Reliability Analysis of Single Point Mooring (SPM) System under Different Environmental Conditions

Abstract

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 1 method was employed, and to find the target point on the function, the MPP 2 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.

Reliability Analysis on the Effect of Subsea Buoy to the Tension of Spread Mooring System

“…Because the mooring lines in the mooring system will receive a combination of tensile, bending and fatigue loads [12]. In addition, due to the high operating costs of offshore facilities and their highly sensitive operation, assessing the reliability and risks of their design and operation, and especially the operation of mooring lines, becomes very important [7]. From research of the reliability of the FSO mooring line using the MVFOSM method explains that the reliability of the mooring line is influenced by pretension on the mooring line, MBL, and the environmental conditions the FSO is in as well as the load of the FSO [13].…”

“…2023. 802-809 (pISSN: 2541-5972, eISSN: 2548-1479 803 Furthermore, an analysis of the reliability of the mooring system on the SPM under extreme wave and current conditions has also been carried out, reliability analysis was carried out using the FORM method and this analysis shows that increasing or reducing the diameter of the mooring line will also affect the forces that occur on the mooring line [7]. Reliability analysis on SPM was also carried out using the MVFOSM method.…”

Scientometric Review and Thematic Areas for the Research Trends on Marine Hoses

“…The literature search found some models conducted on the CALM terminals with marine hoses and floating buoys to understand the motion response using coupled models, computational fluid dynamics (CFD) models, hydrodynamic models, and experimental models [95][96][97][98][99]. However, important aspects of SPMs are their integrity management, life extension and reliability [100][101][102][103][104][105][106][107][108][109][110], mooring response, fluid-transfer mechanisms, and the response of the marine hoses at SPM terminals [100][101][102][103][104][105][106][107][108][109][110]. Another challenging area of marine engineering is failure modes of marine hoses and the installation of conduits such as pipelines, submarine hoses, umbilicals, and subsea marine risers [111][112][113][114][115][116][117][118][119][120][121].…”