ASTM G208-12(2016)
(Practice)Standard Practice for Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors Using Jet Impingement Apparatus
Standard Practice for Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors Using Jet Impingement Apparatus
SIGNIFICANCE AND USE
5.1 Selection of corrosion inhibitor for oilfield and refinery applications involves qualification of corrosion inhibitors in the laboratory (see Guide G170). Field conditions should be simulated in the laboratory in a fast and cost-effective manner.
5.2 Oilfield and refinery corrosion inhibitors should provide protection over a range of flow conditions from stagnant to that found during typical production conditions. The inhibitors are not equally effective over all flow conditions, so it is important to determine the flow conditions in which they are effective.
5.3 Severity of hydrodynamic conditions depends on the type of laboratory methodology. Typically, rotating cylinder electrode is effective up to 20 Pa of wall shear stress, rotating cage (RC) is effective between 20 and 200 Pa of wall shear stress, and jet impingement (JI) is effective at wall shear stress above 200 Pa (1)3 of wall shear stress.
5.4 The JI test system is relatively inexpensive and uses simple flat specimens.
5.5 In this practice, a general procedure is presented to obtain reproducible results using JI simulating the effects of different types of coupon materials; inhibitor concentrations; oil, gas, and brine compositions; temperature; pressure; and flow. Erosive effects predominate when the flow rate is very high (typically above 500 Pa) or when sand or solid particles are present; however, this practice does not cover the erosive effects.
SCOPE
1.1 This practice covers a generally accepted procedure to use the jet impingement (JI) apparatus for evaluating corrosion inhibitors for oilfield and refinery applications in defined flow conditions.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:G208 −12 (Reapproved 2016)
Standard Practice for
Evaluating and Qualifying Oilfield and Refinery Corrosion
Inhibitors Using Jet Impingement Apparatus
This standard is issued under the fixed designation G208; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope G31 Guide for Laboratory Immersion Corrosion Testing of
Metals
1.1 This practice covers a generally accepted procedure to
G46 Guide for Examination and Evaluation of Pitting Cor-
use the jet impingement (JI) apparatus for evaluating corrosion
rosion
inhibitors for oilfield and refinery applications in defined flow
G59 Test Method for Conducting Potentiodynamic Polariza-
conditions.
tion Resistance Measurements
1.2 The values stated in SI units are to be regarded as
G96 Guide for Online Monitoring of Corrosion in Plant
standard. No other units of measurement are included in this
Equipment (Electrical and Electrochemical Methods)
standard.
G102 Practice for Calculation of Corrosion Rates and Re-
1.3 This standard does not purport to address all of the lated Information from Electrochemical Measurements
safety concerns, if any, associated with its use. It is the
G106 Practice for Verification of Algorithm and Equipment
responsibility of the user of this standard to establish appro- for Electrochemical Impedance Measurements
priate safety and health practices and determine the applica-
G111 Guide for Corrosion Tests in High Temperature or
bility of regulatory limitations prior to use. High Pressure Environment, or Both
G170 Guide for Evaluating and Qualifying Oilfield and
2. Referenced Documents
Refinery Corrosion Inhibitors in the Laboratory
2.1 ASTM Standards:
G184 Practice for Evaluating and Qualifying Oil Field and
D1141 Practice for the Preparation of Substitute Ocean Refinery Corrosion Inhibitors Using Rotating Cage
Water
G185 Practice for Evaluating and Qualifying Oil Field and
D1193 Specification for Reagent Water
RefineryCorrosionInhibitorsUsingtheRotatingCylinder
D4410 Terminology for Fluvial Sediment Electrode
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
G193 Terminology and Acronyms Relating to Corrosion
sion Test Specimens
3. Terminology
G5 Reference Test Method for Making Potentiodynamic
Anodic Polarization Measurements
3.1 Theterminologyusedhereinshallbeinaccordancewith
G16 Guide for Applying Statistics to Analysis of Corrosion
Terminology D4410, Guide G170, and Terminology G193.
Data
4. Summary of Practice
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion 4.1 Thispracticeprovidesamethodforevaluatingcorrosion
of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
inhibitor efficiency in jet impingement (JI) apparatus. The
Corrosion Tests.
method uses a well-defined impinging jet set up and mass loss
Current edition approved Nov. 1, 2016. Published November 2016. Originally
or electrochemical techniques to measure corrosion rates.
approved in 2012. Last previous edition approved in 2012 as G208 – 12. DOI:
10.1520/G0208-12R16.
