Welding Wide Flange Splices 4

[sedonas]

When you weld two wide flange together by cutting them square... would it make sense to further strengthen the web by putting cover plates over the web? Or over the flange?The purpose of flange is for tension and compression.. the web is supposed to be only for shear? Which to focus more in welding.. But if you weld cover plates on the flange.. won't it weaken the flange by having many welded regions.. how do you weld your splices (that involves no bolted connection)?

 

[andriver]

I think you already know what our reaction to those welds are going to be. Without a grinder to grind off slag you're going to have impurities in the weld and get a weld that looks like that. On the bottom picture, the left side of the weld almost looks like a decent weld...Almost

 

[sedonas]

They used hammer and hit the weld to remove the surface black slag. So I should check each connection and make sure all slags are removed to see what's at bottom.. but for such thin sections.. there should be fusion beneath the slags.. isn't it.. by impurities you mean the slag is covering the welds or part of the mixture?

Btw.. he didn't remove the epoxy primer because they just painted it last week and would take too long to grind each (and the contractor refused such time consuming task).. and let's say the epoxy reduce the strength.. it's full weld so there should be full load bearing in between members for such small section (again 1.7mm C section on 4mm angle bar).. isn't it.

 

[moltenmetal]

Hardieboard is cement reinforced with cellulose fibres. The dust is cement dust, and the fibres themselves are nonhazardous. Yes there's a theoretical risk of harm from the dust- similar to what you'd get dry-cutting concrete. It's far better (and faster) to cut the stuff with a shear than with an angle grinder. But frankly I'm far more worried about your welders' eyes than I am about the dust exposure.

Buy the guys some old-school drop-down welding masks. The quality of their work will increase by leaps and bounds in a very short period of time- it's amazing what you can do when you can SEE WHAT YOU"RE DOING!

 

[sedonas]

You mean just wearing shades they need to close their eyes to weld.. hmm.. i'll ask them tomorrow about this and maybe give them welding goggles they can't afford.. here's what they are building:

Originally the wide flange above it will support a concrete wall above and hardieflex below.. but because of the bad splice.. we would no longer add a wall.. instead we will use the C sections and hardieflex below to support the wide flange...

Hardiflex says one middle support of it's 1.2 meter width hardieflex enough. Our designer makes it two. And instead of the original 1.4mm thick C section. We made it 1.7mm thick C section distance every 400 mm apart.. this will make them carry the w8x21 almost 21 lbs every 400mm vertical strut C section.. this will transfer the moments of the wide flange to the parapet wall below it (one meter height from slabs). This transform the frame into light gauge structure building... hopefully the safety margin and welds would make them rigid.

 

[moltenmetal]

No pair of sunglasses is as dark as a proper welding mask. The dark glass of a welding mask is not only effective at removing UV, it's also dark enough so that you can actually watch the puddle of molten metal as you're depositing it so that you can control where you're putting it, and how much the parent metal is melting etc. If you look at the arc with glasses that aren't dark enough, your vision will rapidly be impaired by flash-blindness (phosphenes- the coloured blobs of light that persist in your vision for a while after looking at a bright thing).

A VOC respirator with the cartridge you've shown is next to useless against dust. An N95 dust mask (the cloth/paper ones doctors wear) works better, is cheaper and much more comfortable. But when our staff are working with Hardieboard, we put them in HEPA respirators (same mask as your VOC cartridge, but a pink bag-type HEPA cartridge). We don't use any processes like grinding that produce respirable sized dust. In my view that's excessive for the real hazard, but if it makes people feel more comfortable and less worried, we have no problem supplying them the protective gear.

 

[Ron]

The last weld shown in the above photos has the following visually rejectable issues...just from what I can see in the photo:

1. Improper profile
2. Lap (as in cold lap or lack of fusion)
3. Undercut
4. Porosity
5. Slag inclusions

I'm sure there are others as well....

 

[TLHS]

Yeah, the standard PPE wandering around in a concrete plant here is a high quality disposable dust mask. Nothing too fancy. If it's high dust contact, full on lab style goggles are also used. Getting concrete dust in your eyes is really uncomfortable.