Ok. If I have two plates at 90+/- degrees. The thinest plate is .250 inch. The Standard for fillet welds say's ".9t or greater for fused leg (t=thinest member welded), .6t minimum throat.
So, I would be required to to have (2) fused legs (one leg on each plate) at .230 inch min. and a actual throat of .150 inch min. The Fused Leg(s) would measure frome the toe(s) to the intersection of the two plates. And the Throat, from the Face of the weld to the intersection of the two plates, Correct?
If this is true how deep does the penetration (into the plates) have to be, along the fused leg(s)? I understand that the penetration does not have to go beyond the root of joint, only too the root of joint, but is there something that dictates how deep the penetration has to be along the fused legs, or does it just need to be fused.
I know this may sound confusing, which I think is part of my dilema!
The penetration only has to extent to the root. How much past is not an issue as long as it makes it to the root.
You are basically correct. Theoretical throat, as was stated already, is the shortest distance from the theoretical leg intersection (root) to the hypotenuse of the triangle that represents the weld size that is desired. Actual or effective throat takes into account the amount of weld penetration achieved and is the shortest distance when measuring from the depth or penetration of the root to the actual weld face.
Now that I have added confusion to this, I suggest that you see what those differences are in AWS 3.0-2001 and in other AWS publications. The picture truly is worth a thousand words. If you can't find a copy let me know and I can email a sketch to you.
There is no requirement for minimum penetration along the fillet legs. The weld metal simply has to be thoroughly fused to the base metal along the joint.
In actual practice you will (or should) find there is some penetration past the fillet "walls" and past the root. That is, when looking at the triangular cross section, the weld will have melted outside the triangle along the 2 sides, and be just at or outside of the intersection of the 2 sides (root).
But if there were some way to control the weld so the penetration of fusion occurs only at the surface of the walls, that would be all that is needed.
Chet
There is a bit of unclear wording.
The code calls for a specific root fusion (as mentioned above)
High speed robotic lines often in the auto industry will perform random sectioning of production units and a macro etch will require a depth of penetration revealed by the etch to be 90% of the thickness of the thinner member. (beyond the root)
The two original terms appear to contridict. Fillet Weld size is further confused as mentioned in Figure 25 and Fig. 26 (C & D) of A3.0 2001.
The depth of fusion *beyond the root* measured by macro etch does indeed produce a stronger joint than one fused only to the root (leading edge of the planes). With the thin materials used in this venue I understand the reasoning. (Beveled fillets require smaller leg lengths eh?)
I feel A3.0 may be a bit unclear here.. Figure 25 (B is a good for our conversation) is titled "Weld Sizes") However only *fillet leg* sizes are determined. Fig 26 View (D) I believe shows what our conversation is all about using the term "root penetration"
Fig 24 (E) also provides a fillet weld root that both represents the two planes and the depth of penetration.
I belive the term: "The joint penetraion shall extend to the joint root". Is either redundant or non sequiter.
I'm supposed to know this stuff and am now getting a headache.
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THANK YOU! I Think everybody has helped to answer my questions. I really do appreciate everyones help. Thank you all very much!