Measurements are made using three different experimental
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
designs and at several flow rates to evaluate the inhibitor
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
performance under increasingly severe hydrodynamic condi-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tions.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G208−12 (2016)
5. Significance and Use flow. Erosive effects predominate when the flow rate is very
high (typically above 500 Pa) or when sand or solid particles
5.1 Selection of corrosion inhibitor for oilfield and refinery
are present; however, this practice does not cover the erosive
applicationsinvolvesqualificationofcorrosioninhibitorsinthe
effects.
laboratory (see Guide G170). Field conditions should be
simulated in the laboratory in a fast and cost-effective manner.
6. Apparatus
5.2 Oilfield and refinery corrosion inhibitors should provide
6.1 The actual hydrodynamic conditions in the tests must be
protectionoverarangeofflowconditionsfromstagnanttothat
known to enable comparison of results with those obtained in
found during typical production conditions. The inhibitors are
other tests or predictions of inhibitor performance in practical
not equally effective over all flow conditions, so it is important
operating systems. Hydrodynamic parameters in jet impinge-
to determine the flow conditions in which they are effective.
ment are described in Annex A1. These hydrodynamic rela-
5.3 Severity of hydrodynamic conditions depends on the
tionships are valid only for a specific range and are influenced
type of laboratory methodology. Typically, rotating cylinder
by the geometry and orientation of specimen and apparatus.A
electrode is effective up to 20 Pa of wall shear stress, rotating
minor change in any one parameter drastically alters the
cage (RC) is effective between 20 and 200 Pa of wall shear
hydrodynamic parameters.
stress, and jet impingement (JI) is effective at wall shear stress
6.2 A proper experimental design must consider the jet
above 200 Pa (1) of wall shear stress.
velocity, radial distance, radius of the electrode (ring or disc),
5.4 The JI test system is relatively inexpensive and uses
distance between jet nozzle and the electrode, and jet nozzle
simple flat specimens.
diameter. Some typical parameters for describing jet impinge-
5.5 In this practice, a general procedure is presented to mentapparatusarelistedinTable1.Agoodlaboratorypractice
obtain reproducible results using JI simulating the effects of
would be to control, record, and report all the system specifi-
different types of coupon materials; inhibitor concentrations; cations.
oil, gas, and brine compositions; temperature; pressure; and
6.3 Depending on the geometry of apparatus and size and
shape of the specimens there are three jet impingement
apparatus designs.
The boldface numbers in parentheses refer to a list of references at the end of
6.3.1 Design 1:
this standard.
TABLE 1 Parameters to be Reported Along with Test Results
Parameter Units Remarks
Solution chemistry
Material chemistry
Solution density
Solution viscosity
Temperature C or F or K
Pressure psi or kPa For elevated pressure experiments
Jet velocity m/s or cm/s or inch/s
Specimen type ring or disc
Disc diameter mm or cm or m For disc electrodes only
ring diameter (inner) mm or cm or m For ring electrodes only
ring diameter (outer) mm or cm or m For ring electrodes only
radial distance mm or cm or m
Distance between jet and the nozzle mm or cm or m
Rotation speed RPM
Electrode diameter or radius mm or cm or m
Volume of container cm
Volume of solution cm
Tafel constants, anodic, cathodic For electrochemical measurements
Description of counter electrode (size, shape, and For electrochemical measurements
distance from the working electrode)
Initial mass mg or g For mass loss measurements
Final mass mg or g For mass loss measurements
Corrosion rate in absence of inhibitor mpy or mm/yr
Inhibitor efficiency, at each inhibitor concentration %
Number of specimens
Volume of solution/surface area of the electrode cm
Inhibitor type continuous or batch
Inhibitor concentration ppm or vol/vol or mass/volume or mass/mass
Description of EIS model Provide the model and elements (for electrochemical
measurements)
Solution conductivity Siemens For electrochemical measurements
Presence of oil yes or no
If oil is present, volume of oil cm
Duration of experiments Minutes, hour, day
Type of reference electrode For electrochemical measurements
Number of specimens
G208−12 (2016)
6.3.1.1 In this design, the working electrode is a disc and is are within the jet region. Typical distance between the jet
exposed only to the stagnation region (Fig. 1)(2-4). Typical nozzle tip and the specimen is 0.4 cm (that is, two times the
diameter of the jet nozzle is 0.6 cm and is placed axis- diameter of the jet).
