×
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

Repair of corrosion hole on nozzle

Repair of corrosion hole on nozzle

Repair of corrosion hole on nozzle

(OP)
I have a storage tank with a corrosion hole on the neck of a manway nozzle located at the base of the tank.

653 tends not to give much guidance on repair methods so I'm wondering what might be the best course of action might be. The corrosion hole is small (1" x 1") and the surrounding area has good metal remaining.

I'm thinking of cutting out an area of the nozzle and placing a patch in. Is this right, and if not, what other courses of action might be appropriate?

Thanks,

Devin

RE: Repair of corrosion hole on nozzle

The most cost effective solution may be to cut the nozzle neck before the pentration and replace the neck and flange. This would be much easier than a button weld patch.

RE: Repair of corrosion hole on nozzle

fegengush has a good point, but a small diameter butt patch could be feasible as well, and with less welding. A few considerations for a welded repair can be found in Part 2 of ASME PCC-2 Repair of Pressure Equipment and Piping, though be aware that there is no Article which specifically tells you how to fix it. If you choose to put a butt patch in, it'll provide some general guidance, along with other possible repair techniques such as a fillet welded lap patch which could (and I have) be placed on the inside.

RE: Repair of corrosion hole on nozzle

How thick is the manway neck? Is it one continuous rolled plate with a butt-welded long seam? Or is it an older 12c style with the two press-formed halves with one big circ-seam joining them?





RE: Repair of corrosion hole on nozzle

I would agree with Fegenbush, best to replace the manway. While API 653 does not directly address holes in the necks of manways it does state that the minimum size of a shell patch plate shall be 12" (9.2.2.1). It will also be difficult to meet weld spacing requirements (Fig 9.1). These don't specifically address necks but they are good starting points to consider when evaluating your repair.

RE: Repair of corrosion hole on nozzle

The neck is not on the pressure boundary of the tank and clearly has no relationship to the global failure of the tank. What's wrong with using a backup strip, welding the hole shut, get complete penetration and fusion, MT the final both sides, grind it flush and call it a day? Not much worse than buttering a shell gouge and grinding it flush. "Where grinding to a smoothly contoured surface will result in unacceptable shell plate metal thickness, the shell plate may be repaired by deposition of weld metal, followed by examination and testing in accordance with 12.1.8." This is a bit more extreme, but the downside risk is a leak, not catastrophic failure of the tank. I'd even go for a lap patch, if this is unpalatable.

RE: Repair of corrosion hole on nozzle

Prepare a hole and install a solid round bar, full penetration weld.
Regards
r6155

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