著者

山川 賢次 守谷 敏之 村上 卓也 早崎 清志 鯖江 敏彦 岡畑 成樹 井上 新也 神戸 良三

出版者

海上技術安全研究所

雑誌

海上技術安全研究所報告 (ISSN:13465066)

巻号頁・発行日

vol.3, no.3, pp.287-367, 2003

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A wire rope used in a marine environment has a great degradation due to corrosion. An accurate inspection is necessary to ensure the safety of wire ropes. However, technical background data of wire rope is quite few at present, and is not sufficient for wire rope inspection. Gathering the technical data is important to establish and ensure the offshore structure's maintenance technology including wire rope inspection. A laboratory test of wire rope degradation was carried out with seawater tanks for 5 years from 1994 to 1999. 14 types of ropes were used for the experiment. Further, an exposure test in real sea area was also carried out for 11 months in 1997 to acquire degradation data in dry zone above sea level, in ebb zone, and in the seawater zone. 8 types of ropes and 3 types of wires were used for the exposure test. During the test period, we examined the ropes for several times on the following characteristics, (1)appearance of ropes and strands, (2)cross section of each wire layers, (3)mechanical properties of ropes- rope diameter, breaking strength, elongation, (4)mechanical properties of wire: diameter, tensile strength, number of torsion (5)mass of coating. The changes of characteristic values are curve fitted with a line to eliminate fluctuation errors. We calculated most suitable characteristics values when the experiment is over and converted into normalized values divided by the initial values. Degradation of several kinds of wire rope was investigated with normalized characteristics values and observation results of wire rope and cross section.

著者

遠藤 久芳 菅 信 大松 重雄 山川 賢次 菅 進 渡辺 健次

出版者

運輸省船舶技術研究所

雑誌

船舶技術研究所報告 (ISSN:0495775X)

巻号頁・発行日

vol.19, no.4, pp.257-283, 1982

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The study had been started from the review^<19)> of "Plan of Ocean Raft System for Hydrogen Economy"^<1)> which was proposed by Ohta^<1)> and Veziroglu in 1977. The project was for hydrogen production with solar energy on a huge raft floating on the South Pacific Ocean and for transport of liquefied hydrogen.Since their raft system was found to have some fatal defects in hydrodynamical and structural characteristics, an alternative plan of new raft system was proposed in which those defects are improved.In these papers (three reports will continue after this), authors carried out the feasibility study on the total plan only from technical view point. Economical view point was excluded here.In the first report, a new raft system is proposed as an alternative one. After natural condition such as wave, current and wind of the concerned area (8°S, 138°W) was surveyed, environmental force was estimated and the behavior of the raft was investigated both analytically and experimentally. Detail design of each structural members was conducted under consideration of the structural response for the load mentioned.The new raft system proved to be efficient for collecting solar energy and to be superior in hydrodynamical and structural characteristics.