symmetric to the specimen (working electrode). The diameter 6.3.2.2 The jet nozzle is manufactured using a nonmetallic
of the specimen is equal to or less than the diameter of the jet cylinder (typically of 1.25 cm of outer diameter with a 0.2 cm
nozzle. The typical distance between the jet nozzle tip and inletholeinthecenter).Thelengthofthecylinder(typically20
specimen is 3 cm (that is, five times the diameter of the jet cm) is long enough so that the fluid flow stabilizes before
nozzle). exiting through the nozzle. The counter electrode is placed at
6.3.1.2 The jet system is a submerged type and it impinges the end of the jet nozzle (Fig. 5). The reference electrode is
at 90° onto the specimen. Both the counter electrode and the placed adjacent to the counter electrode.
reference electrode are placed adjacent to the nozzle, so that 6.3.3 Design 3:
they are not in the path of the jet impinging on the working 6.3.3.1 In this design, the specimen is a disc and is exposed
electrode (Fig. 2). to all three regions of jet (stagnant, jet, and hydrodynamic
6.3.2 Design 2: regions) (see Fig. 6). This design facilitates occurrence of
6.3.2.1 In this design, the specimen is a ring and is exposed localized corrosion as the specimen is under the influence of
only to the jet region (Fig. 3 and Fig. 4) (5, 6).The diameter of various regions (stagnation, wall jet, and hydrodynamic re-
the jet nozzle is 0.2 cm. The diameter of the specimen is three gions).
times the diameter of the jet nozzle (measured to the centerline 6.3.3.2 The diameter of the jet nozzle is 0.64 cm. The
ofthering).Theinnerandouterdiametersoftheringspecimen diameter of the specimen is five times the diameter of the jet
NOTE 1—r/r is less than 2 (D is the diameter of the jet, r is the radius of the jet, r is the radius of the specimen, and H is the distance between
jet jet jet
the jet tip and the specimen surface). Shaded area indicates the location of the specimen.
FIG. 1Schematic Diagram (Side View) of Impinging Jet on a Specimen in Stagnation Region
G208−12 (2016)
NOTE 1—Figure not to scale. Shaded area indicates the location of the specimen.
FIG. 2Schematic Diagram of Experimental Test Cell (Design 1)
nozzle. Typical distance between the jet nozzle tip and the 6.6 For all designs, the apparatus must contain ports for
specimen is 3.2 cm (that is, five times the diameter of the jet) specimen, counter electrode, reference electrode, inlet and
(7, 8). outlet. Additional ports enable measurement of pH and tem-
perature during the experiment and draining of the test solution
NOTE 1—The larger size of the specimen may also enable it to be used
aftertheexperiment.Bothinletandoutletportsshouldbefitted
as a mass loss coupon.
with a Y joint, so that the apparatus is connected to both a gas
6.3.3.3 The counter electrode is placed on the return path of
cylinder and the preparation apparatus. In Design 1 and 2, a
the jet to avoid interference with the jet flow (Fig. 7).
pump that creates the jet should be placed between the
Reference electrode is placed in the side of the jet arm.
preparation and experimental apparatus. In Design 3, the pump
6.3.3.4 This design uses multiple specimens (typically four)
should be placed inside the apparatus itself.
(Fig. 8). The jet is created in a central cell with four arms
6.7 The suggested components can be modified, simplified,
containingfournozzles.Theimpellerishousedinthecellbody
or made more sophisticated to fit the needs of a particular
and is driven by a motor magnetically coupled to the impeller
investigation. The suggested apparatus is basic and the appa-
shaft. Fluid from the cell is forced by the impeller through the
ratus is limited only by the judgment and ingenuity of the
nozzles and is recirculated to the cell. All moving parts of the
investigator.
pump are located inside the central cell (7).
6.4 For all designs, the relationship between the motor
7. Preparation of Test Specimens
speed that creates the jet and the flow rate shall be established.
A procedure to establish such a relationship is described in 7.1 Methods for preparing specimens for tests and for
removing specimens after the test are described in Practice G1.
Annex A2.
6.5 For atmospheric pressure experiment, an apparatus con- 7.2 The specimen shall be made of the material (for
structed from acrylic, PFTE, or an inert material shall be used. example, carbon steel) for which the inhibitor is being evalu-
For experiments above atmospheric pressure, an apparatus that ated. Corrosion rates and inhibitor performance change by
can withstand high pressure without leakage must be used. severalordersofmagnitudeassurfaceroughnesschangesfrom
Such high-temperature, high-pressure jet impingement (HTH- rough to fine. The surface roughness shall be kept the same
PJI) system is constructed using corrosion-resistant alloy during inhibitor screening and, if possible, the surface rough-
(CRA). ness of specimens used in the laboratory experiments shall be
G208−12 (2016)
NOTE 1—(r is the radius of jet, D is the diameter of jet nozzle, and H is the distance between jet nozzle and the specimen). Shaded area indicates
jet jet
the location of the specimen.
