Mechanical support of the installation trunk
Due to its physical size and weight, and the fact that the installation trunk penetrates the vessel hull, it is very important that both the hull unit and the installation trunk are installed and secured properly.
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A Strengthening knee plates (stiffereners)
B Installation trunk
Important
The installation trunk must be secured to the bulkheads and/or the hull by means of strengthening plates (stiffereners). The dimensions and strength of the plates must be adequate to prevent any vibrations. This is an invariable requirement to ensure the safety of the SU90 system and the vessel.
The shape and locations of the strengthening plates must be determined by the installation shipyard based on the physical properties of the installation trunk, the hull and the space available. Minimum four strengthening plates must be used. Each strengthening plate must extend all the way from the bottom to the top of the installation trunk. Only leave a small gap to allow access to the bolts and nuts used to secure the mounting flange. The minimum plate thickness is 10 mm, but the classification society can specify other dimensions.
The forces to which the hull unit and installation trunk are exposed depends on the physical size of the units, where they are located, and the vessel's behaviour in rough sea. It is very important that the hull unit and installation trunk are sufficiently supported. The forces applied by vibrations and the vessel's movements in the sea can affect the quality of the system performance, the endurance of the physical installation, and the vessel's safety.
The strengthening plates must be designed and manufactured by the installation shipyard to fit the installation trunk. All calculations made to support the design must meet the applicable safety requirements, and apply to the physical properties of the complete installation. It is the installation shipyard's responsibility that the installation trunk and the hull unit gantry are properly secured against vibrations and sudden movements caused by the vessel's behaviour in the sea.
Note
The design and mounting of the installation trunk for the SU90 system must be approved by the vessel’s national registry and corresponding maritime authority and/or classification society. Without a proper mechanical support for the installation trunk, the guarantee will be void!