Flow and mass transfer downstream of an orifice under flow accelerated corrosion conditions

2012 ◽  
Vol 252 ◽  
pp. 52-67 ◽  
Author(s):  
Wael H. Ahmed ◽  
Mufatiu M. Bello ◽  
Meamer El Nakla ◽  
Abdelsalam Al Sarkhi
Keyword(s):  
Mass Transfer ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion

Flow and Mass Transfer in Bends Under Flow-Accelerated Corrosion Wall Thinning Conditions

2009 ◽  
Author(s):  
John M. Pietralik ◽  
Chris S. Schefski
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Conditions ◽  
Ferrous Ions ◽  
Local Flow ◽  
Accelerated Corrosion ◽  
Flow Effects ◽  
Flow Accelerated Corrosion

The three groups of parameters that affect flow-accelerated corrosion (FAC) are flow conditions, water chemistry, and materials. Nuclear power plant (NPP) data and laboratory tests confirm that under alkaline water chemistry there is a close relationship between local flow conditions and FAC rates in piping components. The knowledge of local flow effects can be useful for developing targeted inspection plans for piping components, predicting the location of the highest FAC rate for a given piping component, and determining what piping components should be replaced. A similar evaluation applies also to FAC in heat transfer equipment such as heat exchangers and steam generators. The objective of this paper is to examine the role of flow and mass transfer in bends under FAC conditions. Bends experience increased FAC rates compared to straight pipes, and are the most common components in piping systems. When the flow effects are dominant, the FAC rate is proportional to the mass flux of ferrous ions, which, in turn, is proportional to the mass transfer coefficient in the flowing water. The mass transfer coefficient describes the intensity of the transport of corrosion products (ferrous ions) from the oxide-water interface into the bulk water. Therefore, this parameter can be used for predicting the local distribution of the FAC rate. The current paper presents plant and laboratory evidence of the relationship between local mass transfer conditions and the FAC rate in bends. It shows correlations for mass transfer coefficients in bends and reviews the most important flow parameters affecting the mass transfer coefficient. The role of bend geometry and, in particular, the short and long radii, surface roughness, wall shear stress, and local turbulence is discussed. Computational fluid dynamics calculations and plant artefact measurements for short-radius and long radius bends are presented. The effect of the close proximity of two bends on FAC rate is also examined based on CANDU™ NPP inspection data and compared with literature data.

Validation of Code System DRAWTHREE-FAC for Evaluation of Wall Thinning due to Flow Accelerated Corrosion by PWR Feed Water Piping Analysis

2011 ◽  
Author(s):  
Masanori Naitoh ◽  
Shunsuke Uchida ◽  
Hidetoshi Okada ◽  
Seiichi Koshizuka
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Flow Behavior ◽  
Feed Water ◽  
Code System ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Flow Accelerated Corrosion

The code system DRAWTHREE-FAC for evaluation of pipe wall thinning due to flow accelerated corrosion was validated by comparison of calculations with measurements at the secondary piping of a PWR plant. Distributions of flow velocity and temperature along the whole piping were calculated with the system code RELAP5 and corrosive conditions were calculated by a N2H4-O2 reaction analysis code. Precise flow turbulence at major parts of the piping was analyzed with a 3D computational fluid dynamics (CFD) code to obtain mass transfer coefficients at structure surfaces. In the CFD calculation, the κ-ε method was applied. Since the κ-ε method can not give detailed flow behavior in a boundary layer, the results were extrapolated with a wall function, a power law, and analogy of non-dimensional numbers to obtain mass transfer coefficients in the boundary layer. Then, wall thinning rates were calculated by coupling models of static electrochemical and dynamic oxide layer growth. The wall thinning calculation was focused on T-junction portions of a PWR feed water line. The wall thickness of the PWR secondary piping was measured by the ultrasonic testing. The calculated residual wall thicknesses after thinning agreed with the measurements within ±20% difference.