FIG. 3Schematic Diagram (Side View) of Impinging Jet on a Specimen in Wall Jet Region
related to that of field pipe. The specimens shall be ground to suitable solvent; ultrasonically cleaned (typically for about 1
a specified surface finish. The grinding shall produce a repro- min); and then dried by blowing air. The surface of the
ducible surface finish, with no rust deposits, pits, or deep specimens shall not be touched with bare hands. The specimen
scratches.All sharp edges on the specimen shall be ground.All shallbeweighedtothenearest0.1mg.Thedimensionsshallbe
loose dirt particles shall be removed. measured to the nearest 1 mm and the surface area calculated.
7.3 Theappropriateringordiscspecimenshallbemachined 7.5 The specimen shall be placed into the experimental
andsnuglyfittedintothePTFEsampleholderorsampleholder apparatus within 1 h of preparing the surface and the lid of the
made from any other appropriate material, with no gap apparatus closed immediately.
between the sample and the holder. If necessary, a very small 7.5.1 Specimen to be treated with batch inhibitor shall be
amount of epoxy shou
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: G208 − 12 G208 − 12 (Reapproved 2016)
Standard Practice for
Evaluating and Qualifying Oilfield and Refinery Corrosion
Inhibitors Using Jet Impingement Apparatus
This standard is issued under the fixed designation G208; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers a generally accepted procedure to use the jet impingement (JI) apparatus for evaluating corrosion
inhibitors for oilfield and refinery applications in defined flow conditions.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D1141 Practice for the Preparation of Substitute Ocean Water
D1193 Specification for Reagent Water
D4410 Terminology for Fluvial Sediment
G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
G5 Reference Test Method for Making Potentiodynamic Anodic Polarization Measurements
G16 Guide for Applying Statistics to Analysis of Corrosion Data
G31 Guide for Laboratory Immersion Corrosion Testing of Metals
G46 Guide for Examination and Evaluation of Pitting Corrosion
G59 Test Method for Conducting Potentiodynamic Polarization Resistance Measurements
G96 Guide for Online Monitoring of Corrosion in Plant Equipment (Electrical and Electrochemical Methods)
G102 Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements
G106 Practice for Verification of Algorithm and Equipment for Electrochemical Impedance Measurements
G111 Guide for Corrosion Tests in High Temperature or High Pressure Environment, or Both
G170 Guide for Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors in the Laboratory
G184 Practice for Evaluating and Qualifying Oil Field and Refinery Corrosion Inhibitors Using Rotating Cage
G185 Practice for Evaluating and Qualifying Oil Field and Refinery Corrosion Inhibitors Using the Rotating Cylinder Electrode
G193 Terminology and Acronyms Relating to Corrosion
3. Terminology
3.1 The terminology used herein shall be in accordance with Terminology D4410, Guide G170, and Terminology G193.
4. Summary of Practice
4.1 This practice provides a method for evaluating corrosion inhibitor efficiency in jet impingement (JI) apparatus. The method
uses a well-defined impinging jet set up and mass loss or electrochemical techniques to measure corrosion rates. Measurements
are made using three different experimental designs and at several flow rates to evaluate the inhibitor performance under
increasingly severe hydrodynamic conditions.
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory Corrosion
Tests.
Current edition approved May 1, 2012Nov. 1, 2016. Published December 2012November 2016. Originally approved in 2012. Last previous edition approved in 2012 as
G208 – 12. DOI: 10.1520/G0208–12.10.1520/G0208-12R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G208 − 12 (2016)
5. Significance and Use
5.1 Selection of corrosion inhibitor for oilfield and refinery applications involves qualification of corrosion inhibitors in the
laboratory (see Guide G170). Field conditions should be simulated in the laboratory in a fast and cost-effective manner.
5.2 Oilfield and refinery corrosion inhibitors should provide protection over a range of flow conditions from stagnant to that
found during typical production conditions. The inhibitors are not equally effective over all flow conditions, so it is important to
determine the flow conditions in which they are effective.
