Preloading to reduce loads and save steel on topsides and grillage of catamaran systems

Abstract

The present invention reduces loads and saves steel on topsides and grillage of a catamaran system by creating a counteracting moment to offset a sagging bending moment of its self-weight on the topsides during transportation. The present invention can reduce the span of the supports on the topsides on the catamaran float-over barges and move the reaction forces toward inner edges of the float-over barges. The counteracting moment can cause a reduction of stress on the topsides' and grillage's members caused during the topside offloading and transportation. The stress reduction can result in the members withstanding the additional dynamic load caused by a catamaran system without increasing member sizes adequate for an offloading operation. The reduction results in a significant savings, given the size of a typical topsides for a Spar hull.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Not applicable.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]Not applicable.REFERENCE TO APPENDIX[0003]Not applicable.BACKGROUND OF THE INVENTION[0004]1. Field of the Invention[0005]The invention disclosed and taught herein relate generally to Spar topsides installation methods and systems; and more specifically related installation methods and systems to preloading float-over barges to reduce loads and save steel on topsides and grillage of catamaran systems.[0006]2. Description of the Related Art[0007]A Spar platform is a type of floating oil platform typically used in very deep waters and is among the largest offshore platforms in use. A Spar platform includes a large cylinder or hull supporting a typical rig topsides. The cylinder however does not extend all the way to the seafloor, but instead is moored by a number of mooring lines. Typically, about 90% of the Spar is underwater. The large cylinder serves to st...

AI Technical Summary

Benefits of technology

The present invention is about a method and system for reducing loads and saving steel on the topsides and grillage of a catamaran system during transportation. It achieves this by creating a counteracting moment to offset a sagging bending moment of its self-weight on the topsides. This reduces the size of the supports on the topsides and moves the reaction forces toward inner edges of the float-over barges, which can lead to a significant savings in material and labor. The method involves transferring the topsides onto at least two float-over barges, installing sea fastening members, and adding ballast to the barges to at least partially counteract the wave load created on the catamaran system. The preloaded catamaran system with the topsides and float-over barges can then be transported to a location for installing the topsides on the Spar hull.

Problems solved by technology

The stress reduction can result in the members withstanding the additional dynamic load caused by a catamaran system without increasing member sizes adequate for an offloading operation.

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