ASTM G184-06(2020)e1

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.
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Designation:G184 −06 (Reapproved 2020)
Standard Practice for
Evaluating and Qualifying Oil Field and Refinery Corrosion
Inhibitors Using Rotating Cage
This standard is issued under the fixed designation G184; 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.
ε NOTE—Replaced Terminology G15 with Terminology G193, and other editorial changes made throughout in Dec. 2020.
1. Scope High Pressure Environment, or Both
G170 Guide for Evaluating and Qualifying Oilfield and
1.1 This practice covers a generally accepted procedure to
Refinery Corrosion Inhibitors in the Laboratory
use the rotating cage (RC) for evaluating corrosion inhibitors
G193 Terminology and Acronyms Relating to Corrosion
for oil field and refinery applications.
D1141 Practice for the Preparation of Substitute Ocean
1.2 The values stated in SI units are to be regarded as
Water
standard. The values given in parentheses after SI units are
D4410 Terminology for Fluvial Sediment
provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the 3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 The terminology used throughout shall be in accordance
responsibility of the user of this standard to establish appro-
with Terminologies G193 and D4410 and Guide G170.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4. Summary of Practice
1.4 This international standard was developed in accor-
4.1 This practice provides a method of evaluating corrosion
dance with internationally recognized principles on standard-
inhibitor efficiency in a RC apparatus. The method uses a
ization established in the Decision on Principles for the
well-defined rotating specimen setup and mass loss measure-
Development of International Standards, Guides and Recom-
ments to determine corrosion rates in a laboratory apparatus.
mendations issued by the World Trade Organization Technical
Measurements are made at a number of rotation rates to
Barriers to Trade (TBT) Committee.
evaluate the inhibitor performance under increasingly severe
hydrodynamic conditions.
2. Referenced Documents
2.1 ASTM Standards:
5. Significance and Use
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
5.1 Selection of corrosion inhibitor for oil field and refinery
sion Test Specimens
applicationsinvolvesqualificationofcorrosioninhibitorsinthe
G16 Guide for Applying Statistics to Analysis of Corrosion
laboratory (see Guide G170). Field conditions should be
Data
simulated in the laboratory in a fast and cost-effective manner
G31 Guide for Laboratory Immersion Corrosion Testing of
(1).
Metals
5.2 Oil field corrosion inhibitors should provide protection
G46 Guide for Examination and Evaluation of Pitting Cor-
over a range of flow conditions from stagnant to that found
rosion
during typical production conditions. Not all inhibitors are
G111 Guide for Corrosion Tests in High Temperature or
equallyeffectiveoverthisrangeofconditionssoitisimportant
for a proper evaluation of inhibitors to test the inhibitors using
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion a range of flow conditions.
of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
5.3 The RC test system is relatively inexpensive and uses
Corrosion Tests.
Current edition approved Nov. 1, 2020. Published December 2020. Originally simple flat specimens that allow replicates to be run with each
approved in 2006. Last previous edition approved in 2016 as G184 – 06 (2016).
setup. (2-13).
DOI: 10.1520/G0184-06R20E01.
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 the 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
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G184−06 (2020)
5.4 In this practice, 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, pressure, and
flow. Oil field fluids may often contain sand; however, this
practice does not cover erosive effects that occur when sand is
present.
6. Apparatus
6.1 Fig. 1 shows the schematic diagram of the RC system.
An apparatus of suitable size (usually 7500 mL) is used,
consisting of inlet and outlet ports, thermowell, temperature-
regulating device, a heating device (mantle, hot plate, or bath),
and a specimen support system.
6.1.1 The vessel (typically 150 mm diameter) is manufac-
tured from an inert material. Cast acrylic and polytetrafluoro-
ethylene (PTFE) have been used.
6.1.2 A PTFE base is fitted at the bottom of the container.
At the center of the base, a hole is drilled into which the lower
end of a stirring rod is placed. This arrangement stabilizes the
stirrer and the coupons.
6.1.3 Typically, eight coupons (each of 75 mm length,
NOTE 1—Gaps (typically 0.85 cm 6 0.01 cm) between the coupons
19 mm width, and 3 mm thickness, and a surface area of about
introduce localized turbulence.
34.14 cm ) are supported between two PTFE disks (of 80 mm FIG. 2Photo of Rotating Cage Containing Coupons
diameter) mounted 75 mm apart on the stirring rod (Fig. 2).
Holes (10 mm diameter) about 15 mm away from the center
are drilled in the top and bottom PTFE plates of the cage to increase the turbulence on the inside surface of the coupon
FIG. 1Schematic Diagram of Rotating Cage
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G184−06 (2020)
(Fig. 3). This experimental setup can be used at temperatures 7.3 The coupons are rinsed with distilled water, degreased
up to 70 °C and rotation speeds up to 1000 rpm. by immersing in acetone (or any suitable alcohol), ultrasoni-
cally cleaned for 1 min, and dried. The surface of the
6.2 The flow pattern varies, depending on the rotation
specimens should not be touched with bare hands. The speci-
speed, the volume of the container, and the fluids. The flow
mens are weighed to the nearest 0.1 mg, the dimensions are
patterns are described in Guide G170.
