Enhancement of Safety and Design in Cargo Handling Spaces to Prevent Accidental Fire or Explosion in Oil Tankers and FPSOs

Abstract

Over the last few decades, there have been a significant number of accidents on crude oil tankers, floating production storage and offloading (FPSO) and offshore units due to fire and explosion, which have resulted in loss of lives, assets, and environmental damage. These incidents increase scrutiny and questions on the current level of safety design in hydrocarbon handling spaces and other high-risk spaces in oil tankers and FPSOs. There are many factors which may contribute to these incidents, including; defects of equipment and components, overlook during design, inappropriate maintenance procedure and history, improper workmanship, and lack of company safety procedures and instruction during maintenance and emergency responses. This study is focused on and has discussed all safety aspects and barriers for the enclosed cargo-handling spaces in tankers and offshore units. Various existing regulations, standards, and guidelines have addressed safety design of enclosed cargo-handling spaces. These requirements and guidelines are referred and investigated to identify typical industry gaps in design and to recommend best engineering practices. The proposed key design recommendations may be considered at the early design stage of new building or conversion projects to enhance the overall safety and to reduce the likelihood of critical safety events. The offshore and marine industry face many inherent risks such as failure of equipment and structural integrity, collision, grounding, dropped objects, leakages, fire and explosions. Because of the constant transfer and handling of hydrocarbons in operational profile, oil tankers and floating production storage and offloading (FPSO) units have significant potential fire and explosion risks unless sound safety barriers are considered throughout all phases of the design and the construction. Often a FPSO conversion project, which uses an ageing crude oil tanker, is the preferred choice to provide a functioning FPSO facility to the offshore oil production market in timely manner. When compared with newbuilding FPSOs, a conversion project can provide shorter construction schedule and cost reduction benefits. Considerable number of FPSOs operating in the market apply a conversion-type approach, using existing oil tankers to convert to FPSOs. In a FPSO conversion project, the existing cargo pump room is used for the hydrocarbon cargo handling, transfer and offloading operations. The use of the conventional cargo pump room configuration in newly operating FPSOs has come under scrutiny compared with newbuilding projects, which typically install independent cargo pumps, such as a submergible or deepwell type, within each tank which minimizes the risk of hydrocarbon leaks to other confined spaces. The conventional pump room configuration has always presented high risks and concerns due to confined spaces, many potential leak sources, hydrocarbon handling equipment and piping, where leaks can build an explosive environment easily, and the location is situated near the safety critical areas such as accommodation, engine room, and control spaces.