Publications

During the investigation of a recent process tank fire, it was determined that hydrocarbon gas was released through the malfunctioning and poor integrity of the tank liquid overflow handling system. This allowed gas to freely flow through the water seal system and into the below grade open drain. Several corrective actions were put in place and a significantly improved overall water seal design was successfully developed and safely executed in the field to address all critical tanks exhibiting constant and/or intermittent gas release. This improved design, which uses the existing water seal system, consists of a new upright elbow/horizontal P-trap spool with its highest point above the water seal system to keep the water level at that elevation and provide a complete sealing. A second design concept was also proposed and executed for these liquid overflow handling systems where the water seals have integrity issues due to their design. This design replaces the entire liquid overflow handling system from the tank overflownozzle all the way to below grade open drain and it is fully inspectable by conventional methods. The design uses a double elbow/horizontal P-trap upsidedown spool to hold the water for sufficient head to seal the gas from exiting the tank while allowing liquid overflow discharging into the open drain. This paper aims to provide a detail sequence of technical development, lessons learned and design concepts and intends to provide doable ecommendations for swift corrective actions of existing aboveground process and storage tank overflow handling systems in oil and gas industry while proposing a new design for inclusion into the applicable codes and standards.