This appears to be a design that was originally not a weldment. I have seen changes in design (to weldments) proposed. It is suggested (above) that the pad is an addition. Two things can be awkward in this: 1) the shape of the equilizer suggests that it could be flame-cut from rolled plate; and 2) the pad appears to be attached with a fillet weld (a common cost-saving arrangement).
A fillet weld ends at the two fit-up surfaces of the joint, making these two surfaces form a ready-made crack ending at the unseen inner surface of the weld bead. This crack will propagate into and through the weld material, depending on loading-- impact loading being a problem.
Flame-cut edges may also have cracks which can propagate into welds; it is unclear exactly what the welding detail may have been on the lower surface of the hanger in the pad area, which is a tension area.
--Frank
