15 Corrosion Testing under Moderate and High

Laboratory Test Methods for Corrosion Testing Under Moderate and High Shear Conditions
Hunter Thomson, Matthew McCall, Deborah Bowering, Gordon Graham
Scaled Solutions Limited, 6 Nettlehill Road, Livingston, EH54 5DL, United Kingdom
Paper for Presentation at the 26th International Oilfield Chemistry Symposium 2015, Geilo, Norway,
22–25 March 2015
Abstract
In both materials selection and in the application of corrosion inhibitors for the protection of oil and gas
infrastructure, conditions can arise where fast flowing fluids result in very high shear, turbulent
conditions (e.g. at constrictions such as valves and in-flow control devices). Effectively preventing
corrosion under these high shear conditions is therefore of critical importance.
A range of laboratory test methods exists for generating moderate and high shear environments in
which to assess chemicals and materials for field application. Common test methods such as rotating
cylinder electrode (RCE) and rotating cage autoclave (RCA) tests can provide useful data at moderate
shear stresses (up to 100 Pa), while more complex methods such as jet impingement (JI) can be used to
generate significantly higher shear stresses.
Recently we have developed a range of more advanced laboratory test methods for the assessment of
materials and production chemicals, including corrosion and scale inhibitors, at very high shear stresses
up to 10,000 Pa using both weight loss and electrochemical (LPR) approaches. Conducting these tests
in conjunction with more common moderate shear RCE and RCA tests allows us to build-up a picture
of how different materials and chemicals perform with increasing shear stress. The development of
electrochemical LPR approaches under the high shear conditions (JI-LPR) and under HP/HT autoclave
conditions allows results to be generated more rapidly, while allowing more detailed evaluation of the
film forming process to be evaluated than would otherwise be achievable by more conventional weight
loss approaches. In this work the higher shear electrochemical JI has been compared with the more
conventional weight loss JI, and also other techniques to validate the approach.
The application of these advanced laboratory methods to assess materials performance and the effect of
corrosion inhibitors under increasingly higher shear conditions is currently playing a vital role in
evaluating the performance of materials and production chemicals for very challenging conditions,
prior to field application. Furthermore, the ability to conduct these tests under increasingly higher
pressures and temperatures is also of importance to enable field conditions to be matched in the
laboratory.
Introduction
The corrosion rate of a metal is not purely dependant on electro-chemical processes but can also be
significantly affected by the force exerted by fluid flowing at its surface [1]. It is well known that
corrosion tends to be more severe around bends than in straight sections due to the change in fluid
velocity leading to an increase in shear stress [2]. The use of in-flow control valves (ICVs) and in-flow
control devices (ICDs) to improve production has become increasingly common in recent years. The
small apertures combined with the high flow in these systems can result in very high shear regimes and
increased turbulence. This accelerated fluid flow can lead to enhanced corrosion rates due to removal
of protective corrosion by-products from the metal surface, whilst also bringing corrosive species into
contact with the unprotected surface. If a corrosion inhibitor is similarly affected this can lead to
catastrophic failure in an otherwise well controlled system [1].
As a result of this risk of accelerated corrosion rates, various laboratory tests have been developed to
study the effects of increasing shear on corrosion [3]. A schematic of three available techniques is
shown in Figure 1, illustrating the location and shape of a typical test specimen or specimens, and the
direction of fluid flow within the system. Digital images displaying the main aspects of the different
techniques being considered here are also provided in Figure 2 (a)-(e).
-1-
Figure 1: Schematic representation of the techniques used
Rotating Cylinder
Electrode
Rotating Cage
Jet Impingement
Key
Test
specimen
Direction
of fluid
flow
Figure 2: Digital images of the techniques used
2(a) LPR Bubble Test
2(b) Rotating Cage
0 Pa
90°C, 1 bar
LPR
2(c) Rotating Cylinder Electrode (RCE)
Up to 80 Pa
90°C, 1 bar
LPR, Pitting
Up to 80 Pa
200°C, 300 bar
Weight Loss, Pitting
2(d) Jet Impingement (Standard Set-up)
2(e) Jet Impingement (Autoclave Set-up)
Inlet line from
Inlet
line from
reservoir
via
reservoir via
pump
pump
Outlet line to
PRV
Inlet line from
reservoir via
pump
JetJet Nozzle
Coupon
Coupon
Electrical connections
for LPR
0 – 400 Pa
90°C, 1 bar
LPR, Weight Loss, Pitting
Up to 10,000 Pa
100°C, 200 bar
LPR, Weight Loss, Pitting
-2-
Rotating cage tests can readily achieve shear stresses up to ca. 100 Pa but are prone to vortex formation
with irregular flow dynamics which can lead to variability within the test – i.e. formation of pits on
some test pieces [4] and uneven shear stresses across the surface’s leading to uneven corrosion.
