Analytical Investigation of Deaerator Steam Inlet Nozzle Corrosion Allowance in a CANDU Station

Author(s):  
Ali Keshavarz ◽  
Andrew K. Ali ◽  
Randy K. Lall

Flow-accelerated corrosion (FAC) is a phenomenon that results in metal loss from piping, vessels and equipment made of carbon steel. This metal loss can lead to stress to occur at the steam inlet nozzle side, where it is located at the side of the deaerator. This paper presents a method to find the thickness critical of the steam inlet nozzle. A Finite Element (FE) model of the pressure vessel head was created to perform a stress analysis using NX Nastran 5.0. By applying materials properties, loads and constraints to the model, the results obtained are required to satisfy the following criterion: vonMises≥SySy=YieldStrength The results obtained from the stress analysis were analyzed to obtain a corrosion allowance and it was compared to the recommended value from a normal deaerator design, which is roughly 0.25 inches. From the FE model, and by continuously reducing the thickness of the nozzle, it was determined that the corrosion allowance is 0.229 inches, and that the percentage error was 8.4%.

2014 ◽  
Vol 39 (8) ◽  
pp. 6435-6451 ◽  
Author(s):  
Rani Hari Ponnamma ◽  
Divya Teegala ◽  
Sahaya Ravi Ranjan ◽  
Vivekananda Kain ◽  
Barua Dipak Kumar

2012 ◽  
Vol 429 (1-3) ◽  
pp. 226-232 ◽  
Author(s):  
J.L. Singh ◽  
Umesh Kumar ◽  
N. Kumawat ◽  
Sunil Kumar ◽  
Vivekanand Kain ◽  
...  

Author(s):  
Ruixuan Han ◽  
Yi Peng ◽  
Huailin Li

A new prediction model for the oxidation layer thickness of carbon steel is developed, that is based on the parabolic time law of corrosion and the mass transport balance theory. The relationship between the oxidation layer thickness and temperature, pH, and flow velocity is discussed. The predicted results show that the oxidation layer thickness increases exponentially with increasing temperature and decreases exponentially with increasing flow velocity. The oxidation layer thickness increases with increasing pH until pH=10.5 and then decreases. The predicted results agree with experimental results.


2012 ◽  
Vol 11 (6) ◽  
pp. 257-262
Author(s):  
Tae Jun Park ◽  
Eun Hee Lee ◽  
Kyung Mo Kim ◽  
Hong Pyo Kim

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Yunze Xu ◽  
Qiliang Zhang ◽  
Qipiao Zhou ◽  
Shan Gao ◽  
Bin Wang ◽  
...  

AbstractIn this work, flow accelerated corrosion (FAC) and erosion−corrosion of marine carbon steel in natural seawater were electrochemically studied using a submerged impingement jet system. Results show that the formation of a relatively compact rust layer in flowing natural seawater would lead to the FAC pattern change from ‘flow marks’ to pits. The increase of the flow velocity was found to have a negligible influence on the FAC rate at velocities of 5−8 m s−1. The synergy of mechanical erosion and electrochemical corrosion is the main contributor to the total steel loss under erosion−corrosion. The increase of the sand impact energy could induce the pitting damage and accelerate the steel degradation. The accumulation of the rust inside the pits could facilitate the longitudinal growth of the pits, however, the accumulated rusts retard the erosion of the pit bottom. The erosion and corrosion could work together to cause the steel peeling at the pit boundary. The steel degradation would gradually change from corrosion-dominated to erosion-dominated along with the impact energy increasing.


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