Risk-Based Inspection Technique - Offshore Structures: Design, Construction and Maintenance - page 582

TABLE 8.11 Missing or Cut Members

Number of Missing Members Score

0 0

1 - 3 6

4 - 9 8

More than or equal to 10 10

No data for well-head, tender or drilling
platforms

10

Total score (limited to 10) = (tabulated score for damaged members + tabulated
score for missing members) × leg-bracing score/10

redundant load paths and are, therefore, not very damage-tolerant, while
8-legged, X-braced platforms are not as affected by missing or damaged
members.
The total weight given to damaged members is 10.5. This value was
obtained by testing the database, which showed that this level of weight was
required to increase the risk of platforms with significant damage: for example,
if the platform has four damaged members, the platform

s rank should be chan-
ged to a number that qualifies this platform to have more frequent underwater
inspections. Therefore, these scores are just a guide and definition of reasonable
scores and score weights for the fleet of platforms in the same location should
be done by trial and error.

'

Splash-Zone Corrosion and Damage
In some regions of the world, such as the Red Sea, splash-zone corrosion is a
major hazard. Survey data for splash-zone members should be collected.
Where no survey information is available, the score depends on topside
weight growth. Tables 8.12 and 8.13 are a guide for scoring this factor. The
overall weight of the total score is 10.
This factor is essential when the pile-leg annulus is not grouted and the
jacket therefore hangs from the crown weld, so that the highest utilized leg
members are in the splash zone.

Flooded Members
Flooded member detection is a common approach to inspection of offshore plat-
forms. A flooded member provides an indication of the current condition of the
member and possible existence of damage or defect, since most platform