Rotating cylinder electrode (RCE) tests allow for more easily modelled flow dynamics but are again
limited to a single shear stress up to ca. 100 Pa.
The need to evaluate higher shear systems in a laboratory setting led to the development of the jet
impingement (JI) test methodology [5]. This technique allows for testing at much higher shear stresses
(e.g. up to ca. 10000 Pa in our laboratories). The flow regime caused by a jet impinging on a flat plate
placed perpendicular to the jet can be divided into three regions; A stagnation region where the velocity
is largely perpendicular to the plate surface, a wall jet region where the velocity is largely parallel to
the plate, and the hydrodynamic boundary region where the flow rate and turbulence decrease rapidly.
These three regions can provide good analogues for a variety of systems. The flow rate, jet nozzle size
and test piece can all be readily altered to tailor the shear stresses or flow regime desired. A plot
displaying the variation in shear stress with radial distance across the coupon surface in a typical jet
impingement test is displayed in Figure 3 below.
Figure 3: Plot displaying variation in shear stress with radial distance in a typical jet impingement test.
Note: Plot displays only the stagnation and wall jet region. The hydrodynamic boundary region is omitted.
High shear regimes such as those experienced in and around ICDs and ICVs can also dramatically
affect scale formation, since it is a kinetically controlled process. This can include a theoretically
“non-scaling” brine composition becoming problematic at restrictions within the system where shear
stress and turbulence increase. The JI technique described here has also been shown to be effective in
the assessment of scale formation, and investigations using the technique have shown both increases in
scaling tendency and a change in scale composition at increased shear stress [6].
Method Development
Initial works examined conventional weight loss JI analysis and compared results against other weight
loss approaches. At this time the general consensus was that due to a combination of the uneven flow
dynamics and difficulties in maintaining electrical connections within the JI set up that simple
electrochemical LPR measurements were less reliable. This work therefore set out to develop reliable
electrochemical JI measurements utilising both two and three electrode set-ups, initially for moderate
shear LPR tests and limited to ambient pressure (maximum temperature ~ 90°C). These tests were
conducted using conventional glass cells, similar to that used in conventional bubble tests (see Figure
2(d)). Alongside this work higher shear techniques were being developed at shear stresses up to 10,000
Pa and at elevated temperatures and pressures using newly designed HP/HT JI autoclaves (see Figure
2(e)). These served a number of purposes; firstly by enabling tests to be conducted at elevated
temperatures and pressures, and also served to overcome a potential uncertainty in the lower pressure
-3-
set-up, whereby gas bubbles and cavitation could potentially occur due to the differential pressures
across the injection nozzle itself when testing at higher shears.
The final stage then came to introduce the electrochemical LPR measurements into the JI Autoclaves
by utilising HP electrical connectors. This proved the most challenging with various prototypes being
required both under the lower pressure “bubble cell” approach and also for the higher pressure / higher
shear autoclave approach. Results described in this paper only show results for the final design and
serve to demonstrate the increased amount of information relating to the kinetics of the corrosion
process and the impact of either protective films and / or film forming inhibitors that is generally
achieved with electrochemical processes, and also demonstrates that even at extremely high shears of ~
10,000 Pa electrochemical approaches can still be used to provide accurate corrosion measurements /
corrosion inhibitor performance measurements over short timeframes (typically ~ 24 hour test runs),
which represents a considerable advantage over longer term weight loss measurements.
Experimental Methods
Test conditions
The corrosion rates of two metallurgies (C1018 and L80-13Cr Steel, see Table 2) were measured at a
range of shear stresses. The performance of a generic corrosion inhibitor was also assessed for its
ability to mediate the corrosion of C1018 steel. Three test techniques were used in this project; 2electrode LPR bubble tests, 3-electrode RCE-LPR tests and 3-electrode JI-LPR tests for the ambient
pressure “bubble cell” moderate shear JI conditions (up to 400Pa) and a 2-electrode cell for the higher
shear (10,000 Pa) HP/HT Autoclave JI conditions . The test conditions are summarised below.
Brine Chemistry
Representative of a typical 50:50 formation water:sea water mix from the Gulf region. Note: brine
prepared with sulphate anions omitted to prevent scale formation.
