Shop Weld Oversized 2

[NewbieStruct]

We have two situations on project where a 3/4" plate is welded to a tube section on its face. The welds are oversized (more than our calculations). For example, at 3/8" tube wall has a 3/8" weld on its face and a 5/16" tube wall also has 3/8" weld on its face. This is against the code I believe. The code dictates the maximum weld is t-1/16". Is this oversize weld ok?

 

[NewbieStruct]

The project has already been built for about a year.

 

[hokie66]

Read the code again. The t-1/16" is when the weld is on the edge of the material, not on the face.

 

[NewbieStruct]

The plate is attached parallel to the web of the tube. Isn't this a lap joint?
Or since the "edge" is of the 3/4" material and face is of the tube wall, the edge of the 3/4" plate governs?

 

[hokie66]

Maybe I misunderstood, but a sketch would help.

 

[NewbieStruct]

Attached is the sketch. If the welds are indeed oversized what are the remedial measures?

 

[NewbieStruct]

Sorry forgot the attachment

 

[ajh1]

The limitation would be 3/4 - 1/16 = 11/16" max. The restriction is to insure that you can distinguish the edge of the weld from the edge of the plate. That said, you should be considering the strength of the tube wall where it attaches to the weld. A larger weld may not actually increase the overall capacity if the base metal of the tube becomes overstressed.

 

[NewbieStruct]

The required weld size was 3/16". The base metal tube wall does not become over-stressed with actual loads.

 

[hokie66]

ajh1 is correct. There is no code violation here.

 

[NewbieStruct]

Thanks for clearing my doubt. I am bit confused due to welds that are on the shops at another location for a similar condition. The plate this time is 1" plate. The shop drawings shows a fillet weld along the length/height of the column. The plate is wider than the column. I understand that it would be fine along the width of the column, but along the length/height of the column, should it not be a flare bevel weld?

The fabricator (might not be the inspecting/checking the actual welding) says they used fillet welds. Is that even possible? Or did they do a flare bevel weld and then tacked on a fillet weld. I am guessing in that case the fillet weld does nothing and the effective maximum thickness in design would be 5/16R

 

[gtaw]

I agree, the size of the weld is limited to lap joints and the intent is to ensure the size of the fillet weld can be measured. The 1/16 inch edge reveal provides a point of reference for the fillet weld gage. The size limitation is found in Clause 2 Design. The physical weld can be larger, if the size can be verified.

http://www.eng-tips.com/

Best regards - Al

 

[Duwe6]

"The required weld size was 3/16"." You're reading the print wrong. If the weld symbpl indicated a 3/16" fillet, the proper Code 'read' of that requirement is:
Fillet weld with a minimum size of 3/16" [allowed 1/16" undersize for no more than 10% of the length]. That 3/16" callout really means "size not less than 3/16", extra acceptable until the weld burns off the edge of the plate". The 'No Burnoff of Edges' is where the (T minus 1/16") requirement came from. Welding is NOT machining. Weld sizes are basically all "Equal to or greater than", not precise sizes.

 

[racookpe1978]

Note that US standard fillet welds are measured by leg height (assumed equal on both legs unless otherwise noted) and Euro fillet weld dwg standards specify the throat thickness (.707 the leg height).

 

[ajh1]

On your second example, you are correct, the weld should be viewed as a flare bevel due to the radius on the corner of the tube. The 5/16R value assumes that the weld is filled flat to the surface of the tube. It is permitted to use either less weld or more weld, but you will then need to calculate an effective throat distance through the weld to determine the value. The 5/16R defines the lowest point in the valley between the two surfaces that can be considered to provide fusion. The AISI Spec has an equation for determining the weld throat for any configuration of weld. The most efficient weld is actually one where the angle between the weld face and the tube is approximately equal to the angle between the weld face and the plate. This will come off looking like a flare with a fillet on top although it is possible that the flare will not completely fill the valley in that case.

 

[Duwe6]

". . . although it is possible Highly Probable that the flare will not completely fill the valley in that case."

 

[tbuelna]

Great point Duwe6. Isn't the outside corner radius of square/rectangular structural steel tubing usually something like 2X the wall thickness (or more)?