A Comparison of the Dynamic Response of a Product Transfer System in CALM and SALM Oil Terminals in Operational and Non-Operational Modes in the Persian Gulf region


1 Offshore Structure Engineering Department, Petroleum University of Technology, Abadan

2 Mechanical Engineering Department, Petroleum University of Technology, Abadan


Offshore oil terminals are a cheaper and safer solution than conventional shore terminals for unloading and loading tankers. There are several types of offshore terminals, including Catenary Anchor Leg Mooring (CALM) and Single Anchor Leg Mooring (SALM). Product transfer systems, including floating and underwater pipes, are the most important components of these terminals. The present study aims to compare the dynamic response of a product transfer system in these two models of offshore oil terminals. To obtain structural responses, including forces created in floating and underwater pipes, a simulation in Orcaflex software is used considering wind, current, and wave forces in different sea states. The curvature and tension in the pipes are considered a criterion for evaluating the failure modes. The results show that under operating conditions, the curvature and effective tension of the pipes in the SALM terminal are 5% and 93% lower than those in similar operating and environmental conditions in the CALM terminal, respectively. As the environmental conditions increase up to Sea State 8, when the tanker is not connected to the terminal, the SALM terminal pipes will have more structural stability and usability, while the CALM terminal pipes will only have stability up to Sea State 6. The tensions generated in the pipeline end manifold (PLEM) of the SALM terminal are also lower than those in the CALM terminal. It is also observed that the critical point for the CALM terminal pipes is the connection point to the terminal buoy, while it is the connection point to the seabed for SALM terminal pipes, which should be considered in designing a product transfer system for this type of terminals.


  1. J. F. Wilson, "Offshore structures (marine engineering)," 2003. [DOI:10.1016/B0-12-227410-5/00512-3]
  2. J. J. Ziccardi, "Selection of hose systems for SPM tanker terminals," in Proceedings of the Annual Offshore Technology Conference, 1970, vol. 1970-April. [DOI:10.4043/1152-MS]
  3. I. Brady, S. Williams, and P. Golby, "A study of the forces acting on hoses at a monobuoy due to environmental conditions," in Proceedings of the Annual Offshore Technology Conference, 1974, vol. 1974-May, pp. 1051-1057. [DOI:10.4043/2136-MS]
  4. C. Eiken, "Pre-commissioning hose operations on the Valemon field in the North sea." University of Stavanger, Norway, 2013.
  5. X. Qi, Y. Chen, Q. Yuan, G. Xu, and K. Huang, "Calm buoy and fluid transfer system study," in Proceedings of the International Offshore and Polar Engineering Conference, 2017, pp. 932-939.
  6. C. V. Amaechi, F. Wang, X. Hou, and J. Ye, "Strength of submarine hoses in Chinese-lantern configuration from hydrodynamic loads on CALM buoy," Ocean Eng., vol. 171, pp. 429-442, 2019. [DOI:10.1016/j.oceaneng.2018.11.010]
  7. A. R. C. Girón, F. N. Corrêa, A. O. V. Hernández, and B. P. Jacob, "An integrated methodology for the design of mooring systems and risers," Mar. Struct., vol. 39, pp. 395-423, 2014. [DOI:10.1016/j.marstruc.2014.10.005]
  8. A. R. Cruces Girón, F. N. Corrêa, B. P. Jacob, and S. F. Senra, "An Integrated Methodology for the Design of Mooring Systems and Risers of Floating Production Platforms," in International Conference on Offshore Mechanics and Arctic Engineering, 2012, vol. 44885, pp. 539-549. [DOI:10.1115/OMAE2012-83702]
  9. A. R. C. Girón, F. N. Corrêa, and B. P. Jacob, "Evaluation of safe and failure zones of risers and mooring lines of floating production systems," in Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, 2013, vol. 1, p. V001T01A024.
  10. S. Karegar, "Flexible riser global analysis for very shallow water," Faculty of Science and Technology, vol. Master. University of Stavanger, Norway, p. 101, 2013.
  11. A. Pecher, A. Foglia, and J. P. Kofoed, "Comparison and sensitivity investigations of a CALM and SALM Type mooring system for wave energy converters," J. Mar. Sci. Eng., vol. 2, no. 1, pp. 93-122, Feb. 2014. [DOI:10.3390/jmse2010093]
  12. Orcaflex, OrcaFlex Manual version 9.7a,2015. section 1;3;4;6;7, 2015.
  13. DNV-RP-C205, "ENVIRONMENTAL CONDITIONS AND ENVIRONMENTAL LOADS," in The Sixteenth International Offshore and Polar Engineering Conference.
  14. A. Ozorishin, "FSO concept for shallow waters in the Vietnam offshore oilfield-block Hanoi trough-02." University of Stavanger, Norway, 2012.
  15. D. N. V. O. DNV, "DNV-OS-E301 ((POSITION MOORING))." Det Norske Veritas Offshore Standard, 2010.
  16. OCIMF, "Prediction of wind and current loads on VLCC's," in Published by Oilcompanies International Marine Forum, London, England, Printed by Witherby & Co Ltd., London, England, 1977.
  17. R. P. Api, "17B Recommended Practice for Flexible Pipe," Am. Pet. Institute, Washington, DC, 2008.