ASTM G97-97(2002)e1
(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 describes 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 (CaSO42H 2O), 20 % bentonite clay, and 5 % sodium sulfate (Na 2SO4). 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.
General Information
Relations
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
e1
Designation: G 97 – 97 (Reapproved 2002)
Standard Test Method for
Laboratory Evaluation of Magnesium Sacrificial Anode Test
Specimens for Underground Applications
ThisstandardisissuedunderthefixeddesignationG 97;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Cautionary notes were moved into the section text editorially October 2002.
1. Scope G 15 Terminology Relating to Corrosion and Corrosion
Testing
1.1 This test method describes a laboratory procedure that
G 16 Guide forApplying Statistics toAnalysis 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
3.1 A known direct current is passed through test cells
typically consists of 75 % gypsum (CaSO ·2H O), 20 % ben-
4 2
connected in series. Each test cell consists of a pre-weighed
tonite clay, and 5 % sodium sulfate (Na SO ). The calcium
2 4
test magnesium alloy anode specimen, a steel pot container
sulfate, magnesium hydroxide test electrolyte simulates the
cathode, and a known electrolyte. Test specimen oxidation
long term environment around an anode installed in the
potential is measured several times during the 14-day test and
gypsum-bentonite-sodium sulfate backfill.
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 toTerminology G 15 for terms used in this test method. 4. Significance and Use
4.1 This test is a guide for evaluating magnesium anodes.
1.3 This standard does not purport to address all of the
The degree of correlation between this test and service perfor-
safety concerns, if any, associated with its use. It is the
mance has not been fully determined.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Apparatus
bility of regulatory limitations prior to use. For specific
5.1 The basic test equipment consists of the following:
precautions, See Section 7 and Paragraph 8.1.1.
5.1.1 Direct Current Power Source,(optional), capable of
2. Referenced Documents
delivering at least 2 mA and 12 V.
5.1.2 Steel Cathode Test Pot, as shown in Fig. 1.
2.1 ASTM Standards:
5.1.3 Copper Coulometer, as shown in Fig. 2, or Electronic
D 1193 Specification for Reagent Water
Coulometer.
G 3 PracticeforConventionsApplicable to Electrochemical
5.1.4 Saturated Calomel Reference Electrode.
Measurements in Corrosion Testing
5.1.5 Electrometer, with an input impedance of 10 or
greater ohms.
This test method is under the jurisdiction of ASTM Committee G01 on
5.1.6 Balance, 100-g capacity with 0.1 mg sensitivity.
Corrosion of Metals, and is the direct responsibility of Subcommittee G01.10 on
Corrosion in Soils.
Current edition approved Oct. 10, 1997. Published December 1997. Originally
e1
published as G 97 – 89. Last previous edition G 97 – 89 (1995) .
2 4
Annual Book of ASTM Standards, Vol 11.01. Available from National Fire Protection Association, Inc., Batterymarch Park,
Annual Book of ASTM Standards, Vol 03.02. Quincy, MA 02269.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
e1
G 97 – 97 (2002)
7. Precautions
7.1 Eye protection and skin protection are required when
handling the coulometer solution and when handling the
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.
FIG. 1 Detail of Test Pot
FIG. 2 Copper Coulometer
5.1.7 Drying Oven, with temperature capability of 110°C or
higher.
6. Reagents
6.1 Test Electrolyte, Saturated Calcium Sulfate-Magnesium
HydroxideSolution—Add5.0gofreagentgradeCaSO ·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 D 1193).
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. FIG. 3 Test Specimen Preparation from Cast Anode
e1
G 97 – 97 (2002)
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.
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
density of 0.039 mA/cm .
8.4 Brush the test pots usin
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.