×
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

API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

(OP)
API 650, Figure 5.7a, detail b, indicates that the corner-corner weld of the flange to the neck shall be the thickness of the thinner member joined however, Figure 5.12, detail b, indicates that the corner-corner weld of the flange shall be the thickness of the thinner member joined, with a max weld of 1/2 inch.

Wouldn't the same apply to both? Is the fillet limiting note mistakenly absent from Figure 5.7a, detail b? Or, is the note mistakenly placed in Figure 5.12, detail b?

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

Hi CSKCJK,

I know this standard but never designed a tank, anyway, pictures refer to different structures, the first a manhole (same weld bevel for the entire perimeter), the second a flush type cleanout fitting (different weld bevels for top and bottom).
Furthermore, the shapes and positions of the openings are different, so I would definitely expect differences in design.

Maybe you can find a clue in the related paragraphs?

Regards,

Stefano

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

I do not believe that the 1/2" limitation is missing from Figure 5-7A. Note 2 of Figure 5-7A requires that the gasketed surface shall be machined. This makes weld distortion of the flange face inconsequential, since it will be machined flat. The flush clean out internal fillet weld cannot be made with the cover plate bolted to the flange as the external fillet weld can, and could be distorted by too heavy a weld. The external weld distortion will be controlled by the presence of the cover plate while welding and the PWHT after fabrication.

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

(OP)
Why doesn't the standard (API 650) recommend the face of the flush-clean-out (FCO) flange be machined? We machine ours. Do you? How is it different from a manway flange?

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

"How is it different from a manway flange?"

Manway flanges are round, flush-clean-outs are not. Manway flanges have ring type gaskets, flush-clean-outs have full face gaskets. Flush-clean-outs are subject to rotation due to interaction with the vessel floor (and possibly anchor bolts), manways are not.

How do you machine finish your flush-clean-outs? When do you perform the machining? Without a phonographic finish, how do you determine that you're not making the seal worse than a non-machined surface?

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

(OP)
We use the same full face gasket with both manway (MH) and FCO, and we don't apply a phonographic finish- we apply a flat machine surface with 125 Ra. We have the FCO, and MH machined on a milling machine. We machine the FCO after PWHT. I take it you guys don't machine your FCO?

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

I will restate what I believe to be your question:

Is machining of FCO flange faces required by API 650? No.

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

(OP)
Actually, what I'm questioning is- if 1/2 inch fillet is enough for the flg-neck weld of the FCO, why isn't it enough for the same weld of the manway? Additionally, based on the point you raised regarding weld distortion, I'm curious, does anyone actually sell FCO that isn't machined? And, what's the level of comfort/experience that the FCO does not leak?

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

Your question is valid, and I don't have a direct answer. I could bring it up at the next committee meeting if you would like. There are some things to consider, though.
1) Many manway necks are less than 1/2" thick, so the difference is only applicable when the thickness of the shell and reinforcing plate is greater than 1 1/8".
2) A FCO has more weld length per area of opening than a manway. I would have to calculate the percentage difference, but that could be a reason that the limitation does not exist for manways.

RE: API 650, Figure 5.7a, detail b, vs. Figure 5.12, detail b

I don't see FCO leaks and with all the bolts I can't see it leaking. I recently saw a 36" manway whose flange I measured and was warped by one-eight of an inch and it did not leak. It is curious however, and I have send API to remind them that the new figure 5.12 is missing all its notes.

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