While trying to calculate the fillet weld size required at tubular truss members, I ended up at figure 3.2, in AWS D1.1: 2000. The "t" at the top of the chart on this page appears to mean the weld size, whereas the same "t" on the details is noted as material thickness. It was always my understanding that the joint geometry, not the material thickness, determines the weld size. Because the material is extra, or double extra strong pipe in this case, my weld sizes are calculating out to be quite large. A discussion about this with the local welding inspector has him concerned about excessive heat and the resulting distortion, because of the weld size. Am I mis-interpeting the info on Figure 3.2? Is the "t" in the table intended to be the weld size and not the material thickness?