ASTM G202-12(2020)
(Test Method)Standard Test Method for Using Atmospheric Pressure Rotating Cage
Standard Test Method for Using Atmospheric Pressure Rotating Cage
SIGNIFICANCE AND USE
3.1 The rotating cage (RC) test system is relatively inexpensive and uses simple flat specimens that allow replicates to be run with each setup. (1-11).3
3.2 The RC method can be used to evaluate either corrosion inhibitors, or materials, or both. Practice G184 describes the procedure to use rotating cage to evaluate corrosion inhibitors.
3.3 In this test method, a general procedure is presented to obtain reproducible results using RC to simulate the effects of different types of coupon materials, inhibitor concentrations, oil, gas and brine compositions, temperature, and flow. Oil field fluids may often contain sand; however, this test method does not cover erosive effects that occur when sand is present.
SCOPE
1.1 This test method covers a generally accepted procedure to conduct the rotating cage (RC) experiment under atmospheric pressure.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: G202 − 12 (Reapproved 2020)
Standard Test Method for
Using Atmospheric Pressure Rotating Cage
This standard is issued under the fixed designation G202; 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 G46 Guide for Examination and Evaluation of Pitting Cor-
rosion
1.1 This test method covers a generally accepted procedure
G170 Guide for Evaluating and Qualifying Oilfield and
to conduct the rotating cage (RC) experiment under atmo-
Refinery Corrosion Inhibitors in the Laboratory
spheric pressure.
G184 Practice for Evaluating and Qualifying Oil Field and
1.2 The values stated in SI units are to be regarded as
Refinery Corrosion Inhibitors Using Rotating Cage
standard. The values given in parentheses after SI units are
provided for information only and are not considered standard.
3. Significance and Use
1.3 This standard does not purport to address all of the
3.1 The rotating cage (RC) test system is relatively inex-
safety concerns, if any, associated with its use. It is the
pensive and uses simple flat specimens that allow replicates to
responsibility of the user of this standard to establish appro-
be run with each setup. (1-11).
priate safety, health, and environmental practices and deter-
3.2 The RC method can be used to evaluate either corrosion
mine the applicability of regulatory limitations prior to use.
inhibitors, or materials, or both. Practice G184 describes the
1.4 This international standard was developed in accor-
procedure to use rotating cage to evaluate corrosion inhibitors.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 3.3 In this test method, a general procedure is presented to
Development of International Standards, Guides and Recom- obtain reproducible results using RC to simulate the effects of
mendations issued by the World Trade Organization Technical different types of coupon materials, inhibitor concentrations,
Barriers to Trade (TBT) Committee. oil,gasandbrinecompositions,temperature,andflow.Oilfield
fluids may often contain sand; however, this test method does
2. Referenced Documents
not cover erosive effects that occur when sand is present.
2.1 ASTM Standards:
4. Apparatus
D1141 Practice for the Preparation of Substitute Ocean
4.1 Fig. 1 shows the schematic diagram of the RC system.
Water
D1193 Specification for Reagent Water The vessel is manufactured from acrylic. At the bottom of the
container, a PTFE base is snugly fitted. At the center of the
D1293 Test Methods for pH of Water
E691 Practice for Conducting an Interlaboratory Study to base, a hole is drilled, into which the lower end of the rotating
shaft is placed. This arrangement stabilizes the rotating shaft
Determine the Precision of a Test Method
G1 Practice for Preparing, Cleaning, and Evaluating Corro- and the coupons. The length of the rotating shaft between the
sion Test Specimens top and bottom covers is 40 cm (15.7 in.). The rotating cage is
G16 Guide for Applying Statistics to Analysis of Corrosion attached to the shaft in such a way that the top of the cage is
Data 30 cm (11.8 in.) from the bottom cover.
G31 Guide for Laboratory Immersion Corrosion Testing of
4.2 Eight coupons (each of length 75 mm, width 19 mm,
Metals 2
thickness 3 mm, and surface area 34.14 cm )) are supported
betweentwoPTFEdisks(of80 mmdiameter)mounted75mm
apartonthestirringrod(Fig.2).Holes(diameter10mm)about
This test method is under the jurisdiction of ASTM Committee G01 on
15 mm away from the center are drilled in the top and bottom
Corrosion of Metals and is the direct responsibility of Subcommittee G01.05 on
PTFEplatesofthecagetoincreasetheturbulenceontheinside
Laboratory Corrosion Tests.
surface of the coupon (Fig. 3). This experimental setup can be
Current edition approved Nov. 1, 2020. Published November 2020. Originally
approved in 2009. Last previous edition approved in 2016 as G202 – 12 (2016).
used at rotation speeds up to 1000 rpm.
