§ 90 Positioning
- mutual movement and different movement patterns,
- the effect of current and noise from propellers,
- interference with other or joint transponders
- varying shadow effect for antennas connected to the dynamic positioning system.
ACTIVITY
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a) Manned underwater operations where loss of position entails a high risk for divers or diver platforms | 3 |
b) Other manned underwater operations where loss of position entails risk for divers or diver platforms | 2 |
c) Support vessels for manned underwater operations conducted from work boats where loss of position for the support vessel has direct consequences for the work boat | 2 |
d) Drilling and well activities where well control is ensured by a facility with dynamic positioning | 3 |
e) Facilities that produce or store hydrocarbons | 3 |
f) Flotels with gangway connected Two reference systems may be accepted for arrival and departure | 3 |
g) Vessels with offshore gangway connected to simpler facilities | 2 |
h) Activities carried out by lifting vessels or pipe-laying vessels in the vicinity of the facility (here permanently placed and mobile/floating) It may be acceptable for only two out of three reference systems to be operational upon arrival and departure | 3 |
i) Other activities within the safety zone, where the vessel represents a risk to the facility The requirement applies if the vessel exceeds the vessel size the facility is designed for with regard to withstanding a collision. Two reference systems may be accepted for arrival and departure | 2 |
j 1) Tank vessel loading from facilities handling hydrocarbons j 2) Tank vessel loading from subsea loading and off-loading installations where the tank vessel is not moored or anchored to these installations j 3) Tank vessel loading from subsea loading and off-loading installations where the tank vessel is moored or anchored to these installations | 2 2
1* or 2* |
k) Loading operations from buoys | 1 |
l) Other well activities The requirement applies to well maintenance facilities if well control is handled by another facility | 2 |
m) Shallow drilling if encountering hydrocarbons is not expected | 1 |
Notes to the table
- For dynamic positioning, consideration should be given to the reference systems' limitations as regards reliability, availability and quality.
- High risk as mentioned in this table litera a, means the cases when the diver does not have an unrestricted return to the diving bell, or where loss of the vessel's position can lead to loss of or damage to the diving bell, and possibly the associated bottom weight.
- The requirement relating to Equipment Class 3 for drilling and well activities as mentioned in this table litera d, does not apply to shallow drilling and core drilling. For shallow drilling, however, other requirements in the table may be relevant, such as the requirement relating to Equipment Class 2 for other activities within the safety zone without risk to health, environment and safety. Well activities that require Equipment Class 3, include well intervention, such as wireline operations. Other well activities as mentioned in this table litera l, with requirements for Equipment Class 2, where the production facility has well control equipment, may be well stimulations and unmanned underwater operations, including the use of remote-controlled subsea vessels or subsea tools.
- The recommendation for Equipment Class 2 for tank vessels as mentioned in this table, is conditional upon the preparation of a positioning capacity plot for the dynamic positioning system.