Post weld to MC12x14.3 5

[McMichael05]

I am getting feedback from the EOR saying that a MC12x14.3 flange does not have enough space to fit a 1.66" OD Pipe with a 3/16 fillet weld all around. This is unusual because this is an industry standard and the fillet weld is capable of withstanding the applied loads. The EOR is asking for calculations to prove that the weld is adequate without it meeting the 7/16" shelf distance from Fig. 8-13 of AISC Manual. Does anyone have any insight on this/ can point me in the direction of a design example that proves that this connection is acceptable? [URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1624623990/tips/MC12x14.3_Post_Weld_yaxiyg.pdf[/url]
Thanks

 

[dauwerda]

Is the weld actually going to be SMAW? If it is made in the shop I would expect it to be GMAW, in which case the recommended minimum shelf distance from fig. 8-13 would not apply. Also note that it states recommended - not required. If the welder can make the weld without the larger shelf it should be a non issue.

 

[DrZoidberWoop]

The recommended shelf dimension is just that, recommended. I'd defer to the fabricator's opinion here. Oddly enough, unless the "welds required" includes the "recommended width" instead of the actual weld leg size, the markup contains contradictory language in their reference to whatever spec 055100 Section 2.5.A.1.b.

 

[271828]

This wasn't part of the question, so I apologize in advanced for offering unsolicited advice. In my experience the weld often doesn't control for an MC12x14.3 in this situation. The web bends out of plane as described in the AISC Design Guide 34 Section 7.3.3.

 

[McMichael05]

dauwerda: its going to be a field weld, not sure exactly which process. I already brought up to my client, who then relayed it to the EOR, that it is just a recommendation but they said that they want calculations to prove that it is fine without that shelf distance.
DrZoidberWoop: Thanks for pointing that out! And yeah as i said to dauwerda, i already brought up the fact that its just recommended and not required.
271828: I appreciate you bringing that up, that is something that i have accounted for in my calculations.

Im wondering if providing that the weld strength is enough and that it is not affected by any shelf distance will be enough. We will also be suggesting that stiffeners should be provided at post locations so that might make them feel better about those areas.

 

[DrZoidberWoop]

If it's going to be field welded, I'd push back hard on the EOR's opinion and recommendation of a PJP. I might even be tempted to tell them to go pound sand if they don't like it.

 

[dik]

Great reply, Doc...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

OP... there was a thread a while back about section properties of a welded ellipse. There may be information in it that you can calculate the moment resistance of the weld with the caveat that the weld method is acceptable.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[KootK]

...that it is just a recommendation but they said that they want calculations to prove that it is fine without that shelf distance.

1) There's a special place in hell for EOR's who ride delegated engineers harder than they'd ride themselves if they were doing the work. Sometimes it's just inexperience / ignorance.

2) In the interest of moving things along, just do a calc based on two arcs of weld that can be placed with the shelf. Then call the stuff without the shelf seal welds or something.

 

[dik]

Sounds like a government employee...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

Can you use D = (b-dia-1/8) / 2 as the weld size? and see what the capacity is? The calculated D will be less than the weld applied and the strength will at least be equal to the calculated D.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik