Maximum weld throat at toe of channel

[PSSC]

Hello all,

I have a question about the maximum fillet weld that can be applied to the toe of a channel.
Is there guidance on what part of the channel toe should be considered the "top" of welded portion?

Thanks

 

[RPGs]

Do you have a sketch?

AISC 360-16 Specification Section J2.2b:

(b) The maximum size of fillet welds of connected parts shall be:

(1) Along edges of material less than 1/4 in. (6mm) thick; not greater than the thickness of the material.

(2) Along edges of material 1/4" (6 mm) or more in thickness; not greater than the thickness of the material minus 1/16 in. (2mm), unless the weld is especially designated on the drawings to be built out to obtain full-throat thickness. In the as-welded condition, the distance between the edge of the base metal and the toe of the weld is permitted to be less than 1/16" (2mm), provided the weld size is clearly verifiable.

 

[PSSC]

Where on the channel would you consider the "thickness"?
The code specifies to subtract 1/16" from the thickness, but where on the channel would you measure the thickness?
I would not use the flange thickness listed in SCM that dimension is almost half way up the slope.
I would think at the top of radius but I can't find anything to confirm this.

 

[dhengr]

PSSC:
You said..., “I would think at the top of radius but I can't find anything to confirm this.” And, I’m not quite sure how to interpret that. I’d say, draw a 45̊ line, from the horiz. base line, to touch the radius, wherever it does that, and that is basically the best weld throat you can get out of that condition. Having the weld be slightly convex would improve things slightly. Put a compass point at the weld root and draw a part of a circle which connects the two ends of the 45̊ line, and this shows the convex shape and a slightly larger throat. That weld is a little tougher to measure and inspect than the typical fillet btwn. two perpendicular plates. Those flg. tip radii vary a little from mill to mill for various channels, so that’s not a dimension you can pick out of a table. You should measure the channels you’ll be using.

 

[dik]

Would it not be 1/16" below the point of tangency? Not sure, but something like that?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[human909]

Throat thickness is what matters. And I would suggest that for you typical weld you would struggle geometrically getting increasing throat thickness once you weld leg length exceeds the thickness at the 45degree point on the radius.

Of course with a big enough weld with enough passes you could get an increase throat depth but you get rapidly diminishing returns once passing that 45degree point.

**That is my gut feeling. A pencil&ruler or cad sketch will give you a more clear and precise answer.

 

[1.392DL]

I agree there are diminishing returns welding above the 45 degree tangent, but you theoretically could do it with unequal leg sizes. The -1/16" max weld requirement was because the top of a plate edge would get burned off and insufficient welds appeared to be sufficient. If your weld was so critical that this level of inspection really mattered, then you would probably use a different weld or channel or surface preparation.

 

[PSSC]

When I said "top of radius" I had not laid it out. Now that I have it is obvious that would not work.
45 degrees to tangent of the radius is close to what I was envisioning.
I was hoping for some "offical" guidance but I think this is reasonable.

Thanks everybody.