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| #$NPNumerical Simulation of Sacrificial Anode Cathodic Protection for Offshore Pile Foundation Platform in Service |
| Received:September 30, 2020 Revised:October 25, 2020 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.01.017 |
| KeyWord:pile foundation platform sacrificial anode cathodic protection water resistance potential distribution numerical simulation |
| Author | Institution |
| ZHOU Bing |
CNPC Engineering Technology Research Co., Ltd, Tianjin , China;Key Laboratory of CNPC Tubular Goods Engineering, Tianjin , China |
| ZHAO Yu-fei |
CNPC Engineering Technology Research Co., Ltd, Tianjin , China;Key Laboratory of CNPC Tubular Goods Engineering, Tianjin , China |
| ZHANG Ying-ying |
CNPC Engineering Technology Research Co., Ltd, Tianjin , China;Key Laboratory of CNPC Tubular Goods Engineering, Tianjin , China |
| HAN Wen-li |
CNPC Engineering Technology Research Co., Ltd, Tianjin , China;Key Laboratory of CNPC Tubular Goods Engineering, Tianjin , China |
| WANG Shun |
Engineering & Design Institute of CPOE, Beijing , China |
| DONG Liang |
Changzhou University, Changzhou , China |
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| Abstract: |
| The analysis on the ground resistance of sacrificial anode and the protection effects and construction volumes of different sacrificial anode schemes for the offshore pile foundation platform in shallow sea provides guidance for the design of sacrificial anode cathodic protection of the offshore pile foundation platform. The anode-to-sea resistance and the protection effects of different protection schemes in the design of the sacrificial anode cathodic protection system for the offshore pile foundation platform are simulated and calculated with BEASY CP software. The results show that in the sea area of the offshore pile foundation platform, the anode-to-sea resistances are close and small when single sacrificial anode is placed above 0.25 m of sea water/mud interface and below 1.35 m of sea water surface. Such resistances are about 0.048 Ω, which is about 26% higher than that calculated by the standard recommended formula. The anode-to-sea resistance of multiple anodes combination decreases with the increase of anode number or anode spacing. However, due to crowding effect, it is significantly higher than that of ideal parallel connection resistance for multiple anodes. A total of six sacrificial anode schemes with different combined anodes in different locations are given where the sacrificial anodes are placed at 0.8 m away from the sea water/mud interface with single and multiple anodes. The calculation results show that the protection potential distribution range of pile foundation platform under different sacrificial anode schemes is close, which is between ‒680 mV and ‒1080 mV (CSE). The difference of protection effect of different schemes is mainly reflected in the protection of main piles and risers in highly corrosive areas including the sea and near the sea water/mud interface. With the transformation of anode from five combined anodes scheme and three combined anodes scheme to single anode scheme, the total output current of sacrificial anodes increases from 110 to 133 A. The protection distance of main pile in sea mud increases from 5~8 m to 5~10 m, and the protection distance of riser in sea mud increases from 0~3 m to 4~7 m. The maximum output current of the two anodes in scheme 1 of five combined anodes is about twice that of the middle anode, and the output current of each sacrificial anode in scheme 2 of three combined anodes is equivalent. The number, combination and position of sacrificial anode can be optimized to achieve more uniform protection potential distribution with numerical simulation. In this paper, the three combined anode schemes 2 proposed have the characteristics of protection effect, uniformity of anode output current and relatively small construction amount, which can be used as the recommended scheme for sacrificial anode cathodic protection of offshore pile foundation platform. |
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