ASTM G97-97(2007)
(Test Method)Standard Test Method for Laboratory Evaluation of Magnesium Sacrificial Anode Test Specimens for Underground Applications
Standard Test Method for Laboratory Evaluation of Magnesium Sacrificial Anode Test Specimens for Underground Applications
SIGNIFICANCE AND USE
This test is a guide for evaluating magnesium anodes. The degree of correlation between this test and service performance has not been fully determined.
SCOPE
1.1 This test method covers a laboratory procedure that measures the two fundamental performance properties of magnesium sacrificial anode test specimens operating in a saturated calcium sulfate, saturated magnesium hydroxide environment. The two fundamental properties are electrode (oxidation potential) and ampere hours (Ah) obtained per unit mass of specimen consumed. Magnesium anodes installed underground are usually surrounded by a backfill material that typically consists of 75 % gypsum (CaSO4·2H2O), 20 % bentonite clay, and 5 % sodium sulfate (Na2SO4). The calcium sulfate, magnesium hydroxide test electrolyte simulates the long term environment around an anode installed in the gypsum-bentonite-sodium sulfate backfill.
1.2 This test method is intended to be used for quality assurance by anode manufacturers or anode users. However, long term field performance properties may not be identical to property measurements obtained using this laboratory test.
Note 1—Refer to Terminology G 15 for terms used in this test method.
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. For specific precautions, See Section 7 and Paragraph 8.1.1.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:G97 −97(Reapproved 2007)
Standard Test Method for
Laboratory Evaluation of Magnesium Sacrificial Anode Test
Specimens for Underground Applications
This standard is issued under the fixed designation G97; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope G15 Terminology Relating to Corrosion and Corrosion Test-
ing (Withdrawn 2010)
1.1 This test method covers a laboratory procedure that
G16 Guide for Applying Statistics to Analysis of Corrosion
measures the two fundamental performance properties of
Data
magnesium sacrificial anode test specimens operating in a
2.2 American National Standard:
saturated calcium sulfate, saturated magnesium hydroxide
ANSI/NFPA 480 Storage, Handling, and Processing of
environment. The two fundamental properties are electrode
Magnesium, 1987 Edition
(oxidation potential) and ampere hours (Ah) obtained per unit
mass of specimen consumed. Magnesium anodes installed
3. Summary of Test Method
underground are usually surrounded by a backfill material that
typically consists of 75 % gypsum (CaSO ·2H O), 20 % ben- 3.1 A known direct current is passed through test cells
4 2
tonite clay, and 5 % sodium sulfate (Na SO ). The calcium connected in series. Each test cell consists of a pre-weighed
2 4
sulfate, magnesium hydroxide test electrolyte simulates the test magnesium alloy anode specimen, a steel pot container
long term environment around an anode installed in the cathode, and a known electrolyte. Test specimen oxidation
gypsum-bentonite-sodium sulfate backfill. potential is measured several times during the 14-day test and
1 h after the current is turned off at the end of the test.The total
1.2 This test method is intended to be used for quality
Ah passed through the cells are measured.At the conclusion of
assurance by anode manufacturers or anode users. However,
the test, each test specimen is cleaned and weighed. The Ah
long term field performance properties may not be identical to
obtained per unit mass of specimen lost is calculated.
property measurements obtained using this laboratory test.
NOTE 1—Refer to Terminology G15 for terms used in this test method. 4. Significance and Use
1.3 This standard does not purport to address all of the
4.1 This test is a guide for evaluating magnesium anodes.
safety concerns, if any, associated with its use. It is the
The degree of correlation between this test and service perfor-
responsibility of the user of this standard to establish appro-
mance has not been fully determined.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. For specific
5. Apparatus
precautions, See Section 7 and Paragraph 8.1.1.
5.1 The basic test equipment consists of the following:
5.1.1 Direct Current Power Source, (optional), capable of
2. Referenced Documents
delivering at least 2 mA and 12 V.
2.1 ASTM Standards:
5.1.2 Steel Cathode Test Pot, as shown in Fig. 1.
D1193 Specification for Reagent Water
5.1.3 Copper Coulometer, as shown in Fig. 2,or Electronic
G3 Practice for Conventions Applicable to Electrochemical
Coulometer.
