ASTM G200-09(2014)

Standard Test Method for Measurement of Oxidation-Reduction Potential (ORP) of Soil

SIGNIFICANCE AND USE
5.1 Soil ORP, in conjunction with other soil characteristics such as electrical resistivity (see Test Methods G57 and G187), is used to predict corrosion tendencies of buried metallic structures (for example, pipelines and culverts. The ORP of the soil is one of many factors that influence structure service life. Its measurement is used in the design of new buried structures and in the evaluation of existing buried structures.  
5.2 Soil ORP is a time-sensitive measurement. For an accurate indication of soil corrosivity, the measurement should be made as soon as practicable after removal of the soil sample from the ground.  
5.3 The user of this test method is responsible for determining the significance of reported ORP measurements. ORP alone should typically not be used in characterizing the corrosivity of a particular soil. ORP measurements are appropriate when evaluating oxygen related reactions.  
5.4 ORP measurements can sometimes be quite variable and non-reproducible. This is related, in part, to the general heterogeneity of a given soil. It is also related to the introduction of increased oxygen into the sample after extraction. The interpretation of soil ORP should be considered in terms of its general range rather than as an absolute measurement.  
5.5 ORP measurements can be used to determine if a particular soil has the propensity to support microbiologically influenced corrosion (MIC) attack. These measurements can also be used to provide an indication of whether soil conditions will be aerobic or anaerobic. Appendix X1 provides reference guidelines for general interpretation of ORP data.
SCOPE
1.1 This test method covers a procedure and related test equipment for measuring oxidation-reduction potential (ORP) of soil samples removed from the ground.  
1.2 The procedure in Section 9 is appropriate for field and laboratory measurements.  
1.3 Accurate measurement of oxidation-reduction potential aids in the analysis of soil corrosivity and its impact on buried metallic structure corrosion rates.  
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.5 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

• Status: Historical
• Publication Date: 30-Apr-2014
• ICS: 13.080.30 - Biological properties of soils
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.10 - Corrosion in Soils

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: G200 − 09 (Reapproved 2014)
Standard Test Method for
Measurement of Oxidation-Reduction Potential (ORP) of
Soil
This standard is issued under the fixed designation G200; 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 G57 Test Method for Field Measurement of Soil Resistivity
Using the Wenner Four-Electrode Method
1.1 This test method covers a procedure and related test
G187 Test Method for Measurement of Soil Resistivity
equipment for measuring oxidation-reduction potential (ORP)
Using the Two-Electrode Soil Box Method
of soil samples removed from the ground.
1.2 The procedure in Section 9 is appropriate for field and
3. Terminology
laboratory measurements.
3.1 The terminology used in this test method, if not specifi-
1.3 Accurate measurement of oxidation-reduction potential
cally defined otherwise, shall be in accordance with Terminol-
aids in the analysis of soil corrosivity and its impact on buried
ogy G15.
metallic structure corrosion rates.
3.2 Definitions of Terms Specific to This Standard:
1.4 The values stated in inch-pound units are to be regarded
3.2.1 calibration solution, n—commercially available solu-
as standard. The values given in parentheses are mathematical
tion with a stable ORP used for calibrating an ORP measuring
conversions to SI units that are provided for information only
system (meter and probe).
and are not considered standard.
3.2.2 ORP—abbreviation for oxidation-reduction potential.
1.5 This standard does not purport to address all of the
3.2.3 ORP electrode (probe), n—commercially available
safety concerns, if any, associated with its use. It is the
combination two-element electrode (probe) specifically de-
responsibility of the user of this standard to establish appro-
signed for the measurement of ORP when used in conjunction
priate safety and health practices and determine the applica-
with a compatible ORP meter.
bility of regulatory limitations prior to use.
3.2.3.1 Discussion—The combination probe consists of a
platinum electrode and a reference electrode, which are gen-
2. Referenced Documents
erally silver/silver chloride. For soil measurements, the probe
2.1 ASTM Standards:
must be sufficiently robust to withstand the rigors of the
D1498 Test Method for Oxidation-Reduction Potential of
measurement. Regardless, the often fragile probe should be
Water
used with caution to avoid damage and maintain measurement
E691 Practice for Conducting an Interlaboratory Study to
reliability.
Determine the Precision of a Test Method
3.2.4 ORP meter, n—commercially available electrical me-
G3 Practice for Conventions Applicable to Electrochemical
ter specifically designed for the measurement of ORP with
Measurements in Corrosion Testing
internal impedance greater than 10 Ω. Often, the meter is
G15 Terminology Relating to Corrosion and Corrosion Test-
3 capable of measuring ORP and pH when used in conjunction
ing (Withdrawn 2010)
with the appropriate electrode.
