Understanding API ICP653 Reading 15-Worksheet-11a

QW-405.3 A change from upward to downward, or
from downward to upward, in the progression specified
for any pass of a vertical weld, except that the cover or
wash pass may be up or down. The root pass may also be
run either up or down when the root pass is removed
to sound weld metal in the preparation for welding the
second side.
Charlie Chong/ Fion Zhang