Understanding API ICP653 Reading 7-Worksheet-04 Part1

9.10 Repair of Tank Bottoms (Definition see paragraph 3.9)
9.10.1.1 See figure 9-5 for details for welded-on patch plates
9.10.1.2.1 No welding or weld overlays are permitted within the critical zone,
except for welding of:
a. Widely scattered pits.
b. Pinholes
c. Cracks in the bottom plates.
d. Shell-to-bottom weld.
e. Welded-on patch plates
d. Replacement of bottom or annular plate.
9.10.1.2.4 If more extensive repairs are required within the critical zone (than
as listed in 9.10.1.2.), the bottom plate (under the shell) shall be cut out and a
new plate installed.
9.10.1.2.5 This is a new paragraph that gives the requirements for
reinforcement plates.
REVIEW NOTE: Weld Spacing requirements must meet API-650 (3.1.5.4 and
3.1.5.5) requirements. No 3 plate laps closer than twelve inches (12") from
each other, from the tank shell, from butt weld annular joints and from joints of
the annular ring to normal bottom plates.
Charlie Chong/ Fion Zhang