Table 1: Brine Chemistry
Ion
mg/l
Na+
32000
Ca2+
5750
Mg2+
1500
Sr2+
400
[HCO3]100
Temperature
Pressure
Brine
Gas
Metallurgy
Techniques
Test Duration:
Shear Stress
Analysis
pH
80°C
Ambient
See Table 1
1bar 100% CO2
C1018, L80-13Cr – see Table 2
Bubble test, RCE, JI
18 hours (bubble tests and RCE tests), 48 hours (JI tests)
0, 40, 80, 200 and 400 Pa & 10,000 Pa
Linear Polarisation Resistance (LPR)
Weight-loss
unadjusted, measured as 5.1-5.3 under test conditions
Table 2: Compositions of the Metals Used in this Project
Element
C1018
L80-13Cr
Composition (%) Composition (%)
Aluminium
0.024
Carbon
0.016
0.21
Cobalt
0.016
Chromium
13.03
Copper
0.087
Manganese
0.74
0.53
Molybdenum
0.025
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Nitrogen
Neodymium
Nickel
Phosphorus
Sulphur
Silicon
Vanadium
0.013
0.01
0.22
-
0.0308
0.026
0.169
0.015
0.003
0.31
0.019
Analysis
LPR measurements were conducted using a two or three electrode setup with a scanning range from –
10 to +10 mV (with respect to the open circuit potential) and a scanning rate of 30 mV/ min with
readings taken every 30 minutes over an 18 hour period. Coupon weight loss analysis was carried out
on the electrodes used for RCE-LPR and JI-LPR tests following the ASTM standard [7].
JI Shear Stress Calculation
The JI test method used is based upon ASTM Standard G208 [5]. This describes how the velocity of
the test fluid changes as it radiates out along the test coupon. Near to the jet the flow is largely axial
changing rapidly to become parallel to the surface of the test coupon, this region is of little use for
correlation to pipe flow conditions so for standard corrosion tests this section is removed (hole of
radius 1.5 x the jet radius) and plugged with an inert plastic (PEEK) or epoxy resin flush to the coupon
surface. From the point of maximum velocity and minimum jet thickness at approximately 2 radial
distances to 4 radial distances the shear stress exerted is mathematically defined as:
 w  0.1788    U  Re
2
0
0.182
r
 
 r0 
2.0
Where:
Re 
τw
ρ
U0
r
r0
Re
υ
=
=
=
=
=
=
=
2r0 U 0

wall shear stress (N/m2),
density (kg/m3),
velocity (m/s) of the flow at the position of leaving the nozzle,
distance from stagnation point (m),
jet nozzle radius (m),
Reynold’s number, and
kinematic viscosity (viscosity/density) of the testing liquid (m2/s)
The shear stress quoted throughout this report for JI tests is that found at r = 2r0; the point of maximum
flow and minimum jet thickness.
Results and Discussion
1) C1018 Testing
The results for all test conducted with C1018 are summarised in Table 3, below. The corrosion rates
(CR) obtained by LPR analysis are given as those measured at the end of the 18 hour test and also
averaged over the full duration of the test (Note: test duration ranged from 18 – 48 hours). While the
corrosion rate observed after 18 hours is typically used to assess the performance of a corrosion
inhibitor in electrochemical corrosion tests, for the purpose of this discussion the average corrosion rate
over the entire test duration provides a more direct comparison to that obtained by weight-loss analysis.
Shear stresses for the different techniques were selected to provide a direct comparison between test
methods in the shear stress region in which they overlap, while also looking at the higher shear stresses
capable with jet impingement.
-5-
Table 3: Summary of Results of C1018 Testing
Test Method
Shear Stress
(Pa)
Bubble Test
0
RCE
JI
Autoclave JI
40
40
80
80
40
40
80
80
200
400
CI Concentration
(ppmv)
0
10
30
50
0
30
0
30
0
30
0
30
0
0
10000
0
Corrosion Rate (CR)
LPR
Weight
Loss *
18h
Average
5.63
5.06
0.15
0.90
0.05
0.71
0.04
0.64
9.10
8.51
7.41
0.39
1.28
1.32
7.65
8.05
6.15
0.33
1.30
1.30
2.99
3.75
3.12
0.96
1.53
1.37
2.11
3.82
2.55
0.94
1.57
1.52
7.50
7.79
7.50
7.49
7.35
8.16
10.43
9.37
-
* Note due to the change in corrosion profiles observed with time the weight loss corrosion rates are
compared with the “average” LPR measurements observed throughout the test time.
