in turn, should be joined to the main pillars, as shown in Figure 17.5. The key ingredient
that makes these schemes work is that, for a land-based installation, it is more
important that the grounding system extends under the entire structure than that the
ground is low resistance. This is similar to the CBN used in several-storey structural
steel buildings.
Section I-701 of the standard DNV-OS-D201 [23] specifies that ‘Aluminium superstructures
that are provided with insulating material between aluminium and steel
in order to prevent galvanic action are to be earthed to the hull . . . with wires or
bands . . . with a maximum connection distance of 10 m.’ This is important because
many problems encountered in grounding systems of OOIs are related to corrosion
generated by galvanic action from the use of dissimilar metals. The distance
should be reduced to below 10 m when radio interference is concerned. Standard
E-CR-001 [21] refers to local recommendations for the grounding system.
Connections between CBN, grounding lead conductors and the main pillars of the
OOI should be exothermic or of an irreversible compression type, able to meet the
specific requirements of the task for which they are being installed, with corrosionresistant
layers or films at the point of connection.