justifcation for not having to restore wall thickness. Not an easy task but can be done.

 

RE: Flush patch repair

In response to #1:  Make sure no RT is listed on the data report.  NDE methods for repairs must be per the original code of construction.  If there is no RT, then DPT is acceptable with the AI's agreement.  Also check for any PWHT requirements.

In California, any alternatives to NDE or PWHT require not only permission from your AI, but also permission from State of California.

In response to #2:  Ditto on vesselfab's comment, with an additional comment that this will also require DPT per the original code of construction (assuming it's ASME Sec. VIII Div. I)

 

RE: Flush patch repair

I guess I am old fashioned.

If I was welding in a window (flush patch) in the side of a vessel, and not doing a hydrotest, I don't really care what the original data report says, I am going to 100% RT the weld.

sorry

just the way we do things.

RE: Flush patch repair

(OP)
Thanks for the help guys.

RE: Flush patch repair

AI has to approve the repair and inspect results.
NDE in CA will be per AI approval and will depend of the
original construction.-
The vessel use is important for the AI to make a decision on the method of testing.
good luck



 

 

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