(i) C1018 – LPR Bubble Tests
To provide an initial baseline under pseudo-static conditions, LPR bubble tests were conducted with a
generic corrosion inhibitor (CI) at a range of concentrations in order to obtain the minimum effective
dose (MED) for C1018 steel. The concentrations tested were chosen to be representative of those
typically used in practise under these types of conditions. A corrosion rate of ≤ 0.1mm/y was selected
as the pass criterion to be achieved at the MED as this is commonly used in laboratory assessments of
CI performance, and as a typical acceptable corrosion rate in field applications. The results of these
tests are plotted in Figure 4, below, with corrosion rate plotted on a logarithmic scale on the y-axis,
against time in hours on the x-axis.
-6-
A blank test with no CI added gave a final corrosion rate of ca. 5.63 mm/y; the corrosion rate did not
vary a great deal over the test with an average corrosion rate of ca. 5.06 mm/y. The CI was then tested
at three concentrations; 10, 30 and 50 ppmv. The MED for this chemical was determined to be 30
ppmv, achieving a corrosion rate of ca. 0.05 mm/y at the end of the 18 hour test, corresponding to a ca.
99% reduction in corrosion rate relative to the blank test. It is worth noting that this chemical took
approximately 3 hours to achieve a corrosion rate ≤ 0.1 mm/y following addition, indicative of slow
formation of the protective layer.
(ii) C1018 – RCE Tests
Using the MED determined in Part (i) the performance of the corrosion inhibitor was further assessed
in RCE tests conducted at 40 and 80 Pa. Blank tests with no CI added were also performed at these
shear stresses. The results of these tests are displayed graphically in Figure 5, below.
The corrosion rates obtained from the blank tests were very similar at both 40 and 80 Pa with an
average corrosion rate of ca. 8.5 and 8.0 mm/y respectively, over the course of the 18 hour test.
Comparing the blank RCE tests to that from the bubble tests shows an increase in corrosion rate with
increased shear stress under the test conditions; ca. 8 mm/y at increased shear (40 – 80 Pa) vs. 5 mm/y
at 0 Pa. However, when comparing the blank RCE tests at 40 and 80 Pa there is very little difference in
the corrosion rates observed, suggesting that there is a non-linear relationship between corrosion rate
and shear under these conditions.
When the CI was employed in the RCE tests at the MED determined in the bubble tests (30 ppmv),
final corrosion rates of ca 0.39 and 0.33 mm/y were observed at shear stresses of 40 Pa and 80 Pa,
respectively. The concentration tested did not meet the pass criterion under either shear stress,
indicating a reduction in CI performance at these moderate shear stresses.
As discussed in Part (i), in the static bubble tests the chemical displayed an initial sharp drop in
corrosion rate followed by a relatively slow improvement in inhibition at this concentration over the
duration of the test. This gradual improvement in performance could be due to numerous factors
including the dispersion of the chemical, and the persistency of the film formed. However, in the RCE
tests the corrosion rate also displayed a sharp drop 30 minutes after CI addition, but displayed no
further reduction over the remainder of these higher shear tests. These results suggest that
dispersibility is not the critical factor for the performance of this chemical, but that the increased shear
prevents this chemical from building up a more protective layer on the metal surface over time;
therefore shear is affecting film formation ability of the tested CI under these conditions.
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(iii) C1018 - JI Tests
Similarly to the RCE tests, JI tests were performed at 40 and 80 Pa in the absence of CI and at the
previously determined MED of the CI. Additional tests with no CI present were also performed at 200,
400 and 10000 Pa. Results are displayed graphically in Figure 6, below.
At 40 and 80 Pa average corrosion rates of ca. 3.8 mm/y were observed in the blank tests with no
chemical present. This is a lower corrosion rate than observed in the RCE tests (8-8.5 mm/y).
However, when the tests conducted in the presence of CI are compared then the converse is true; the
corrosion rates observed at the end of the 18 hour tests are ca. 0.96 and 0.94 mm/y for the 40 and 80 Pa
JI-LPR tests respectively, significantly higher than the equivalents in the RCE tests. This is thought to
relate to poorer film adherence under the flow dynamics of the JI system.
When higher shear stresses are tested (200 and 400 Pa), the corrosion rate in the absence of any
inhibitor increases to ca. 7.5-8.2 mm/y, in the region of those measured in lower shear RCE tests.
