1. Field of the Invention
The invention relates generally to the field of connecting tubular members to each other. More specifically, the present invention relates to a system for connecting a submerged metal flowline to a flexible riser pipe that extends from the submerged flow line to a surface production or drilling facility.
2. Description of the Prior Art
It is necessary in many offshore operations to provide flow line connections between above-water facilities and submerged pipelines that may lie hundreds of feet below the water surface. Such a need arises, for example, where oil or gas from a production platform is delivered to a submerged pipeline. The riser line that extends from the platform to the pipeline is constantly moving due to platform movement, product surges, water action, and other causes. These actions cause the riser lines to deteriorate over time, requiring that they be periodically disconnected from the pipeline and replaced.
Conventional underwater connectors frequently require the assistance of divers to connect or disconnect the riser and the pipeline, which can render the replacement procedure slow and expensive. The typical nut-and-bolt-type flange connector is also relatively difficult and time-consuming to install, particularly when the installation must be performed at extreme water depths. Welding-type connections are similarly undesirable.
A variety of systems have been devised to eliminate the need for bolt-on or welded connectors in underwater pipe connection technology. In my U.S. Pat. No. 4,676,531, a system for clamping and sealing two pipe sections together is disclosed in which a hollow metal ring structure is expanded by hydraulic pressure to lock telescoped pipe sections together. While the technique described in my patent is extremely efficient and significantly improves on conventional welding or nut-and-bolt-type flange connections, it is not well suited for use in connecting pipes that must be periodically separated and reconnected.