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.

scholarly journals Correlation between Flow Accelerated Corrosion and Wall Shear Stress Downstream from an Orifice

2013 ◽  
Vol 7 (3) ◽  
pp. 138-147 ◽  
Author(s):  
Yoichi UTANOHARA ◽  
Yukinori NAGAYA ◽  
Akira NAKAMURA ◽  
Michio MURASE ◽  
Koichi KAMAHORI
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Accelerated Corrosion ◽  
Wall Shear ◽  
Flow Accelerated Corrosion

Prediction of Flow-Accelerated Corrosion/Erosion in High-Speed Ejectors Using a CFD Model

2019 ◽  
Author(s):  
Saurish Das ◽  
Suranjan Sarkar ◽  
Gary H. Lee ◽  
Ong Junxiong
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Droplet Size ◽  
Impact Angle ◽  
Multiphase Model ◽  
Liquid Droplets ◽  
Cfd Model ◽  
Accelerated Corrosion ◽  
Wall Shear ◽  
Flow Accelerated Corrosion

Abstract In high-velocity ejector systems containing liquid droplets, ejector walls are sometimes damaged by flow-accelerated corrosion/erosion. Velocity, droplet size, impact angle etc. are the most important parameters affecting flow-accelerated (FA) corrosion/erosion. In our plant operation, we had experienced FA corrosion/erosion and consequent failure even with very low impact angle. To understand the leak/ failure, we have adopted the Euler-Euler multiphase model-based CFD approach. In the Euler-Euler multiphase model, the liquid droplets are modelled as dispersed phase while the gas-steam is modelled as a continuous phase. To capture the droplet dynamics very accurately, appropriate correlations for drag, lift and wall lubrication force have been chosen. In CFD simulations we have observed liquid film formation at the ejector wall. The liquid film moves along the ejector wall creates a very high wall shear-stress. In the location of high wall shear-stress, one can expect high FA corrosion/erosion and consequent leak. Qualitative comparison of the X-ray image of the actual equipment with the CFD results for wall-shear stress shows very good agreement in terms of predicting leak location. Moreover, we have varied the droplet size and the liquid fraction in the upstream of the ejector. Qualitatively we have observed that with increase in droplet size the material removal rate increases, however, the affected area of the leak decreases. The more liquid in the system increases the wall-shear stress very rapidly. The present CFD model is useful for predicting the leak-prone location and taking predictive actions (e.g. cladding the wall with a high-grade material).

S053074 Relation between Flow Accelerated Corrosion and Wall Shear Stress Downstream from an Orifice in a Circular Pipe

2012 ◽  
Vol 2012 (0) ◽  
pp. _S053074-1-_S053074-4
Author(s):  
Yoichi UTANOHARA ◽  
Yukinori NAGAYA ◽  
Akira NAKAMURA ◽  
Michio MURASE ◽  
Takahiro KIWATA ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Circular Pipe ◽  
Accelerated Corrosion ◽  
Wall Shear ◽  
Flow Accelerated Corrosion

Analysis of Laminar Mixed Convective Plumes Along Vertical Adiabatic Surfaces

1984 ◽  
Vol 106 (3) ◽  
pp. 552-557 ◽  
Author(s):  
K. V. Rao ◽  
B. F. Armaly ◽  
T. S. Chen
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Leading Edge ◽  
Vertical Surface ◽  
Stream Velocity ◽  
Thermal Source ◽  
Flow Conditions ◽  
Velocity Overshoot ◽  
Wall Shear ◽  
Prandtl Numbers

Laminar mixed forced and free convection from a line thermal source imbedded at the leading edge of an adiabatic vertical surface is analytically investigated for the cases of buoyancy assisting and buoyancy opposing flow conditions. Temperature and velocity distributions in the boundary layer adjacent to the adiabatic surface are presented for the entire range of the buoyancy parameter ξ (x) = Grx/Rex5/2 from the pure forced (ξ(x) = 0) to the pure free (ξ(x) = ∞) convection regime for fluids having Prandtl numbers of 0.7 and 7.0. For buoyancy-assisting flow, the velocity overshoot, the temperature, and the wall shear stress increase as the plume’s strength increases. On the other hand, the velocity overshoot, the wall shear stress, and the temperature decrease as the free-stream velocity increases. For buoyancy opposing flow, the velocity and wall shear stress decrease but the temperature increases as the plume’s strength increases.

scholarly journals Analysis of the wall shear stress in a generic aneurysm under pulsating and transitional flow conditions

2020 ◽  
Vol 61 (2) ◽  
Author(s):  
Andreas Bauer ◽  
Maximilian Bopp ◽  
Suad Jakirlic ◽  
Cameron Tropea ◽  
Axel Joachim Krafft ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Transitional Flow ◽  
Flow Conditions ◽  
Wall Shear

Exploring High Frequency Temporal Fluctuations in the Terminal Aneurysm of the Basilar Bifurcation

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Matthew D. Ford ◽  
Ugo Piomelli
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
High Frequency ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Disturbed Flow ◽  
Frequency Fluctuations ◽  
Wall Shear ◽  
Inflow Jet

Cerebral aneurysms are a common cause of death and disability. Of all the cardiovascular diseases, aneurysms are perhaps the most strongly linked with the local fluid mechanic environment. Aside from early in vivo clinical work that hinted at the possibility of high-frequency intra-aneurysmal velocity oscillations, flow in cerebral aneurysms is most often assumed to be laminar. This work investigates, through the use of numerical simulations, the potential for disturbed flow to exist in the terminal aneurysm of the basilar bifurcation. The nature of the disturbed flow is explored using a series of four idealized basilar tip models, and the results supported by four patient specific terminal basilar tip aneurysms. All four idealized models demonstrated instability in the inflow jet through high frequency fluctuations in the velocity and the pressure at approximately 120 Hz. The instability arises through a breakdown of the inflow jet, which begins to oscillate upon entering the aneurysm. The wall shear stress undergoes similar high-frequency oscillations in both magnitude and direction. The neck and dome regions of the aneurysm present 180 deg changes in the direction of the wall shear stress, due to the formation of small recirculation zones near the shear layer of the jet (at the frequency of the inflow jet oscillation) and the oscillation of the impingement zone on the dome of the aneurysm, respectively. Similar results were observed in the patient-specific models, which showed high frequency fluctuations at approximately 112 Hz in two of the four models and oscillations in the magnitude and direction of the wall shear stress. These results demonstrate that there is potential for disturbed laminar unsteady flow in the terminal aneurysm of the basilar bifurcation. The instabilities appear similar to the first instability mode of a free round jet.

Distribution of Mass Transfer Rate and Wall Shear Stress Behind Simple Rectangular Stenosis in Pulsating Flow

1989 ◽  
Vol 111 (1) ◽  
pp. 47-54 ◽  
Author(s):  
R. Yamaguchi
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Transfer Rate ◽  
Schmidt Number ◽  
Fluid Dynamic ◽  
Mass Transfer Rate ◽  
Pulsating Flow ◽  
Flow Through ◽  
Wall Shear

The distributions of mass transfer rate and wall shear stress in sinusoidal laminar pulsating flow through a two-dimensional asymmetric stenosed channel have been studied experimentally and numerically. The distributions are measured by the electrochemical method. The measurement is conducted at a Reynolds number of about 150, a Schmidt number of about 1000, a nondimensional pulsating frequency of 3.40, and a nondimensional flow amplitude of 0.3. It is suggested that the deterioration of an arterial wall distal to stenosis may be greatly enhanced by fluid dynamic effects.

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.

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