measured to the nearest 0.1 mm, and the surface areas are
6.3 Volume of solution to the surface area of the specimen
calculated.
hassomeeffectonthecorrosionrateandhenceontheinhibitor
7.4 Freshly prepared specimens are installed in the rotating
efficiencies. The minimum solution volume to metal surface
cage holder. If the test is not commenced within 4 h, the
area is not less than 14 cm (11).
prepared coupons shall be stored in a desiccator to avoid
6.4 Open-beaker tests should not be used because of evapo-
pre-rusting.
ration and contamination. Open-beaker test must not be con-
ducted when H S (hydrogen sulfide) is used. In some tests,
8. Test Solutions
provisions might be needed for continuous flow or replenish-
ment of the corrosive liquid, while simultaneously maintaining 8.1 All solutions (oil and aqueous) should be obtained from
the field for which the inhibitor is being evaluated. These are
a controlled atmosphere.
known as live solutions. It is important that live solutions do
6.5 For experiments above atmospheric pressure, a high-
not already contain corrosion inhibitor. In the absence of live
temperature, high-pressure rotating cage (HTHPRC) system
solutions, synthetic solutions should be used, the composition
and a vessel that can withstand high pressure without leakage
of which should be based on field water analysis. The compo-
shall be used.
sition of the solution should be determined and reported.
6.6 The suggested components can be modified, simplified,
Alternatively, standard brine (such as in Practice D1141)
or made more sophisticated to fit the needs of a particular
should be employed. The solutions should be prepared using
investigation.
analytical grade reagents and deionized water.
8.2 The solutions should be deoxygenated by passing nitro-
7. Materials
gen or any other inert gas for sufficient time to reduce the
7.1 Methods for preparing specimens for tests and for
oxygen content below 5 ppb and preferably below 1 ppb in
removing specimens after the test are described in Practice G1.
solution. The solution must be kept under deoxygenated
Standardlaboratoryglasswareshouldbeusedforweighingand
conditions. The oxygen concentration in solution depends on
measuring reagent volumes.
the quality of gases used to purge the solution. Any leaks
7.2 The coupons shall be made of the material (such as through the vessel, tubing, and joints shall be avoided.
carbon steel) for which the inhibitor is being evaluated. The
8.3 The appropriate composition of gases is determined by
coupon should have the same metallographic structure as that
the composition of gases in the field for which the inhibitor is
usedintheservicecomponents.Thecouponsshouldbeground
evaluated. (Warning—Hydrogen sulfide (H S) and carbon
to a specified surface finish (such as 150 grit). The grinding
dioxide(CO )arecorrosivegases.)(Warning—H Sispoison-
2 2
should produce a reproducible surface finish, with no rust
ous and should not be released into the atmosphere.) The
deposits, pits, or deep scratches.All sharp edges on the coupon
appropriate composition of gas can be obtained by mixing H S
should be ground. All loose dirt particles should be removed.
and CO streams from the standard laboratory gas supply.
Nitrogen or other inert gases can be used as a diluent to obtain
the required composition of corrosive gases.Alternatively, gas
mixtures of the required compositions can be purchased from
suppliers of industrial gases. The concentrations of impurities,
particularly oxygen, shall be kept as low as possible with
guidelines of below 5 ppb and preferably under 1 ppb oxygen
in solution.
8.4 The solution pH before and after testing shall be
measured, recorded and reported. The solution pH should be
monitored regularly (at least once a day) during the test.
8.5 Inhibitor concentrations should be measured and re-
ported in % mass/volume or parts per million (ppm). The
method of injecting the inhibitor into the test solution should
reflect the actual field application. Water-soluble inhibitors
may be injected neat (as-received) into the test solution
(aqueous phase). To avoid the errors associated with handling
small volumes of solution, an inhibitor stock solution may be
NOTE 1—Holes (typically 1.0 cm in diameter, and about 1.5 cm from
preparedbydilutingtheas-receivedchemicalinanappropriate
the center) introduce localized turbulence.
FIG. 3Photo of Rotating Cage (Top View) solvent. The type of solvent and the concentration of the stock
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G184−06 (2020)
solution depend on the characteristics of the inhibitor and on 9.7 After 15 min, stop the gas flow, and close the passage
the specified test conditions. between the experimental vessel and the gas cylinder.
9.8 Open the passage between the experimental and prepa-
8.6 Oil-soluble, water-dispersible inhibitor solutions are
ration vessels, and pump the gas-saturated brine, which may or
prepared by the following partition method. The required
may not contain inhibitor prepared as per 8.4 or 8.5, into the
amounts of oil and brine are placed in the partitioning vessel
experimental vessel.
(usually a separation funnel). The relative volumes of oil and
aqueous phases should reflect the ratios of water and oil in the
9.9 Close the passage between the experimental and prepa-
field for which the inhibitor is evaluated. If samples from the
rationvessels.Maintaintheexperimentalvesselwiththeheater
field are not available, heptane, kerosine, or any suitable
or the water bath at the required temperature.
hydrocarbon may be used. The corrosion inhibitor is added to
9.10 The additional gas inlet on top of the vessel should
the oil phase. The vessel is vigorously shaken for 1 min to mix
all
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