There is some evidence, both from the electrochemical trends and also post treatment microscopic
analysis of the coupons, to suggest that a partially protective corrosion product film may be forming on
the C1018 metal surface under the jet impingement flow regime, with initially higher corrosion rates
dropping off particularly over the first 2 hours of the tests. This was not apparent in the bubble tests or
RCE tests. The difference in flow regimes for the RCE and JI tests may also account for the reduction
in performance of the CI when employed in the JI tests. Moving to the extremely high shear 10000 Pa
conditions, a further increase in corrosion rate to ca. 9-10 mm/y is observed.
The main conclusion is that the electrochemical approaches and the weight loss approaches for the JI
set up are internally consistent. The JI data also shows a clear trend of increasing shear leading to
increased corrosion but with a generally non-linear approach. The results in terms of corrosion rate
appear to plateau at moderate shears, with only a relatively small change observed when moving from
approximately 200-400 Pa up to the ultra-high shear 10,000 Pa tests.
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2) L80-13Cr Testing
The results for all L80-13Cr testing are summarised in Table 4, below.
Table 4: Summary of Results of L80-13Cr Testing
LPR Corrosion Rate
Shear Stress
Test Method
(Pa)
18h
Average
Bubble Test
0
0.017
0.014
40
0.021
0.022
RCE
80
0.032
0.031
40
0.12
0.12
JI
80
0.13
0.13
400
0.14
0.17
Autoclave JI
10000
-
-
Weight Loss
CR
<0.1
<0.1
0.24
0.08
0.15
0.40
(i) L80-13Cr – Bubble Tests and RCE Tests
Bubble tests were initially performed to obtain a pseudo-static baseline corrosion rate. RCE tests were
performed at 40 and 80 Pa. The results of these tests are displayed graphically in Figure 6, below, with
corrosion rate plotted on a logarithmic scale on the y-axis, against time in hours on the x-axis.
As would be expected for a corrosion resistant alloy such as L80-13Cr, these results indicate relatively
low corrosion rates for this metal composition at shear stresses up to 80 Pa, significantly less than 0.1
mm/y in all cases.
(ii) L80-13Cr – JI Tests
JI-LPR tests were performed at 40, 80 and 400 Pa, with the results for these tests displayed graphically
in Figure 8, below.
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JI test results indicate significantly higher corrosion rates for L80-13Cr compared with the RCE testing
at equivalent wall shear stresses (40-80 Pa), with average corrosion rates in the region of 0.1-0.2 mm/y
compared with ~ 0.02-0.03 mm/y for the RCE approaches. These results could again be attributed to
differences of the flow regimes from the two different test methodologies, whereby the JI methodology
creates a more severe environment due to the gradient in shear stress across the high shear transition
zone caused by the impinging fluid. We consider that for the JI approach the protective films may be
damaged due to different flow regimes close to the surface.
Moving to the higher shear 400 Pa JI-LPR tests there is no indication of a relationship of increasing
corrosion rate with increasing wall shear stress under these conditions, with corrosion rates of 0.1-0.2
mm/y observed, which are still consistent with those observed at 40 and 80 Pa. However, under the
extremely high shear 10000 Pa conditions, an increase in corrosion rate to ca. 0.4 mm/y is observed.
Summary and Conclusions
Due to the need to assess corrosion in challenging environments in oil and gas field applications, a
range of techniques have been used and developed to investigate the impact of wall shear stress at a
metal surface on corrosion rate. These laboratory tests can provide useful information on the
performance of both materials of construction and production chemicals such as corrosion inhibitors, in
locations of higher wall shear such as fast flowing fluids in pipelines, particularly at bends and
restrictions, and through small orifices such as ICDs and ICVs.
Work in this paper has focussed on the development of high shear (200 – 400 Pa) and ultra-high shear
(up to 10,000 Pa) JI approaches under both “bubble cell” conditions (ambient pressure, 90°C) and also
under HP/HT conditions using specially designed autoclaves. The main aim was to enable high shear
measurements to be made under representative flow conditions and to study the effect of shear on
corrosion rates and corrosion inhibition for areas of the production system (such as ICD’s and ICV’s)
where significantly higher shear regimes exist. In conjunction with this, further developments have
been progressed to allow accurate electrochemical measurements to be made under JI conditions
allowing more rapid throughput of corrosion measurement, but more critically to obtain information on
the kinetic processes relating to corrosion and film formation / film persistence.
The results described in this paper illustrate therefore the developments made in the high shear JI and
LPT JI methodologies developed in our laboratories.
