Model Test And Field Survey Of A Floating Artificial Reef Moored By New Parallel Wire Cable

Abstract

Model Test And Field Survey Of A Floating Artificial Reef Moored By New Parallel Wire Cable K. Sekita; K. Sekita Nippon Steel Corp. Search for other works by this author on: This Site Google Scholar H. Okubo; H. Okubo Nippon Steel Corp. Search for other works by this author on: This Site Google Scholar H. Kimura; H. Kimura Nippon Steel Corp. Search for other works by this author on: This Site Google Scholar Y. Takahashi; Y. Takahashi Nippon Steel Corp. Search for other works by this author on: This Site Google Scholar K. Masuda K. Masuda Nippon Steel Corp. Search for other works by this author on: This Site Google Scholar Paper presented at the Offshore Technology Conference, Houston, Texas, May 1988. Paper Number: OTC-5877-MS https://doi.org/10.4043/5877-MS Published: May 02 1988 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Sekita, K., Okubo, H., Kimura, H., Takahashi, Y., and K. Masuda. "Model Test And Field Survey Of A Floating Artificial Reef Moored By New Parallel Wire Cable." Paper presented at the Offshore Technology Conference, Houston, Texas, May 1988. doi: https://doi.org/10.4043/5877-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsOffshore Technology ConferenceOTC Offshore Technology Conference Search Advanced Search ABSTRACTThis paper describes a new parallel wire cable named "New-PPWS," developed for deepwater mooring lines. New-PPWS has a slightly twisted parallel wire construction with double-layered polyethylene and laminated lead tape for water tightness. To confirm the reliability of the cable in seawater environments, we applied it, together with chains, to the single-point mooring system of a floating artificial reef in water depths of 550 meters off Kochi, in Japan. After two-year field tests the buoy was retrieved. We investigated biofoil, corrosion and abrasion of the buoy and mooring lines and carried out fatigue and breaking tests on the retrieved cables, as well as a performance test of the seawater intrusion detection system developed for the cables. Laboratory tests were also performed to analyze the dynamic characteristics of the buoy moored in waves. Based on the experimental results we evaluated maximum tension and fatigue life of the mooring system.INTRODUCTIONHigh-strength cables having good seawater corrosion resistance can be used not only for single-point mooring buoys, but also as guylines for a guyed tower and tethers for a TLP. We also have conducted research and analysis of the dynamic characteristics of these types of structures.1,2 Generally in the application of cables for the mooring of offshore structures, the following requirements must be satisfied:fatigue strength or durability that ensures the expected fatigue life of the structure.pressure tightness and corrosion resistance even in deep water (target of 900 meters).capability of being checked for soundness in service (seawater intrusion detectability).ease of handling.ease of repairing the corrosionprotective sheathing.replaceability.To meet these requirements, we developed a new cable that twists with the same pitch to allow easy reeling without snaking and that keeps all the wires straight and free of point contacts to provide excellent static strength and fatigue properties. As for fatigue strength (1), NS sockets (in Fig. 1.) are used at the cable ends, thus resulting in sockets having even longer fatigue life than the cable. The requirement (2) is fulfilled by using galvanized steel wires, sealing the cable ends with a blocking compound, double extruding high-density polyethylene as sheathing, and interposing laminated lead tape between the two polyethylene layers. The laminated lead tape offers improved seawater barrier performance and can be used as a seawater intrusion sensor if the polyethylene layer breaks. (Regarding details of New-PPWS, refer to the 1987 OTC paper, etc.3,4)New-PPWS cable, developed through the process mentioned above, was brought into production through the testing in a deepsea simulator. In order to examine its performance with respect to requirements (1) to (4), moreover, New-PPWS was utilized for the mooring cable of a fish-gathering buoy located 40 kilometers offshore of Kochi city in water 550 meters deep on December 8, 1984. Keywords: upstream oil & gas, riser corrosion, buoy, intrusion, field survey, mooring system, seawater, new parallel wire cable, cable, tosa kuroshio fish farm Subjects: Pipelines, Flowlines and Risers, Offshore Facilities and Subsea Systems, Materials and corrosion, Mooring systems, Well Integrity, Subsurface corrosion (tubing, casing, completion equipment, conductor) This content is only available via PDF. 1988. Offshore Technology Conference You can access this article if you purchase or spend a download.