離岸鋼材現場腐蝕速率監測

On Site Corrosion Rate Monitoring of Offshore Steel

為了解不同強度等級之裸鋼材在台灣海峽環境下之腐蝕速率，配合台電離岸觀測塔興建工程，進行現場腐蝕監測設備之安裝建立，藉由腐蝕資料之蒐集分析，了解三種材料於海洋環境下之腐蝕速率及氣候條件之影響。研究方法包括腐蝕監測設備現場安裝方案及測試、腐蝕探針製作與測試、腐蝕監測設備於離岸觀測塔之安裝、監測數據之下載整理分析與設備維護等。經試驗結果顯示：1.平台上及潮間帶之metal loss（μm）均以S690較低。S355次之，A36較高。2. A36、S355、S690三種不同材質在平台上每個月之腐蝕速率變化程度相當大，變化趨勢一致，與環境中之相對濕度有較高之關聯性。3.潮間帶三種不同材質每個月之腐蝕速率以S690較低。可能由於S690具有緻密內層銹較具保護性。變化趨勢亦一致，經比對結果與環境中之溫度因子較為相近。所建立之腐蝕速率監測技術，未來可應用於監測離岸結構物鋼材於不同高程下之腐蝕性數據，做為發展鋼材與離岸結構物設計之基本數據。

In order to understand the corrosion rates of bare steels with different strength grades in the environment of Taiwan Strait, the corrosion monitoring equipment was established on site on the platform of Tai-Power offshore observation tower. Through collection and analysis of the monitoring data, corrosion rates and environmental effects of three kinds of materials were found. The research methods included on-site installation plan of corrosion monitoring equipments, corrosion probe preparation and testing, corrosion monitoring equipment installed on the offshore observation tower, monitoring data download and analysis , equipment maintenance and so on. The results showed as follows: 1. Metal loss (μm) of S690 on the platform and in the tidal zone is the lowest, S355 followed, and A36 was the highest. 2. Corrosion rates variation of A36, S355, S690 on the platform were quite large every month, but they possessed consistent trends, and had a higher correlation with the relative humidity. 3. The corrosion rate of S690 in tidal zone was lowest per month. Probably due to the S690 has a dense and protective inner rust layer. The trends of corrosion rates of the three materials were also similar, when compared with the variations of the climate factors, it was similar with the temperature factor. The corrosion data of offshore structures under different elevations can be monitored with the established corrosion rate monitoring technology, and be used for the development and design of steel and offshore structures in the future.