5.3 Severity of hydrodynamic conditions depends on the type of laboratory methodology. Typically, rotating cylinder electrode
is effective up to 20 Pa of wall shear stress, rotating cage (RC) is effective between 20 and 200 Pa of wall shear stress, and jet
impingement (JI) is effective at wall shear stress above 200 Pa (1) of wall shear stress.
5.4 The JI test system is relatively inexpensive and uses simple flat specimens.
5.5 In this practice, a general procedure is presented to obtain reproducible results using JI simulating the effects of different
types of coupon materials; inhibitor concentrations; oil, gas, and brine compositions; temperature; pressure; and flow. Erosive
effects predominate when the flow rate is very high (typically above 500 Pa) or when sand or solid particles are present; however,
this practice does not cover the erosive effects.
6. Apparatus
6.1 The actual hydrodynamic conditions in the tests must be known to enable comparison of results with those obtained in other
tests or predictions of inhibitor performance in practical operating systems. Hydrodynamic parameters in jet impingement are
described in Annex A1. These hydrodynamic relationships are valid only for a specific range and are influenced by the geometry
and orientation of specimen and apparatus. A minor change in any one parameter drastically alters the hydrodynamic parameters.
6.2 A proper experimental design must consider the jet velocity, radial distance, radius of the electrode (ring or disc), distance
between jet nozzle and the electrode, and jet nozzle diameter. Some typical parameters for describing jet impingement apparatus
are listed in Table 1. A good laboratory practice would be to control, record, and report all the system specifications.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
TABLE 1 Parameters to be Reported Along with Test Results
Parameter Units Remarks
Solution chemistry
Material chemistry
Solution density
Solution viscosity
Temperature C or F or K
Pressure psi or kPa For elevated pressure experiments
Jet velocity m/s or cm/s or inch/s
Specimen type ring or disc
Disc diameter mm or cm or m For disc electrodes only
ring diameter (inner) mm or cm or m For ring electrodes only
ring diameter (outer) mm or cm or m For ring electrodes only
radial distance mm or cm or m
Distance between jet and the nozzle mm or cm or m
Rotation speed RPM
Electrode diameter or radius mm or cm or m
Volume of container cm
Volume of solution cm
Tafel constants, anodic, cathodic For electrochemical measurements
Description of counter electrode (size, shape, and For electrochemical measurements
distance from the working electrode)
Initial mass mg or g For mass loss measurements
Final mass mg or g For mass loss measurements
Corrosion rate in absence of inhibitor mpy or mm/yr
Inhibitor efficiency, at each inhibitor concentration %
Number of specimens
Volume of solution/surface area of the electrode cm
Inhibitor type continuous or batch
Inhibitor concentration ppm or vol/vol or mass/volume or mass/mass
Description of EIS model Provide the model and elements (for electrochemical
measurements)
Solution conductivity Siemens For electrochemical measurements
Presence of oil yes or no
If oil is present, volume of oil cm
Duration of experiments Minutes, hour, day
Type of reference electrode For electrochemical measurements
Number of specimens
G208 − 12 (2016)
6.3 Depending on the geometry of apparatus and size and shape of the specimens there are three jet impingement apparatus
designs.
6.3.1 Design 1:
6.3.1.1 In this design, the working electrode is a disc and is exposed only to the stagnation region (Fig. 1) (2-4). Typical diameter
of the jet nozzle is 0.6 cm and is placed axis-symmetric to the specimen (working electrode). The diameter of the specimen is equal
to or less than the diameter of the jet nozzle. The typical distance between the jet nozzle tip and specimen is 3 cm (that is, five
times the diameter of the jet nozzle).
6.3.1.2 The jet system is a submerged type and it impinges at 90° onto the specimen. Both the counter electrode and the
reference electrode are placed adjacent to the nozzle, so that they are not in the path of the jet impinging on the working electrode
(Fig. 2).
6.3.2 Design 2:
6.3.2.1 In this design, the specimen is a ring and is exposed only to the jet region (Fig. 3 and Fig. 4) (5, 6). The diameter of
the jet nozzle is 0.2 cm. The diameter of the specimen is three times the diameter of the jet nozzle (measured to the centerline of
the ring). The inner and outer diameters of the ring specimen are within the jet region. Typical distance between the jet nozzle tip
and the specimen is 0.4 cm (that is, two times the diameter of the jet).
