Max Weld size Question
Max Weld size Question
(OP)
I'm connecting a 1/8" thick tube to the bottom flange of I-beams varying in thickness from 1/4" to 7/16". Sec J2.2b of ASD states that the min weld thickness depends on the thicker of the 2 parts joined and is per table J2.4.
For the max size fillet weld it states that for material less than 1/4", the weld is not greater than the thickness of the material. Does this mean the thicker part also? or the thinner part? If it goes by the thinner part than my max weld would be 1/8", but for I-beams flanges above 1/4" thick, my min would be 3/16" (greater than the max).
For the max size fillet weld it states that for material less than 1/4", the weld is not greater than the thickness of the material. Does this mean the thicker part also? or the thinner part? If it goes by the thinner part than my max weld would be 1/8", but for I-beams flanges above 1/4" thick, my min would be 3/16" (greater than the max).






RE: Max Weld size Question
RE: Max Weld size Question
If you are lapping thin plate to a relatively thicker beam flange, the weld size doesnt exceed the thickness of the thinner part, but there has to be adequate preheat to avoid cracking. Hope this helps.
RE: Max Weld size Question
Hg
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RE: Max Weld size Question
In the first paragraph, the second sentence should read "The max size of fillet welds in J2.2b is intended for lap joints, not for a Tee connection where the plates are perpendicular to eachother".
With Tee joints, you don't have melting of the corner as when the plates are lapped.
Sorry for the confusion.
RE: Max Weld size Question
This clarifies the "that is permitted along edges of connected part" in J2.2b for the maximum size of fillet welds permitted.
RE: Max Weld size Question
1. In the 9th edition of the AISC-ASD Spec, min size(leg) of fillet weld per Table J2.4 is based on material thickness of thicker part joined.
2. The AWS reference the 9th edition of the AISC-ASD Spec for bldgs was based on is one from the 80s.
3. In the latest AISC Spec for Structural Steel Bldgs (2005), the min size of fillet weld in Table J2.4 is based on material thickness of thinner part joined
4. The corresponding Table for min fillet weld size in AWS D1.1 (96 edition onwards) is Table 5.8..variables like low hyrdogen/non-low hydrogen, preheat etc can determine whether the thicker or thinner member joined govern the min size of weld. AISC modifies this table.
Question: Even though AWS D1.1 does not stipulate a maximum requirement for fillet welds used to attach tubular members to planar surfaces in T-joint configuration, designers are expected to use their engineering judgement to limit undesirable effects of shrinkage, distortion etc.
What is an acceptable plus tolerance for specified fillet weld size in the scenario described above...or is one necessary?
RE: Max Weld size Question
RE: Max Weld size Question
RE: Max Weld size Question
RE: Max Weld size Question
For thicknesses up to and including 3/16" the maximum weld size is the thickness of the material.
For thicknesses greater than and including 1/4" the maximum weld size is the thickness of the material - 1/16".
So the maximum thickness of fillet weld for a 5/16" angle welded to a 3/16" tube is 3/16". And the maximum weld for a 3/8" tube fillet welded to a 5/16" tube is 1/4".
RE: Max Weld size Question
RE: Max Weld size Question
Maximum useful fillet weld size in a T joint is 1.414 times the thickness of the thinner part, since that gives an effective throat the same as the thinner part.
Hg
Eng-Tips policies: FAQ731-376
RE: Max Weld size Question
From what I recall, 1.414 x size(leg of convex fillet weld) = face width of inscribed triangle in fillet weld cross-section..and 1/2 of that (0.707 x size) = theoretical throat..assuming isoceles inscribed triangle.
RE: Max Weld size Question
RE: Max Weld size Question
RE: Max Weld size Question
In a lap joint, the maximum fillet weld is 1/16" less than the thickness of the plate along whose edge the plate is made, unless the plate is less than 1/4" thick, in which case the weld can be up to the thickness of the plate. The effective throat will be less than this, but that's all the weld you're allowed to put in there (and in the case of <1/4", all the weld you can get in there).
Actually I misspoke for T joints--although you're not going to get additional capacity by making your effective throat any larger than your material thickness, you may want to make that a minimum rather than a maximum, depending on your design & application, so that failure would occur in the base metal rather than the weld. Either way, the fillet weld leg size that has an effective throat equal to the base metal thickness t would be 1.414t (so that when you multiply size by 0.707 to get effective throat you're back at t).
HG
Eng-Tips policies: FAQ731-376
RE: Max Weld size Question
Using ASD '89 specs, the shear capacity of a 5/16" fillet weld is 4.64 kips per inch. If you were welding to 1/4" A36 plate, the shear capacity of the plate is 14.4(.25)=3.6 kips per inch.