Abstract
Saudi Aramco has been a major player in the LPG (Propane and Butane) market since the 1960s and the company continues to be the source of benchmark pricing in the industry. A variety of refrigerated storage tank concepts have been developed to support international export of LPG products. Currently the industry has shifted to the use of safer full containment tank systems which have the capability to contain liquid and vapor release. Economic implementation of new tank systems has the potential of improving safety at company facilities. The benefit of the full containment storage tank is attractive given that the industry is focused on safety and environmental protection. However, the implementation of this technology is challenging due to the cost. Establishing selection criteria is important for economic implementation of any tank type. The paper explores the key design aspects of each type of tank arrangement based on risk assessment, project requirements and economic factors. The paper provides a case study of a current Saudi Aramco project being planned for new installation of LPG storage tanks at a size of one million barrels for both propane and butane services. The risk assessment examined the compliance, business interruption, environmental impact and other factors related to tank containment failures. The risk assessment and technoeconomic study demonstrates that the double steel full containment design is preferred over the prestressed concrete outer container with steel inner container. The double wall steel full containment tank system has been successfully deployed in facilities at sites around the world including at Marcus Hook, PA in the United Sates and Salalah in Oman. Single containment storage tank is not recommended for large scale of LPG storage or when tank is situated with other nearby facilities. Moreover, single containment type requires more plot area due to external diking requirements compared with double wall and full containment storage designs. Optimization of tank type selection may result in reduction of 6 to 8 months in project schedule and savings to the project of up to 70% of the storage tank installation cost. A risk assessment on different storage tanks designs reveals that the double steel wall full containment design is optimal from a cost and schedule prospective.
