The difference between the two welds, plug and slot, is in the shape of the hole in which the weld metal is deposited to fuse the two members of the joint. The plug weld is made through a round hole, and the slot weld is made through an elongated hole, Figure 15.1. Note that a plug weld symbol (not a slot weld symbol) is used to designate a fillet weld in a round or slotted hole.

Plug welds and slot welds are identified by the same symbol, a diameter symbol placed on its left side 0

, Figure 15.2(a). They may also be distinguished from one another in that a slot weld is identified by reference to a detail drawing in the tail of the welding symbol. The detail drawing shows the shape, location, and orientation of the slot weld, Figure 15.2(b).

When the weld symbol for plug or slot welds is located below the reference line, the hole is in the arrow side member of the joint. When the symbol is located above the reference line, the hole is in the other side member, Figure 15.2(a) and (b). The symbol for plug or slot welds is not used to have a both sides significance.

Reference in the tail of the welding symbol may be made to specify other sources of information for prepara­tion and completion of a slot or plug weld, Figure 15.3.

FIGURE 15.2(a) ■ Arrow side plug weld.