Construction of large scale structures such as buildings, containment vessels or pipes, can be constructed off site but sometimes are constructed on site. Construction of the structure is typically done where the materials are readily available and can be assembled on site. However, some structures require use of composite materials which are not amenable to on-site construction. Composite materials provide excellent structural properties and compression characteristics as compared to normal construction materials made of wood, brick, steel or cement. Composite materials are also known to have improved strength properties and are lighter in weight than typical construction materials.
An exemplary large structure is proposed for use as a cold water pipe that is part of an ocean thermal energy conversion system. Briefly, such an energy conversion system utilizes the difference between warm surface water and deep cold water to drive a “steam cycle” that turns a turbine and generates electrical power. In order to implement such a system, a large scale pipe must be constructed. These pipes can have diameters of several meters and can be hundreds and even thousands of meters in length. An ideal pipe is believed to be ten meters in outer diameter and one thousand meters in length.
It has been proposed to construct such structures with composite material sandwich panels and various methods have been developed. These methods include manufacture by hand, resin transfer molding, compression molding and/or filament winding. One promising approach is to utilize a vacuum assisted resin transfer molding process wherein a plurality of fabric rollers are disposed in a cylindrical arrangement. Selected lengths of fabric are then pulled down into a molding machine and the resin is impregnated into the fabric rollers in a manner well known in the art. After this portion of the molding is completed, the section is lowered into the water and a next section is molded. This process is repeated until the structure is complete. Another process is to simply construct pre-formed panels in a cylindrical arrangement and secure these panels to one another by hand. This structure is then lowered and joined to another section and the process is completed until the structure is complete.
Although the aforementioned processes are believed suitable for constructing a large scare structure, it is believed that they have a number of shortcomings. Specifically, these aforementioned processes are time consuming and require installation of expensive onsite resin transfer manufacturing equipment for each large scale construction. Therefore, there is a need in the art for a relatively inexpensive, yet reliable method of constructing a large scale structure. There is also a need to utilize component parts that can be easily shipped to the site and then rapidly assembled. There is also a need for a composite structure with interlocking seam joints and butt joints secured to one another under compression with reinforcing materials so as to provide adequate strength for the completed structure.