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For the techniques tested, LPR and weight loss data show good correlation in all test methods,
including the high shear JI approaches indicating that both electrochemical and weight loss methods
can be applied, providing increased confidence and validation of the accuracy of the electrochemical
measurements. This represents a significant benefit due to reduced test durations (typical LPR
measurements conducted over a 24 hour time frame compared with 7-28 days for long term weight loss
measurements).
The JI method appears to be more severe than RCE where equivalent maximum wall shear stresses are
examined. This is evidenced by the order of magnitude increase in corrosion rate at equivalent wall
shear stresses for L80-13Cr, the initially higher corrosion rates at equivalent wall shear stress for
C1018 (subsequently masked by corrosion product film formation), and the poorer CI performance on
C1018 under JI test conditions. The increased corrosion rates for the L80-13Cr is suspected to be due
to damage to the protective film caused by the fluid dynamics in the JI system whereas the lower
corrosion rates initially observed for the C1018 (at lower shears) appears to relate to increased
formation of protective carbonate surface films – which again may relate to the fluid dynamics. These
aspects are currently being investigated, although it is known from related works that surface scaling
can be exacerbated due to the fluid flow regimes within JI approaches [6].
In general the results conclude that although increased shear has a dramatic effect on surface corrosion,
the effect is non-linear and is also dependant on the materials. For C1018, maximum corrosion rates
plateau at relatively low shear (i.e. increasing surface shear from 200 to 10,000 Pa appears to result in
relatively minimal impact on the coverall corrosion rates). For other materials such as L80-13Cr
increasing the corrosion rate is still non-linear, but elevated corrosion rates are observed at higher
shears (e.g. ~ 0.15 mm/y at 400 Pa increasing to ~ 0.4 mm/y at 10,000 Pa) which is suspected to relate
to damage of the protective films. However, when examining corrosion inhibitor performance more
dramatic effects are recorded for the cases examined here, with reduced corrosion inhibitor
performance recorded at elevated shear. For conventional film forming corrosion inhibitors this is
expected, however understanding the corrosion inhibition and film persistency under very high shear
regimes remains of considerable interest. Further work is therefore ongoing examining inhibitor
performance at increased shear to determine the limits of different classes of film forming inhibitors.
Finally this work concludes that laboratory technique selection and an understanding of the flow
regimes in the field and laboratory is therefore of critical importance in selecting the test method most
applicable to a particular application. In rotating cylinder testing, it is the metal specimen that is
rotating at a constant rate relative to the test fluid, proving a uniform flow around the circumference of
the test metal, as would be experienced at moderate shears in pipeline flow. In jet impingement the
fluid flows through a nozzle and across the face of the test piece, making it more applicable to studies
of flow through orifices such as ICDs and ICVs and other very higher shear stresses experienced in and
around these devices. The differences recorded between different techniques can be explained both by
a combination of localised (surface) fluid flow dynamics and by the effect on surface film formation.
Further works are underway to simulate the fluid flow regimes under the different approaches and
compare these with a range of field conditions and is expected to be the subject of a forthcoming paper.
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References
1. Palmer, J., Hedges, W. and Dawson, J. eds. A Working Party Report on the Use of Corrosion
Inhibitors in Oil and Gas Production. Maney; published for the European Federation of
Corrosion on behalf of the Institute of Materials, Minerals and Mining. London, UK, 2004.
2. Kennely, K.J., Hausler, R.H., and Silverman, D.C., eds., Flow-Induced Corrosion:
Fundamental Studies and Industry Experience. NACE International, Houston, TX, USA,
1992.
3. ASTM G170-06, Standard Guide for Evaluating and Qualifying Oilfield and Refinery
Corrosion Inhibitors in the Laboratory. ASTM International, PA, USA.
4. Demoz, A., Dabros, T., Michaelian, K., Papavinasam, S., and Revie, W., A New Impinging Jet
Device for Corrosion Studies. Corrosion: May 2004, Vol. 60, No. 5, pp. 455-464.
5. ASTM G208-12, Standard Practise for Evaluating and Qualifying Oilfield and Refinery
Corrosion Inhibitors Using Jet Impingement Apparatus. ASTM International, PA, USA.
6. Graham, G. M., Thomson, H., Bowering, D. and Stalker, R., Correlation of Shear and
Turbulence on Scale Formation and Inhibition. SPE 169761 presented at the SPE
International Oilfield Scale Conference, Aberdeen, UK, 14-15 May 2014.
7. ASTM G1-03(2011), Standard Practice for Preparing, Cleaning, and Evaluating Corrosion
Test Specimens. ASTM International, PA, USA.
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