The length of the slot weld can be obtained from the ratio of

The length of the slot weld can be obtained from the ratio of plug or slot weld For example, a square groove weld has a square cross section, a spot weld is the shape of a spot, and the cross section of a slot weld is the shape of a slot plug and slot weld Slot and Plug Symbol Slot and plug welds are made when holes are created in one material and then welded to another by filling the holes with weld metal

plug and slot weld My logic is that it isn't a fillet weld that is limited to the inside corners of the slot, , the fillet weld is deposited on the joint,

plug weld and slot weld A plug weld joins the surface of a piece of material to another piece through a hole The hole can be partially or completely filled with the weld material  Plug Weld or slot weld: It is used for attaching flat plates using one or more holes or slots in the top part and then filling with filler metal to fuse the two