Using less than minimum prescribed fillet weld size 1

[weab]

I know what the code says for minimum weld size. It indicates minimum fillet legs to assure quality welds and “ductility”. (I'll admit that I can't see the need for ductility in weld material, but that's what my references and AISC indicate is required of a weld.) Is there any other way to mitigate a situation when you can only use a smaller leg?

I have a situation in which my client already used a weld that is strong enough but doesn't meet the minimum requirements. A flange splice plate (5/8" thick) was placed below a beam flange and almost as wide as the flange. The AISC minimum prescribed weld size is 1/4" equal leg fillet, but a 3/16” weld would be sufficient for strength. There is only 3/16" (4.5 mm) available on each side of the splice plate for a weld. However, visually the weld is 3/16" on one leg along the bottom flange and at least 3/8" (10 mm) on the other leg going along the edge of the splice plate thickness, that is, the weld is not an equal leg weld. Doing the math, the cross sectional area of the weld is more than the area of a standard 1/4" fillet weld. This might mean that more welding heat was applied so that the heat sink effect on the weld has been mitigated. Is this satisfactory?

What if I had the client x-ray the welds for cracks? If OK, can the welds be assumed to be OK? Is ductility assured?

I am not afraid to tell the client to replace the plate if it is necessary. That would certainly be the easy way out but not serving the client well if I can prove the weld quality in other ways. I know that the code does not address every possible situation. So…does anyone have any words of wisdom on this? If so, do you know of a reference that can back up your reasoning.

Thanks for the help.

 

[SectionIX]

Weab,

With all due respect, if you don't understand the need for ductility in weld material, you need to read up on this subject. Having said that:

You can't effectively radiograph fillet welds. Even if you could, the absence of cracks does not correlate to any mechanical property. Neither does MPI, LPI or VT.

Does the drawing allow an unequal length fillet? How do you know that a 3/16" weld will be acceptable for strength? Are you willing to sign off on this and accept (potentially) the legal responsibility if the weld fails? The clients Design Engineer needs to be addressing this matter. If they approve it, they need to sign off on the reports and accept welds that do not meet Code and/or their own internal specifications. If you knowingly accept a weld that you know doesn't meet code, you place yourself in a bad situation.

Finally. you should always endeavor to do the right thing for yourself, the client and the safety of the public. Taking the easy way out is a recipe for disaster. Not looking to beat you to death, but I've seen this end badly (really badly) for other inspectors in your situation...

 

[bb29510]

the strength of the weld is in the leg size not the cross section, by reducing the size from requirement you are also lowering the safety factor of the engineering calculations. If it calls for a 1/4 welds, then a 1/4 it should be.

master ICC inspector, AWS CWI