3.2.4.1 Discussion—Standard voltmeters or multimeters
with internal impedances typically less than 10 Ω are not
This test method is under the jurisdiction of ASTM Committee G01 on
suitableforsoilORPmeasurements.Pocketstylemeterswhere
Corrosion of Metals and is the direct responsibility of Subcommittee G01.10 on
the electrode is an integral part of the meter housing are also
Corrosion in Soils.
Current edition approved May 1, 2014. Published May 2014. Originally not suitable.
approved in 2009. Last previous edition approved in 2009 as G200 - 09. DOI:
3.2.5 oxidation-reduction potential (soil), n—electrical po-
10.1520/G0200-09R14.
tential measurement to determine the tendency of a soil to
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
transfer electrons between its chemical species. It is the
Standards volume information, refer to the standard’s Document Summary page on
measured potential of an inert metal electrode (generally
the ASTM website.
platinum) with respect to a reference electrode such as silver/
The last approved version of this historical standard is referenced on
www.astm.org. silver chloride.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G200 − 09 (2014)
3.2.5.1 Discussion—A soil with a higher, more positive 6. Apparatus
potential has an increased tendency to acquire electrons and be
6.1 The equipment required for the measurement of soil
reduced (aerobic soil conditions). A soil with a lower positive
ORP, either in the field or in the laboratory, consists of:
or negative potential has an increased tendency to lose elec-
6.1.1 ORP Meter.
trons and be oxidized (anaerobic soil conditions). Soil
6.1.2 Compatible Two-Electrode Combination ORP Elec-
oxidation-reduction potential is typically reported in units of
trode (Probe)—A main probe and a backup probe are recom-
millivolts (mV) or volts (1 volt = 1000 mV). Sign convention
mended.
and reference electrodes conform to Practice G3.
NOTE 1—This test method calls for soil ORPmeasurements to utilize a
3.2.6 redox potential, n—synonym for oxidation-reduction
commercially available combination electrode (inert metal and reference
potential.
combined in one probe). Commercially available ORP combination
electrodes are generally platinum (inert metal) with silver/silver chloride
3.2.7 soil sample, n—sample of soil to be tested. The
(reference) in a 3.5 to 4 M KCl electrolyte.
minimum (typical) sample size is 1 qt.
6.1.3 Operating Instructions—For ORP meter and ORP
electrode.
4. Summary of Test Method
6.1.4 Calibration Solution(s)—For verification of measur-
4.1 The measurement procedure, as described in Section 9 ing system accuracy within the range of expected ORPvalues.
of this test method for determining the ORP of a soil sample, Calibration solutions should remain uncontaminated. They
aids in determining the corrosivity of that sample. typically have a published shelf life of no more than 1 year and
should not be used once the shelf life is exceeded. Calibration
4.2 Soil ORP can be measured in a field or laboratory
solutionscanbeobtainedcommerciallyormaybemixedinthe
setting.
laboratory using standard pH buffers (4 and 7) and quinhy-
4.3 While the primary purpose of this test method is drone.
measuring soil ORP, it may also be used as a general indicator
NOTE 2—Commercially available ORP calibration solution values
of ORP in groundwater. Test Method D1498 was specifically
should be appropriate for the combination electrode (platinum and
developed for accurate ORP measurements of aqueous
silver/silver chloride) used. Calibration kits utilizing pH buffers and
quinhydronesolutionsaregenerallyusedfortheplatinumandsilver/silver
samples.
chloride combination electrode.
5. Significance and Use 6.1.5 Clear Plastic or Polyethylene Bags—1 gal (3.785 L)
size is typical, or other convenient means to collect the soil
5.1 Soil ORP, in conjunction with other soil characteristics
sampleandtocompressthesamplewhileundertest.Oneclean
such as electrical resistivity (seeTest Methods G57 and G187),
and dry bag should be used for each sample. Do not reuse.
is used to predict corrosion tendencies of buried metallic
6.1.6 Squirt Bottle and Soft Toothbrush—Bottle with goose-
structures (for example, pipelines and culverts.The ORPof the
neck (or similar) filled with distilled or deionized water and
soil is one of many factors that influence structure service life.
soft toothbrush (or similar) for cleaning ORP electrode after
Its measurement is used in the design of new buried structures
each measurement. Cleaning procedures should be in accor-
and in the evaluation of existing buried structures.
dance with the probe manufacturer’s written instructions and
should in no way damage the probe or otherwise compromise
5.2 Soil ORP is a time-sensitive measurement. For an
accurate indication of soil corrosivity, the measurement should the ORP measurement.
be made as soon as practicable after removal of the soil sample
7. Sampling
from the ground.