Measurements in Corrosion Testing
5.1.4 Saturated Calomel Reference Electrode.
5.1.5 Electrometer, with an input impedance of 10 or
greater ohms.
5.1.6 Balance, 100-g capacity with 0.1 mg sensitivity.
This test method is under the jurisdiction of ASTM Committee G01 on
Corrosion of Metals and is the direct responsibility of Subcommittee G01.10 on
5.1.7 Drying Oven, with temperature capability of 110°C or
Corrosion in Soils.
higher.
Current edition approved Nov. 1, 2007. Published January 2008. Originally
´1
approved in 1989. Last previous edition approved in 2002 as G97–(2002) . DOI:
10.1520/G0097-97R07.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on Available from National Fire Protection Association (NFPA), 1 Batterymarch
the ASTM website. Park, Quincy, MA 02169-7471, http://www.nfpa.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G97−97 (2007)
cleaning solution. Test specimen cleaning should be done in a
ventilated laboratory hood.
7.2 Local, state, and federal regulations should be complied
with in disposing of used cleaning solution.
8. Specimen Preparation
8.1 Fig. 3 shows typical test specimen selection and prepa-
ration from a cast anode. Since all sizes and shapes of cast
anodes are not shown, the sampling is only illustrative. Test
specimens are obtained across the width of a cast anode and
approximately 13 mm from the edge. Machine each test
specimen from a sawed, 180-mm long, 16-mm square cross
section portion of the cast anode. Dry machine the square cross
section, which should be marked with a stamped identification
number, down to 12.7-mm diameter using a machining speed
of 800 r/min, a feed rate of 0.5 mm per revolution, and a depth
of cut of 1.9 mm or less. Cut the machined test specimen to a
152-mm length and machine-face one end.
8.1.1 Magnesium fines produced during cutting and ma-
chining operations can present a fire hazard. ANSI/NFPA 480
should be consulted for procedures for handling magnesium.
8.1.2 Band saws and power hacksaws with the following
characteristics are recommended for use on magnesium:
8.1.2.1 Blade pitch (teeth/cm)—Band saw = 1.6 to 2.4,
power hacksaw = 0.8 to 2.4.
FIG. 1 Detail of Test Pot
FIG. 2 Copper Coulometer
6. Reagents
6.1 Test Electrolyte, Saturated Calcium Sulfate-Magnesium
Hydroxide Solution—Add 5.0 g of reagent grade CaSO ·2H O,
4 2
0.1 g of reagent grade Mg(OH) , to 1000 mL of Type IV or
better reagent grade water (see Specification D1193).
6.2 Coulometer Solution—Add 235 g of reagent grade
CuSO ·5H O, 27 mL 98 % H SO,50cm undenatured ethyl
4 2 2 4
alcohol to 900 mL of Type IV or better reagent grade water.
6.3 Anode Cleaning Solution—Add 250 g of reagent grade
CrO to 1000 mL of Type IV or better reagent grade water.
7. Precautions
7.1 Eye protection and skin protection are required when
handling the coulometer solution and when handling the FIG. 3 Test Specimen Preparation from Cast Anode
G97−97 (2007)
8.1.2.2 Tooth set ( cm)—Band saw = 0.05 to 0.13, power
hacksaw = 0.038 to 0.076.
8.1.2.3 End relief angle—Band saw = 10 to 12°.
8.1.2.4 Clearance angle—Band saw = 20 to 30°, power
hacksaw = 20 to 30°.
8.2 Rinse each machined test specimen with water, rinse
with acetone, dry in an oven at 105°C for 30 min, cool, and
weigh to the nearest 0.1 mg. (Warning—The specimens
should be handled with clean gloves at all times after the
acetone rinsing step to avoid contamination of the specimens.)
8.3 Mask each weighed test specimen with electroplater’s
tape. Start 100 mm from the faced end and extend to approxi-
mately13mmfromthenon-facedend.Theareaexposedtothe
electrolyte will be the faced end, plus the side area for a length
of 100 mm. This exposed area is 41.2 cm . A current flow
through the test circuit of 1.60 mA results in an anode current
densit
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