Risk-Based Inspection Technique - Offshore Structures: Design, Construction and Maintenance - page 577

TABLE 8.6 Pile Strength Factor

Answers to Input
Questions

Score
<

Score
≥

Criteria 1975 1975

Existing pile penetration achieves target Y, Y, Y 2 0

Existing pile penetration known but not
target

N, Y, (N/A) 3 2

Target pile penetration known but not
existing pile penetration

Y, N, (N/A) 7 3

Existing pile penetration does not meet
target

Y, Y, N 8 7

Target and existing pile penetration
unknown

N, N, (N/A) 10 10

Disturbance from Jack-up Feet Factor

No seabed disturbance 1

Depression > 0.3 m < 5 m from pile 1.4

No data 1.4

Score = Score from table × factor (max score equals 14)

Risers and Conductors
Previous factors have been associated directly with the strength and redun-
dancy of the platform and how the particular issue affects the platform sabil-

ity to withstand extreme events, such as waves and earthquakes. However,
appurtenances like risers and conductors also contribute to the platform

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likelihood of failure and need to be included in the quantitative risk calcula-
tion, since inspection of these items is also typically included in an under-
water inspection.
Caissons for fire-control water and other important activities are considered
a riser. Note that appurtenances like boat landings, walkways and barge bum-
pers have been excluded since they generally play a much smaller role in plat-
form risk than risers and conductors do.
Risers and conductors that contain hydrocarbon gas or oil can result in an
explosion or fire that can damage the platform or cause it to fail. The score
increases with the number of risers or conductors, since there is an increased
likelihood of damage as the number of them increases.

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