Understanding API ICP653 Reading 7-Worksheet-04 Part1

4.3.1.3 Shell corrosion occurs in many forms and varying degrees of severity
resulting in a generally uniform loss of metal over a large surface area or in
localized areas. Pitting may also occur, but does not normally represent a
significant threat to overall structural integrity unless present in a severe form
with pits in close proximity to one another.
4.3.1.4 Methods for determining the minimum shell "t" suitable for continued
operation are given in 4.3.2, 4.3.3, and 4.3.4. (see page 1-11 below for
minimum shell “t” formula.)
4.3.1.5 If the "t" requirements cannot be satisfied, the corroded or
damaged areas shall be:
a. Repaired, or
b. Allowable liquid level reduced, or
c. Tank retired.
NOTE: The maximum design liquid level shall not be exceeded.
Charlie Chong/ Fion Zhang