Maximum fillet weld size 3

[BAGW]

Hi,

Is there any limit on maximum fillet weld size? I am looking at some connection calculation, they have 1.5'' fillet weld. Isnt CJP easier to make rather than 1.5'' fillet weld? Is there a code limit that fillet weld cannot be greater than particular size? More than that they will have to weld all day long with so many passes to get 1.5'' fillet weld. Also, the weld end product might not be good. Has anyone come across with such thick fillet welds?

Thanks

 

[POPEYES]

I have seen no limit on maximum fillet welds in AWS references. The biggest I’ve seen in the field is 3/4” and I thought that was extreme. What would be the drawback of a bigger fillet compared to a bevel weld? Would the bevel really be faster?

 

[Celt83]

In the US the AISC specification sets some limits on the maximum size of a fillet weld. I would assume you'd want to limit the effective throat of the weld to the base material thickness, so if your getting 2" welds specified with 1" material then I'd be of the opinion that a CJP weld should be used instead.

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[Ron]

Celt is correct....reinforcement in fillet welds (meaning larger than the material thickness) is usually not considered appropriate.

Depending on the configuration and geometry, a CJP might not be practicable. Large fillets are common for column to baseplates in some applications.

One issue with large fillets is the amount of heat necessary to accomplish them. You have to be aware of crack potential upon cooling and be concerned about pre-pass and post-pass temperatures. Fillets this large are generally not pre-qualified under many codes and would need a welding procedure specification (which should be done whether pre-qualified or not).

I have seen fillets this large in quite a few applications (monorails, bridges, amusement rides, etc.) and I've also seen them crack and pull chunks out of the base metal when they attempted to do them too quickly or incorrectly. I would specify full observation of the process by a qualified inspector and do testing at appropriate points in the process (typically magnetic particle or dye penetrant for fillet welds)

 

[ajh1]

The only AISC limit on fillet welds is when they are being used in a lap joint. The restriction is to insure that edge of the plate being welded is visible so the actual weld size can be verified. Generally, fillet welds larger than the material thickness are going to generate a capacity greater than the underlying material strength. Since that would result in the underlying material failing before the weld fails it is a waste of weld metal and effort.

 

[klaus.]

in Germany we use
a < 0.7 x tmin

a is the throat of the weld
tmin is the min thickness of the 2 partners

this is a recommendation...not Code requirement

 

[canwesteng]

ajh1 is correct, there is no limit on size other than for lap joints. Hard to say without a sketch, but one thing to consider is that it's more efficient to use longer, smaller welds than shorter thicker ones.

 

[racookpe1978]

klaus. (Structural)

19 Mar 19 14:08
in Germany we use
a < 0.7 x tmin

a is the throat of the weld
tmin is the min thickness of the 2 partners

Same value. US fillet welds are designated by leg length.
For a leg = t min, (for a 45 degree fillet weld) the throat = 0.707 * tmin