Anchor chair gusset welded over the skirt long seam
Anchor chair gusset welded over the skirt long seam
(OP)
Dear all,
Vessel shop asked our approval after the fact that they welded anchor chair gusset over the skirt long seam as shown in the attached sketch. Is it acceptable ?
Vessel shop asked our approval after the fact that they welded anchor chair gusset over the skirt long seam as shown in the attached sketch. Is it acceptable ?





RE: Anchor chair gusset welded over the skirt long seam
At this point you're down to good engineering judgment and/or project specifications.
RE: Anchor chair gusset welded over the skirt long seam
The main stress from an anchor chair is in the vertical direction, I believe, as is the stress in the skirt.
RE: Anchor chair gusset welded over the skirt long seam
RE: Anchor chair gusset welded over the skirt long seam
Regards
r6155
RE: Anchor chair gusset welded over the skirt long seam
RE: Anchor chair gusset welded over the skirt long seam
Regards
r6155
RE: Anchor chair gusset welded over the skirt long seam
RE: Anchor chair gusset welded over the skirt long seam
Regards
r6155
RE: Anchor chair gusset welded over the skirt long seam
Has anybody stopped to wonder whether or not the anchor bolts in question are actually embedded in concrete? Does the possibility exist that they are thru bolted on a steel structure?
Surely, all vessels are alike, none are unique, and the Process Industry Practices (the PIP's) cover every possibility for every vessel ever built for every industry?. Sheesh. My company is a member of the PIP organization, and I can freely use the PIPs for our vessel standard drawings. But most of them we don't use. Does that make our standard drawings "wrong"?
Is welding over a long seam on a skirt ideal? No, I'd say it isn't. But it is not the end of the world either.
RE: Anchor chair gusset welded over the skirt long seam
RE: Anchor chair gusset welded over the skirt long seam
Please see ACI 318 edition 2014 Chapter 17
17.2.1.1 Anchor group effects shall be considered wherever
two or more anchors have spacing less than the critical
spacing as follows:
Regards
r6155
RE: Anchor chair gusset welded over the skirt long seam
As for anchor bolt spacing, we apply 5 x bolt diameter as the minimum for concrete support. Less than 5D is not desirable, but can be achieved by using isolation sleeve or other means according to our civil engineer. We even have 3 anchor bolts next to each other on a concrete table top in the past. On steel structure support, 2 or 3 through bolting next to each other is not uncommon.
For the welding issue, I accept their ill design since no strong technical reason to reject it from everyone's opinion, but ask UT and MT on the skirt butt weld and let it go.
RE: Anchor chair gusset welded over the skirt long seam
Sounds like a reasonable response to me. Thanks for closing the loop on this discussion with your planned path forward, and also with your points about various methods of anchor bolt installation which you've seen.