7.1 Generally, collected soil samples to be tested in the
5.3 The user of this test method is responsible for determin-
laboratory shall be placed in an appropriate sealable container
ingthesignificanceofreportedORPmeasurements.ORPalone
or polyethylene type bag. This allows containers to be identi-
shouldtypicallynotbeusedincharacterizingthecorrosivityof
fied by location, date/time sample was collected, etc.
a particular soil. ORP measurements are appropriate when
7.2 Soil samples shall be representative of the area of
evaluating oxygen related reactions.
interest.Where the stratum of interest contains a variety of soil
5.4 ORPmeasurementscansometimesbequitevariableand
types, it is desirable to sample each type separately. Soil
non-reproducible. This is related, in part, to the general
samples to be tested in the laboratory shall be allowed to reach
heterogeneity of a given soil. It is also related to the introduc-
room temperature, approximately 68°F (20°C), prior to the
tion of increased oxygen into the sample after extraction. The
ORP measurement. Field measurements shall reflect the soil’s
interpretation of soil ORP should be considered in terms of its
temperature during testing.
general range rather than as an absolute measurement.
8. Calibration and Standardization
5.5 ORP measurements can be used to determine if a
8.1 Turn on the ORP meter in accordance with the meter
particular soil has the propensity to support microbiologically
manufacturer’s written instructions.Allow sufficient warm-up/
influenced corrosion (MIC) attack. These measurements can
stabilization time as specified by the manufacturer.
alsobeusedtoprovideanindicationofwhethersoilconditions
will be aerobic or anaerobic. Appendix X1 provides reference 8.2 Checkthemeter“zero”byshortingtheinputconnection
guidelines for general interpretation of ORP data. in accordance with the manufacturer’s instructions. For a BNC
G200 − 09 (2014)
type connection and probe cable, a paper clip between the or abrade the ORP probe sense element. Place the suitable
meter input center connection and outer shield (ground) sample in a clear plastic bag.
typically suffices. With the input shorted, adjust the me
...

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: G200 − 09 G200 − 09 (Reapproved 2014)
Standard Test Method for
Measurement of Oxidation-Reduction Potential (ORP) of
Soil
This standard is issued under the fixed designation G200; 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 test method covers a procedure and related test equipment for measuring oxidation-reduction potential (ORP) of soil
samples removed from the ground.
1.2 The procedure in Section 9 is appropriate for field and laboratory measurements.
1.3 Accurate measurement of oxidation-reduction potential aids in the analysis of soil corrosivity and its impact on buried
metallic structure corrosion rates.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.5 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:
D1498 Test Method for Oxidation-Reduction Potential of Water
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
G3 Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing
G15 Terminology Relating to Corrosion and Corrosion Testing (Withdrawn 2010)
G57 Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method
G187 Test Method for Measurement of Soil Resistivity Using the Two-Electrode Soil Box Method
3. Terminology
3.1 The terminology used in this test method, if not specifically defined otherwise, shall be in accordance with Terminology
G15.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 calibration solution, n—commercially available solution with a stable ORP used for calibrating an ORP measuring system
(meter and probe).
3.2.2 ORP—abbreviation for oxidation-reduction potential.
3.2.3 ORP electrode (probe), n—commercially available combination two-element electrode (probe) specifically designed for
the measurement of ORP when used in conjunction with a compatible ORP meter.
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 Corrosion in
Soils.
Current edition approved May 1, 2009May 1, 2014. Published July 2009May 2014. Originally approved in 2009. Last previous edition approved in 2009 as G200 - 09.
DOI: 10.1520/G0200-09.10.1520/G0200-09R14.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
3.2.3.1 Discussion—
The combination probe consists of a platinum electrode and a reference electrode, which are generally silver/silver chloride. For
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G200 − 09 (2014)
soil measurements, the probe must be sufficiently robust to withstand the rigors of the measurement. Regardless, the often fragile
probe should be used with caution to avoid damage and maintain measurement reliability.
3.2.4 ORP meter, n—commercially available electrical meter specifically designed for the measurement of ORP with internal
impedance greater than 10 Ω. Often, the meter is capable of measuring ORP and pH when used in conjunction with the appropriate
electrode.
3.2.4.1 Discussion—
Standard voltmeters or multimeters with internal impedances typically less than 10 Ω are not suitable for soil ORP measurements.
Pocket style meters where the electrode is an integral part of the meter housing are also not suitable.
3.2.5 oxidation-reduction potential (soil), n—electrical potential measurement to determine the tendency of a soil to transfer
electrons between its chemical species. It is the measured potential of an inert metal electrode (generally platinum) with respect
to a reference electrode such as silver/silver chloride.
3.2.5.1 Discussion—
A soil with a higher, more positive potential has an increased tendency to acquire electrons and be reduced (aerobic soil
conditions). A soil with a lower positive or negative potential has an increased tendency to lose electrons and be oxidized
(anaerobic soil conditions). Soil oxidation-reduction potential is typically reported in units of millivolts (mV) or volts (1 volt =
1000 mV). Sign convention and reference electrodes conform to Practice G3.
