welding in tight spots 1

[delagina]

I have a Channel (C15x40) back to back with 2" gap. I'm welding the channel to an end plate. Will it have problem welding the back of the channels since it only has 2" gap?

How deep will the channel be before it will be difficult for welder to weld it? I'm not familiar with how long the "weld stick" is.

 

[CANPRO]

If you weld one channel first, then it is easy to weld all around.

I'm no expert on the practical limits of welding, but I think they should be able to get 4-5" comfortably from the top and bottom.

"Welding Stick" = Electrode. I don't know exactly how long they are, I'd imagine they vary...from I've seen they're typically 12"+ long. You can google your particular electrode and see whats for sale.

If they can't weld all around on the second channel to be installed, you can prep the outside edge of the channel to get a stronger connection on the single side.

 

[hokie66]

I would not ask a welder to make a fillet weld on the second channel in that gap. Use a backing bar, and make that weld a butt weld.

 

[dhengr]

Cut and grind a 3/16 or 1/4" bevel on in inside of the webs and part way out on the toes of the channels. Fill the bevel weld from outside, then apply the 3/16" fillet all around on the outside if the channels and return it 2" down into the space btwn. the channel backs. A welder should have no trouble reaching in there that far. Whatever you are doing, there should be little potential for tension stresses across the root of the bevel welds. You could do the bevel on only one channel with a note that the other channel be fillet welded all around first. But, then you might be questioned about the fact that the welder missed the fillet weld on the back of the second channel.

 

[SAIL3]

as a rule of thumb, I use a min of 3" clearance...probably got this from someone more knowledgeable in welding than I am...

 

[connectegr]

Welding within the 2" gap is not a good idea. Achieving the proper angle of the electrode will be difficult or impossible. This will depend on the welding process. Also, proper visual inspection of the weld will be difficult. Weld the first channel with a fillet weld all-around. Weld the flanges of the second channel with fillet welds, then partial pentration weld the web of the second channel (from the outside). If required for strength the web can be complete penetration welded. But, this is more costly.

Note: with combined weld procedures, the allowable strength increase for fillet welds in tension should not be used.

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Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[CANPRO]

connectegr: whats the reason for not using the increased strength for the fillet welds?

 

[TLHS]

I'm assuming the 3/16 is a minimum size of some sort. Can you get away with just omitting the interior weld and fillet weld the one side of the channel web with something a little larger? I don't see a problem with that, given that you have the flange welds to stabilize the system.

I'm curious what you're using this for. Those are some pretty big channels.

 

[delagina]

"Achieving the proper angle of the electrode will be difficult or impossible"

@connectengr, what is the minimum angle for welding?

 

[HardyParty]

@CANEIT When using a series of welds you need to consider load deformation compatibility. Since the transversely loaded weld is not as ductile, it will tend to fracture before the longitudinally loaded weld will obtain its full strength.

AISC says: "In lieu [of considering this load deformation], it is permitted to sum the capacities of individual weld elements, neglecting the load-deformation compatibility, when no increase in strength due to the loading angle is assumed."

 

[ztengguy]

How much load do you have? why does it need to be all around?? Awful amount of welding if not needed.