Explosion prevention system for internal turret mooring system

Abstract

A method and apparatus for ensuring against explosion of the gaseous atmosphere of a closed chamber, such as the QDCD room of an internal turret of an offshore production and offloading buoy wherein the closed chamber has production risers and conduit connectors that represent a potential source of flammable gas. The method comprises mixing and diluting the oxidant content of the air by introducing within the closed chamber a sufficient quantity of inert gas to render the mixture of the air and any flammable gas non-combustible regardless of the flammable gas content of the mixture. The method includes removal of the non-combustible mixture of air and any flammable gas from the closed chamber by purging thereof to the natural atmosphere, while introducing inert gas, thereby leaving a substantially inert atmosphere within the closed chamber. The turret system provides for control of the gaseous atmosphere within the closed chamber at all modes of turret operation, including the idle, on-line and ventilation modes and also provides for gas pressure control to accommodate normal operating conditions and conditions of gas leakage into the chamber.