Write your message
Volume 9 - Winter and Spring 2018                   ijmt 2018, 9 - Winter and Spring 2018: 41-49 | Back to browse issues page

XML Print

Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

Eghbali B, Daghigh M, Daghigh Y, Azarsina F. Mooring Line Reliability Analysis of Single Point Mooring (SPM) System under Extreme Wave and Current Conditions. ijmt. 2018; 9 :41-49
URL: http://ijmt.ir/article-1-631-en.html
1- Department of Marine Structures, Science and Research Branch, Islamic Azad University, Tehran
Abstract:   (2662 Views)
Single Point Mooring (SPM) is a type of offshore facility that is used for the loading and unloading of oil and gas tankers in the sea. In Iran, it is briefly called “floating buoy”. The present study discussed floating type, fixed to the seabed with mooring chain. The mooring chain of SPM, which is considered one of the important parameters of its design, will be evaluated with regard to reliability in different environmental conditions. Reliability is the likelihood of a healthy and flawless functionality for a specific time according to existing and predetermined conditions. OrcaFlex Ver. 9.4e (UK) software, by Orcina Company was used for moorings analysis. For this purpose and to calculate the environmental forces in the mooring chains (in our case 6 mooring chains with a 60 degree angle), the researchers used the diffraction analysis and time history. The results revealed that; by decreasing and increasing the diameter of the mooring chain, the force applied to the mooring also decreased and increased, respectively. Also, the effects of chain diameter, direction, and amount of wave and current were studied. The behavior of wave and current showed that when the direction of the wave and the current were closer to the direction of each mooring chain, the force applied to the mooring increased. To calculate the reliability, the FORM method was employed, and to find the target point on the function, the MPP method was used. The reliability of mooring was intended to control, the value of reliability index (β), using a software program written in MATLAB, for the environment loads with a return period of 100 years. The reliability index for mooring lines of SPM was greater than 3.51, representing the safe performance of the mooring lines under environmental load.

Full-Text [PDF 1055 kb]   (1483 Downloads)    
Type of Study: Research Paper | Subject: Offshore Structure
Received: 2017/10/21 | Accepted: 2018/03/18

1. OGP (2010). Risk Assessment Data Directory – Storage Incident Frequencies.
2. Faltinsen, O. M., (1990), Sea Loads on Ships and Offshore Structures, Cambridge University Press.
3. Pecher, A. (2014). "Comparison and Sensitivity Investigations of a CALM and SALM Type Mooring System for Wave Energy Converters." Marine Science and Engineering: 2077-1312. [DOI: 10.3390/jmse2010093]
4. DNVGL-OS-E301, (2015), Position Mooring. Norway, Det Norske Veritas.
5. DNVGL-OS-E302 (2015), Offshore Mooring Chain. Norway, Det Norske Veritas.
6. Du.Xiaoping, (2005), Probabilistic Engineering Design-First Order and Second Reliability Methods, University of Missouri – Rolla. Chapter 7
7. L.MacCarthy, (2012), Probabilistic Analysis of Indeterminate Highway Bridges Considering Material Nonlinearity. Civil & Structural Engineering, Dublin Institute of Technology, Bolton St, Dublin 1, Ireland.
8. TehranBerkeley, (2012), SPM Engineering Studies for Azadegan Extra Heavy Crude Oil Export from Bahregan Oil Terminal.

Send email to the article author

Creative Commons License
International Journal of Maritime Technology is licensed under a

Creative Commons Attribution-NonCommercial 4.0 International License.