ASTM G200-20

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 pH (see Test Method G51), and 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 in-situ in the field or 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 in-situ or 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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

• Status: Published
• Publication Date: 31-Oct-2020
• ICS: 13.080.30 - Biological properties of soils
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.10 - Corrosion in Soils

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: G200 − 20
Standard Test Method for
Measurement of Oxidation-Reduction Potential (ORP) of
1
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 G3 Practice for Conventions Applicable to Electrochemical
Measurements in Corrosion Testing
1.1 This test method covers a procedure and related test
G51 Test Method for Measuring pH of Soil for Use in
equipment for measuring oxidation-reduction potential (ORP)
Corrosion Testing
of soil samples in-situ or removed from the ground.
G57 Test Method for Field Measurement of Soil Resistivity
1.2 The procedure in Section 9 is appropriate for field and
Using the Wenner Four-Electrode Method
laboratory measurements.
G187 Test Method for Measurement of Soil Resistivity
Using the Two-Electrode Soil Box Method
1.3 Accurate measurement of oxidation-reduction potential
aids in the analysis of soil corrosivity and its impact on buried G193 Terminology and Acronyms Relating to Corrosion
G215 Guide for Electrode Potential Measurement
metallic structure corrosion rates.
1.4 The values stated in inch-pound units are to be regarded
3. Terminology
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
3.1 The terminology used in this test method, if not specifi-
and are not considered standard. cally defined otherwise, shall be in accordance with Terminol-
ogy G193.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.2 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.2.1 calibration solution, n—commercially available solu-
priate safety, health, and environmental practices and deter-
tion with a stable ORP used for calibrating an ORP measuring
mine the applicability of regulatory limitations prior to use.
system (meter and probe).
1.6 This international standard was developed in accor-
3.2.2 ORP—abbreviation for oxidation-reduction potential.
dance with internationally recognized principles on standard-
3.2.3 ORP electrode (probe), n—commercially available
ization established in the Decision on Principles for the
combination two-element electrode (probe) specifically de-
Development of International Standards, Guides and Recom-
signed for the measurement of ORP when used in conjunction
mendations issued by the World Trade Organization Technical
with a compatible ORP meter.
Barriers to Trade (TBT) Committee.
3.2.3.1 Discussion—The combination probe consists of a
2. Referenced Documents platinum electrode and a reference electrode, which are gen-
2 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-
ter specifically designed for the measurement of ORP with
1
This test method is under the jurisdiction of ASTM Committee G01 on internal impedance greater than 10 megohms. Often, the meter
Corrosion of Metals and is the direct responsibility of Subcommittee G01.10 on
is capable of measuring ORPand pH when used in conjunction
Corrosion in Soils.
with the appropriate electrode.
Current edition approved Nov. 1, 2020. Published December 2020. Originally
3.2.4.1 Discussion—Standard voltmeters or multimeters
approvedin2009.Lastpreviouseditionapprovedin2014asG200-09(2014).DOI:
10.1520/G0200-20.
with internal impedances typically less than 10 megohms are
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
not suitable for soil ORP measurements. Pocket style meters
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
where the electrode is an integral part of the meter housing are
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. also not suitable.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
G200 − 20
3.2.5 oxidation-redu
...

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 (Reapproved 2014) G200 − 20
Standard Test Method for
Measurement of Oxidation-Reduction Potential (ORP) of
1
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 in-situ or 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2
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
G15G51 Terminology Relating to Corrosion and Corrosion Test Method for Measuring pH of Soil for Use in Corrosion Testing
(Withdrawn 2010)
G57 Test Method for 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
G193 Terminology and Acronyms Relating to Corrosion
G215 Guide for Electrode Potential Measurement
1
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, 2014Nov. 1, 2020. Published May 2014December 2020. Originally approved in 2009. Last previous edition approved in 20092014 as
G200 - 09.09(2014). DOI: 10.1520/G0200-09R14.10.1520/G0200-20.
2
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’sstandard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
G200 − 20
3. Terminology
3.1 The terminology used in this test method, if not specifically defined otherwise, shall be in accordance with Terminology
G15G193.
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.
3.2.3.1 Discussion—
The combination probe consists of a platinum electrode and a reference electrode, which are generally silver/silver chloride. For
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.megohms. Often, the meter is capable of measuring ORP and pH when used in conjunction with the
appropriate electrode.
...