3.2.6 redox potential, n—synonym for oxidation-reduction potential.
3.2.7 soil sample, n—sample of soil to be tested. The minimum (typical) sample size is 1 qt.
4. Summary of Test Method
4.1 The measurement procedure, as described in Section 9 of this test method for determining the ORP of a soil sample, aids
in determining the corrosivity of that sample.
4.2 Soil ORP can be measured in a field or laboratory setting.
4.3 While the primary purpose of this test method is measuring soil ORP, it may also be used as a general indicator of ORP
in groundwater. Test Method D1498 was specifically developed for accurate ORP measurements of aqueous samples.
5. Significance and Use
5.1 Soil ORP, in conjunction with other soil characteristics such as electrical resistivity (see Test Methods G57 and G187), is
used to predict corrosion tendencies of buried metallic structures (for example, pipelines and culverts. The ORP of the soil is one
of many factors that influence structure service life. Its measurement is used in the design of new buried structures and in the
evaluation of existing buried structures.
5.2 Soil ORP is a time-sensitive measurement. For an accurate indication of soil corrosivity, the measurement should be made
as soon as practicable after removal of the soil sample from the ground.
5.3 The user of this test method is responsible for determining the significance of reported ORP measurements. ORP alone
should typically not be used in characterizing the corrosivity of a particular soil. ORP measurements are appropriate when
evaluating oxygen related reactions.
5.4 ORP measurements can sometimes be quite variable and non-reproducible. This is related, in part, to the general
heterogeneity of a given soil. It is also related to the introduction of increased oxygen into the sample after extraction. The
interpretation of soil ORP should be considered in terms of its general range rather than as an absolute measurement.
5.5 ORP measurements can be used to determine if a particular soil has the propensity to support microbiologically influenced
corrosion (MIC) attack. These measurements can also be used to provide an indication of whether soil conditions will be aerobic
or anaerobic. Appendix X1 provides reference guidelines for general interpretation of ORP data.
6. Apparatus
6.1 The equipment required for the measurement of soil ORP, either in the field or in the laboratory, consists of:
6.1.1 ORP Meter.
6.1.2 Compatible Two-Electrode Combination ORP Electrode (Probe)—A main probe and a backup probe are recommended.
NOTE 1—This test method calls for soil ORP measurements to utilize a commercially available combination electrode (inert metal and reference
combined in one probe). Commercially available ORP combination electrodes are generally platinum (inert metal) with silver/silver chloride (reference)
in a 3.5 to 4 M KCl electrolyte.
G200 − 09 (2014)
6.1.3 Operating Instructions—For ORP meter and ORP electrode.
6.1.4 Calibration Solution(s)—For verification of measuring system accuracy within the range of expected ORP values.
Calibration solutions should remain uncontaminated. They typically have a published shelf life of no more than 1 year and should
not be used once the shelf life is exceeded. Calibration solutions can be obtained commercially or may be mixed in the laboratory
using standard pH buffers (4 and 7) and quinhydrone.
NOTE 2—Commercially available ORP calibration solution values should be appropriate for the combination electrode (platinum and silver/silver
chloride) used. Calibration kits utilizing pH buffers and quinhydrone solutions are generally used for the platinum and silver/silver chloride combination
electrode.
6.1.5 Clear Plastic or Polyethylene Bags—1 gal (3.785 L) size is typical, or other convenient means to collect the soil sample
and to compress the sample while under test. One clean and dry bag should be used for each sample. Do not reuse.
6.1.6 Squirt Bottle and Soft Toothbrush—Bottle with gooseneck (or similar) filled with distilled or deionized water and soft
toothbrush (or similar) for cleaning ORP electrode after each measurement. Cleaning procedures should be in accordance with the
probe manufacturer’s written instructions and should in no way damage the probe or otherwise compromise the ORP measurement.
7. Sampling
7.1 Generally, collected soil samples to be tested in the laboratory shall be placed in an appropriate sealable container or
polyethylene type bag. This allows containers to be identified by location, date/time sample was collected, etc.
7.2 Soil samples shall be representative of the area of interest. Where the stratum of interest contains a variety of soil types,
it is desirable to sample each type separately. Soil samples to be tested in the laboratory shall be allowed to reach room temperature,
approximately 68°F (20°C), prior to the ORP measurement. Field measurements shall reflect the soilssoil’s temperature during
testing.
8. Calibration and Standardization
8.1 Turn on the ORP meter in accordance with the meter manufacturer’s written instructions. Allow sufficient warm-up/
stabilization time as specified by the manufacturer.
8.2 Check the meter “zero” by shorting the input connection in accordance with the manufacturer’s instructions. For a BNC type
connection and probe cable, a paper clip between the meter input center connection and outer shield (ground) typically suffices.
With the input shorted, adjust the meter as necessary in accordan
...