Double V-groove weld symbol

Two vees on one reference line describe one joint prepared from both sides. In cross section the result looks like an X or an hourglass, with a land in the middle where the two preparations meet. Each vee is dimensioned independently: its own included angle beyond the open end, its own depth to the left, and the root opening written once inside the joint.

The two halves are not always equal. Where access is better from one face, or where the joint has to be welded mostly in position, the designer may specify a deeper preparation on one side and a shallower one on the other. Read both sets of numbers before assuming symmetry, because welding an unbalanced double-V as though it were symmetric leaves either unfilled groove or wasted metal.

The reason to reach for a double-V on thick plate is volume and distortion. Filling a single vee through a two-inch plate takes an enormous amount of weld metal and pulls the joint angularly as it cools. Splitting the preparation across both faces roughly halves the volume and lets passes be alternated side to side so the shrinkage on one face is offset by shrinkage on the other.

The first side is normally welded, the joint turned, the root cleaned back to sound metal, and the second side filled. That sequence is not encoded in the symbol. If the drawing needs a specific order or a specific back-gouging step, look for it in the tail, in a note, or in the written procedure the tail points at.