C214 流れ加速型腐食の予測手法の開発(3) : 予測モデル式におけるレイノルズ数依存性の検討(配管減肉評価法(1),OS5 保全・設備診断技術),動力エネルギーシステム部門20周年,次の20年への新展開)

概要

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Flow Accelerated Corrosion (FAC) requires considerable attention in plant piping management, for its potential of catastrophic pipe rupture of main piping systems. In view of fluid dynamics, the most essential factor to be considered is mass transfer at the inner surface of the pipe. In the previous report, the authors have proposed a new mass transfer coefficient model, which is adaptable to various types of piping elements with strong turbulence, by introducing the idea of "Effective Friction Velocity" from the hydraulics in the viscous sub-layer along the wall. And in the present report, the model has been revised to improve the prediction accuracy of FAC thinning rate, quantitatively. In this revision process, FAC experimental data with AVT water condition of various pH values and CFD data for the flow in the experiments were applied. As the result, the exponent of Reynolds number in the mass transfer coefficient model was changed from 0.75 to 0.88, as a main item in the revision. In addition, diffusivity of dissolved iron and impact factor for turbulence consideration were also varied for the improvement.
2010-06-20