DOI: 10.1520/G0202-12R20.
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 boldface numbers in parentheses refer to a list of references at the end of
the ASTM website. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G202 − 12 (2020)
FIG. 1 Schematic Diagram of Rotating Cage
4.4 Volume of solution to the surface area of the specimen
has some effect on the corrosion rate. The minimum solution
3 2
volume(cm )tometalsurfacearea(cm )isnotlessthan14cm
3 2
(cm /cm ) (10).
5. Reagents
5.1 Purity of Reagents—Reagent-grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
all reagents conform to the specifications of the Committee on
Analytical Reagents of the American Chemical Society where
such specifications are available. Other grades may be used,
provided it is first ascertained that the reagent is of sufficiently
high purity to permit its use without lessening the accuracy of
the determination.
5.2 The composition of the solution shall be determined and
reported. Alternatively, standard brine (such as in Practice
D1141) shall be used. The solutions shall be prepared using
analytical grade reagents and deionized water (in accordance
with Specification D1193).
5.3 Thesolutionsshallbedeoxygenatedbypassingnitrogen
or any other inert gas for sufficient time to reduce the oxygen
NOTE 1—Gaps (typically 0.85 cm 6 0.01 cm) between the coupons
content below 5 ppb. The solution shall be kept under
introduce localized turbulence.
FIG. 2 Photo of Rotating Cage Containing Coupons
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
listed by the American Chemical Society, see Annual Standards for Laboratory
4.3 Flow patterns inside the RC depend on the rotation
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
speed, the volume of the container, and the nature of the fluids
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
used. The flow patterns are described in Guide G170. MD.
G202 − 12 (2020)
NOTE 1—Holes (typically 1.0 cm diameter, about 1.5 cm from the center) introduce localized turbulence
FIG. 3 Photo of Rotating Cage (Top View)
deoxygenated conditions. The oxygen concentration in solu- cally cleaned for 1 min, and dried. The surface of the
tion depends on the quality of gases used to purge the solution. specimens shall not be touched with bare hands. The speci-
Any leaks through the vessel, tubing, and joints shall be mens are weighed to the nearest 0.1 mg, the dimensions are
avoided. measured to the nearest 0.1 mm, and the surface areas are
calculated.
5.4 Warning—Hydrogen sulfide (H S) and carbon dioxide
(CO ) are corrosive gases. H S is poisonous and shall not be 6.4 Freshly prepared specimens are installed in the rotating
2 2
releasedtotheatmosphere.Theappropriatecompositionofgas cage holder. If the test is not commenced within 4 h, the
can be obtained by mixing H S and CO streams from the prepared coupons shall be stored in a desiccator to avoid
2 2
standard laboratory gas supply. Nitrogen can be used as a pre-rusting.
diluent to obtain the required composition of corrosive gases.
Alternatively,gasmixturesoftherequiredcompositionscanbe 7. Procedure
purchased from suppliers of industrial gases. The concentra-
7.1 A detailed procedure to determine corrosion rates from
tions of impurities, particularly oxygen, shall be kept below
mass loss is described in Guide G31.
5 ppb.
7.2 Solutions are prepared and presaturated with the experi-
5.5 The solution pH before and after testing shall be
mental gas mixture. If the solution is prepared in a separate
measured, recorded, and reported (in accordance with Test
container, it shall be transferred from the preparation vessel to
Methods D1293).
the experimental vessel under positive nitrogen pressure to
minimize air contamination during the transfer operation.
6. Test Specimens
7.3 The experiment shall be conducted at room temperature
6.1 Methodsforpreparingspecimensfortestsandremoving
(21 °C to 24 °C).
specimens after the test are described in Practice G1. Standard
7.4 The pre-weighed coupons and holder (described in 4.2)
laboratory glassware shall be used for weighing and measuring
reagent volumes. are inserted into the apparatus.
6.2 The coupon shall have the same metallographic struc- 7.5 The lid of the apparatus is sealed such that oxygen
ture as that used in the service components. The coupons shall cannot leak into the system through the lid.
be ground to a surface finish of 150 grit. The grinding shall
7.6 Initially all ports of the experimental vessel (Inlet 1,
produce a reproducible surface finish with no rust deposits,
Inlet2,andoutlet)areclosed.Anitrogengas(oranyotherinert
pits, or deep scratches.All sharp edges on the coupon shall be
gas) cylinder is hooked up to Inlet 2. The outlet is hooked to a
...
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