6.3.2.2 The jet nozzle is manufactured using a nonmetallic cylinder (typically of 1.25 cm of outer diameter with a 0.2 cm inlet
hole in the center). The length of the cylinder (typically 20 cm) is long enough so that the fluid flow stabilizes before exiting
through the nozzle. The counter electrode is placed at the end of the jet nozzle (Fig. 5). The reference electrode is placed adjacent
to the counter electrode.
NOTE 1—r/r is less than 2 (D is the diameter of the jet, r is the radius of the jet, r is the radius of the specimen, and H is the distance between
jet jet jet
the jet tip and the specimen surface). Shaded area indicates the location of the specimen.
FIG. 1 Schematic Diagram (Side View) of Impinging Jet on a Specimen in Stagnation Region
G208 − 12 (2016)
NOTE 1—Figure not to scale. Shaded area indicates the location of the specimen.
FIG. 2 Schematic Diagram of Experimental Test Cell (Design 1)
6.3.3 Design 3:
6.3.3.1 In this design, the specimen is a disc and is exposed to all three regions of jet (stagnant, jet, and hydrodynamic regions)
(see Fig. 6). This design facilitates occurrence of localized corrosion as the specimen is under the influence of various regions
(stagnation, wall jet, and hydrodynamic regions).
6.3.3.2 The diameter of the jet nozzle is 0.64 cm. The diameter of the specimen is five times the diameter of the jet nozzle.
Typical distance between the jet nozzle tip and the specimen is 3.2 cm (that is, five times the diameter of the jet) (7, 8).
NOTE 1—The larger size of the specimen may also enable it to be used as a mass loss coupon.
6.3.3.3 The counter electrode is placed on the return path of the jet to avoid interference with the jet flow (Fig. 7). Reference
electrode is placed in the side of the jet arm.
6.3.3.4 This design uses multiple specimens (typically four) (Fig. 8). The jet is created in a central cell with four arms containing
four nozzles. The impeller is housed in the cell body and is driven by a motor magnetically coupled to the impeller shaft. Fluid
from the cell is forced by the impeller through the nozzles and is recirculated to the cell. All moving parts of the pump are located
inside the central cell (7).
6.4 For all designs, the relationship between the motor speed that creates the jet and the flow rate shall be established. A
procedure to establish such a relationship is described in Annex A2.
6.5 For atmospheric pressure experiment, an apparatus constructed from acrylic, PFTE, or an inert material shall be used. For
experiments above atmospheric pressure, an apparatus that can withstand high pressure without leakage must be used. Such
high-temperature, high-pressure jet impingement (HTHPJI) system is constructed using corrosion-resistant alloy (CRA).
6.6 For all designs, the apparatus must contain ports for specimen, counter electrode, reference electrode, inlet and outlet.
Additional ports enable measurement of pH and temperature during the experiment and draining of the test solution after the
experiment. Both inlet and outlet ports should be fitted with a Y joint, so that the apparatus is connected to both a gas cylinder
and the preparation apparatus. In Design 1 and 2, a pump that creates the jet should be placed between the preparation and
experimental apparatus. In Design 3, the pump should be placed inside the apparatus itself.
6.7 The suggested components can be modified, simplified, or made more sophisticated to fit the needs of a particular
investigation. The suggested apparatus is basic and the apparatus is limited only by the judgment and ingenuity of the investigator.
G208 − 12 (2016)
NOTE 1—(r is the radius of jet, D is the diameter of jet nozzle, and H is the distance between jet nozzle and the specimen). Shaded area indicates
jet jet
the location of the specimen.
FIG. 3 Schematic Diagram (Side View) of Impinging Jet on a Specimen in Wall Jet Region
7. Preparation of Test Specimens
7.1 Methods for preparing specimens for tests and for removing specimens after the test are described in Practice G1.
7.2 The specimen shall be made of the material (for example, carbon steel) for which the inhibitor is being evaluated. Corrosion
rates and inhibitor performance change by several orders of magnitude as surface roughness changes from rough to fine. The
surface roughness shall be kept the same during inhibitor screening and, if possible, the surface roughness of specimens used in
the laboratory experiments shall be related to that of field pipe. The specimens shall be ground to a specified surface finish. The
grinding shall produce a reproducible surface finish, with no rust deposits, pits, or deep scratches. All sharp edges on the specimen
shall be ground. All loose dirt particles shall be removed.
7.3 The appropriate ring or disc specimen shall be machined and snugly fitted into the PTFE sample holder or sample holder
made from any other appropriate material, with no gap between the sample and the holder. If necessary, a very small amount of
epoxy should be used to fit the specimen into the holder. The presence of a gap will create
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.