6.1.2.2
The following requirements apply to vertical joints:
a. For butt-welded joints in which the thinner shell plate is
less than or equal to 10 mm (
3
/
in.) thick, one spot radiograph
shall be taken
in the first 3 m (10 ft) of completed
vertical
joint of each type and thickness welded by each
welder
or welding operator.
The
spot radiographs taken
in the
vertical
joints of the lowest
course may be used to meet the
requirements
of Note 3 in Figure 6-1 for individual
joints.
Thereafter,
without regard
to the number of welders or welding
operators, one additional spot radiograph shall be taken
in
each
additional 30 m (100 ft) (approximately) and any
remaining
major fraction of vertical
joint of the same type
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and thickness. At least 25% of the selected spots shall be at
junctions of vertical and horizontal joints, with a minimum of
two such intersections per tank. In addition to the foregoing
requirements, one random spot radiograph shall be taken in
each vertical joint in the lowest course (see the top panel of
Figure 6-1).
b. For butt-welded joints in which the thinner shell plate is
greater than 10 mm (
3
/
in.) but less than or equal to 25 mm
(1 in.) in thickness, spot radiographs shall be taken according
to item a. In addition, all junctions of vertical and horizontal
joints in plates in this thickness range shall be radiographed;
each film shall clearly show not less than 75 mm (3 in.) of
vertical weld and 50 mm (2 in.) of weld length on each side of
the vertical intersection. In the lowest course, two spot radiographs
shall be taken
in each vertical
joint: one of the
8