A110 Study of Mass Transfer Effect on Flow Accelerated Corrosion

2008 ◽  
Vol 2008.13 (0) ◽  
pp. 21-22
Author(s):  
Kimitoshi YONEDA ◽  
Fumio INADA ◽  
Ryo MORITA ◽  
Kazutoshi FUJIWARA ◽  
Masahiro FURUYA
Keyword(s):  
Mass Transfer ◽  
Transfer Effect ◽  
Accelerated Corrosion ◽  
Mass Transfer Effect ◽  
Flow Accelerated Corrosion

scholarly journals Flow-Accelerated Corrosion of Type 316L Stainless Steel Caused by Turbulent Lead–Bismuth Eutectic Flow

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 627 ◽  
Author(s):  
Tao Wan ◽  
Shigeru Saito
Keyword(s):  
Mass Transfer ◽  
Stainless Steel ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
316L Stainless Steel ◽  
Straight Tube ◽  
Accelerated Corrosion ◽  
Corrosion Depth ◽  
Cfd Analyses ◽  
Flow Accelerated Corrosion

Lead–bismuth eutectic (LBE), a heavy liquid metal, is an ideal candidate coolant material for Generation-IV fast reactors and accelerator-driven systems (ADSs), but LBE is also known to pose a considerable corrosive threat to its container. However, the susceptibility of the candidate container material, 316L stainless steel (SS), to flow-accelerated corrosion (FAC) under turbulent LBE flow, is not well understood. In this study, an LBE loop, referred to as JLBL-1, was used to experimentally study the behavior of 316L SS when subjected to FAC for 3000 h under non-isothermal conditions. An orificed tube specimen, consisting of a straight tube that abruptly narrows and widens at each end, was installed in the loop. The specimen temperature was 450 °C, and a temperature difference between the hottest and coldest legs of the loop was 100 °C. The oxygen concentration in the LBE was lower than 10−8 wt %. The Reynolds number in the test specimen was approximately 5 × 104. The effects of various hydrodynamic parameters on FAC behavior were studied with the assistance of computational fluid dynamics (CFD) analyses, and then a mass transfer study was performed by integrating a corrosion model into the CFD analyses. The results show that the local turbulence level affects the mass concentration distribution in the near-wall region, and therefore, the mass transfer coefficient across the solid/liquid interface. The corrosion depth was predicted on the basis of the mass transfer coefficient obtained in the numerical simulation and was compared with that obtained in the loop. For the abrupt narrow part, the predicted corrosion depth was comparable with the measured corrosion depth, as was the abrupt wide part after involving the wall roughness effects in the prediction; for the straight tube part, the predicted corrosion depth is about 1.3–3.5 times the average experimental corrosion depth, and the possible reason for this discrepancy was provided.

Disturbed Flow and Flow-Accelerated Corrosion in Oil and Gas Production

1998 ◽  
Vol 120 (1) ◽  
pp. 72-77 ◽  
Author(s):  
K. D. Efird
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Oil And Gas ◽  
Steel Corrosion ◽  
Flow Conditions ◽  
Accelerated Corrosion ◽  
Disturbed Flow ◽  
Wall Shear ◽  
Flow Accelerated Corrosion

The effect of fluid flow on corrosion of steel in oil and gas environments involves a complex interaction of physical and chemical parameters. The basic requirement for any corrosion to occur is the existence of liquid water contacting the pipe wall, which is primarily controlled by the flow regime. The effect of flow on corrosion, or flow-accelerated corrosion, is defined by the mass transfer and wall shear stress parameters existing in the water phase that contacts the pipe wall. While existing fluid flow equations for mass transfer and wall shear stress relate to equilibrium conditions, disturbed flow introduces nonequilibrium, steady-state conditions not addressed by these equations, and corrosion testing in equilibrium conditions cannot be effectively related to corrosion in disturbed flow. The problem in relating flow effects to corrosion is that steel corrosion failures in oil and gas environments are normally associated with disturbed flow conditions as a result of weld beads, pre-existing pits, bends, flanges, valves, tubing connections, etc. Steady-state mass transfer and wall shear stress relationships to steel corrosion and corrosion testing are required for their application to corrosion of steel under disturbed flow conditions. A procedure is described to relate the results of a corrosion test directly to corrosion in an operation system where disturbed flow conditions are expected, or must be considered.

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