Is there a limitation on maximum size of fillet weld? 1

[tapu]

Looking at AWSD1.1 table 5.8 Note B states ...except that the weld size need not exceed the thickness of the thinner part joined.
That statement does not say shall not exceed as it does for groove weld. Please advise.

 

[kingnero]

I don't know any USA codes, but I've always used the "thickness of the thinnest part" advisory.

No need to make a stronger weld than the surrounding structure can handle.

 

[metengr]

Agree with the above advice. In fact, an oversized fillet weld can result in reduced fatigue performance in service.

 

[Duwe6]

Neither AWS nor ASME limit the size of a fillet weld. They both presume that the Engineer-of-Record will use good judgment in deciding when to switch from a fillet-only joint to a Partial-Penetration with fillet reinforcement joint. Huge fillets on both sides of a plate have a tendancy to delaminate that plate during weld shrinkage. Additionally, huge fillets take longer to weld than making a Parital-Penetration or Full-Penn joint [even figuring in the prep time for the groove preparations].

In the as-welded condition, it is the responsibility of the AWS Welding Inspector [to comply with D1.1, an Inspector and full inspection are mandatory] to determine if excess weld metal is detrimental. If the Inspector is not sure if a particular instance is detrimental, he/she is to ask the Engineer-of-Record.

 

[desertfox]

Hi tapu

Try looking on page 5 of this link it refs AISC

http://faculty.delhi.edu/hultendc/AECT250-Lecture 14.pdf

 

[tapu]

Thank you all, I agree with your recommendations and as general practice is it norm to have a fillet weld size to be no larger then thinner part of connected material. But the fabricator isn't agreeing with the judgment call.

 

[Duwe6]

You might want to remind your fabricator that if he wants to engineer or reengineer your weld details, he has to sign the drawings and assume some of the liability.

He'll stop talking then.

 

[MintJulep]

It's rare that a fabricator would want to make a fillet bigger as it generally takes more time to do so, and cuts into his profit.

So if your fabricator is telling you that he wants to make a bigger weld you should discuss the situation with him.

He might know something, even if he can't articulate it.

 

[tapu]

Yep, we just spoke and apparently he had welded the components without noticing the comments that were sent back and now he is trying to get the approval of what is done.

 

[MintJulep]

Or that...

 

[connectegr]

Using an "oversized" fillet weld should not be detrimental in most structural steel applications. If undercutting occur or other weld discontinuities, these are another issue. But fabricators frequently use 1/4 or 5/16 single pass fillet welds in place of small welds required for strength. If multi-pass welds were substituted for smaller requirements, this is very inefficient, but may not be a design problem.

The reference noted by desertfox, for maximum fillet sizes, is for lap joints. For material 1/4" or less the leg size can equal the full thickness of the lapped edge. For larger thicknesses a 1/16 edge should remain. In these cases, I have seen welds built-up and transitioned. But, this also would be inefficient for most structural conditions, as the base metal would not match the weld strength.

http://www.FerrellEngineering.com

 

[racookpe1978]

So if your fabricator is telling you that he wants to make a bigger weld you should discuss the situation with him.

He might know something, even if he can't articulate it.

Or he has created a massive fillet weld to overcome a large "hole" or gap between the two parts that should have been properly fitted together with no gap at all ..... But I'm "jest" a little bit cynical. 8<)

 

[MintJulep]

Ok, ok....

If your fabricator is telling you before he starts welding that he wants to....

 

[DWHA]

I was always told that weld details shown on our plans were minimum weld requirements, unless noted different. Therefore, the fabricator has met the requirements.

OR

You could argue and say, that he is not within acceptable tolerances. And because of that, he either needs to replace the out of tolerance parts or hire a licnesed engineer to review the situation and assume responsibility for the part in question.

 

[USAeng]

would aws d1.1 section 2.4.5 apply? I have 1998 copy so number might have changed but it is for "Maximum Fillet Weld Size"

thickness of base metal for metal less than 1/4" thick

and 1/16 less than thickness of base metal for metal > 1/4" thick unless it is designated on dwg to be built out to obtain full throat thickness

 

[dik]

For HSS tubes CIDET recommends using a max weld size less than 1.1 times the welded part... this, from research, provides nealy the full strength of the section nearly a CJP without the backer bar.

I usually design HSS sections for about 70% to 80% of the capacity just to avoid using a CJP weld...

Dik

 

[gtaw]

D1.1 does not address the maximum size of a fillet weld except in the case of a lap joint. If the joint in question is a lap joint, the weld needs not be larger than the thickness of the member if it is less than 1/4 inch or 1/16 inch less than the thickness of the base metal if the thickness is 1/4 inch or thicker. Refer to figure 2.1 in D1.1-2010 (as an example). However, that limitation is for the design of the weld, not the inspection or acceptance of the weld. You may find Figure 5.4 and Tables 5.9 and 5.10 helpful (also found in AWS D1.1-2010) useful.


There is no basis for rejecting an oversized fillet weld in any of the AWS D1.x structural welding codes.

Should a third party inspector ask that an oversized fillet weld be reduced by grinding or otherwise, I would comply, but I would bill his employer for the cost of handling, reworking the welds, and repainting plus any additions costs incurred for unnecessary rework or repairs. I've done it before and it can be very profitable.

Make sure you are not reading into the code requirements something that is not there. It can cost the inspector his job when the employer or owner receives a sizable bill for unnecessary rework.

I am not an advocate of making larger than necessary fillet welds, but I caution inspectors not to apply requirements that cannot be substantiated by a code or contract requirement. A recommendation is not the same as a requirement.


Best regards - Al