1、Designation: G 162 99 (Reapproved 2004)Standard Practice forConducting and Evaluating Laboratory Corrosions Tests inSoils1This standard is issued under the fixed designation G 162; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers procedures for conducting labora-tory corrosion tests in soils to evaluate the corrosi
3、ve attack onengineering materials.1.2 This practice covers specimen selection and preparation,test environments, and evaluation of test results.1.3 This practice does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standa
4、rd to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 1654 Test Method for Evaluation of Painted or CoatedSpecimens Subjected to Corrosive Env
5、ironmentsD 2570 Test Method for Simulated Service Corrosion Test-ing of Engine CoolantsG 1 Practice for Preparing, Cleaning, and Evaluating Cor-rosion Test SpecimensG 3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG 4 Guide for Conducting Corrosion Coupon Te
6、sts in FieldApplicationsG 16 Practice For Applying Statistics to Analysis of Corro-sion DataG 31 Practice for Laboratory Immersion Corrosion Testingof MetalsG 46 Guide for Examination and Evaluation of PittingCorrosionG 51 Test Method for pH of Soil for Use in CorrosionTestingG 57 Test Method for Fi
7、eld Measurement of Soil ResistivityUsing the Wenner Four-Electrode MethodG 71 Guide for Conducting and Evaluating Galvanic Cor-rosion Tests in ElectrolytesG 102 Practice for Calculation of Corrosion Rates andRelated Information from Electrochemical Measurements3. Significance and Use3.1 This practic
8、e provides a controlled corrosive environ-ment that has been utilized to produce relative corrosioninformation.3.2 The primary application of the data from this practice isto evaluate metallic materials for use in soil environments.3.3 This practice may not duplicate all field conditions andvariable
9、s such as stray currents, microbiologically influencedcorrosion, non-homogeneous conditions, and long cell corro-sion. The reproducibility of results in the practice is highlydependent on the type of specimen tested and the evaluationcriteria selected as well as the control of the operatingvariables
10、. In any testing program, sufficient replicates shouldbe included to establish the variability of the results.3.4 Structures and components may be made of severaldifferent metals; therefore, the practice may be used to evaluategalvanic corrosion effects in soils (see Guide G 71).3.5 Structures and c
11、omponents may be coated with sacrifi-cial or noble metal coatings, which may be scratched orotherwise rendered discontinuous (for example, no coating onthe edges of metal strips cut from a wide sheet). This test isuseful to evaluate the effect of defective metallic coatings.3.6 Structures and compon
12、ents may be coated or jacketedwith organic materials (for example, paints and plastics), andthese coatings and jackets may be rendered discontinuous. Thetest is useful to evaluate the effect of defective or incompletelycovering coatings and jackets.3.7 The corrosivity of soils strongly depends on so
13、luble saltcontent (related parameters are soil resistivity, see Test MethodG 57, and chemistry), acidity or alkalinity (measured by soilpH, see Test Method G 51), and oxygen content (loose, forexample, sand, or compact, for example, clay, soils are extremeexamples). The manufacturer, supplier, or us
14、er, or combinationthereof, should establish the nature of the expected soil1This guide is under the jurisdiction of ASTM Committee G01 on Corrosion ofMetals and is the direct responsibility of Subcommittee G01.10 on Corrosion inSoils.Current edition approved Nov 1, 2004. Published November 2004. Ori
15、ginallyapproved in 1999. Last previous edition approved in 1999 as G 162 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onth
16、e ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.environment(s) and select the test environment(s) accordingly.Multiple types of soil can be used to determine the effect of thisvariable.4. Test Apparatus and Conditions4
17、.1 ContainerThe container for the soil shall be madefrom a material that is not affected by the soil environment andthat does not affect the soil. Container materials, such as glass,plastic, or corrosion-resistant metal or alloy, can be used;however, electrically conductive containers must be electr
18、o-chemically isolated from the specimens. The size of thecontainer is determined by the volume of soil required for thetest. A minimum of 40 cm3should be used for each 1 cm2ofexposed metal surface area (see Fig. 1).4.2 Soil EnvironmentThe container is filled with a soilsample of choice. A soil sampl
19、e from a specific outdoorlocation may be retrieved for the test, or a soil sample may beprepared with a specific property and chemistry. If necessary,physical and chemical characteristics of the soil may bedetermined.4.2.1 A field soil sample may be utilized for purposes ofconducting a soil corrosio
20、n test in a specific environment.4.2.2 Laboratory soil samples may be prepared by usingwashed sand, (that is, No. 2 silica sand) clean clay (that is,bentonite) or other uniform known media.4.2.3 Soil ChemistryThe field soil sample and the labora-tory soil sample are saturated with a known electrolyt
21、e chosenfor the test. Typically, the electrolyte is added to the soil ofchoice in the container. A typical electrolyte for use withwashed sand is ASTM corrosive water (see Test MethodD 2570). With field soil samples, deionized or distilled water(see Test Method D2570) is commonly used. Periodically,
22、deionized or distilled water (see Specification D 1193) is addedto maintain the soil in a saturated condition. A non-saturatedcondition can be maintained if desired.4.2.4 TemperatureThe test is conducted under laboratoryambient temperature unless the effect of temperature is beingevaluated.4.2.5 Tes
23、t SpecimenThe test specimen is buried in the soilwithin the container and is prepared as discussed in Section 5.5. Test Specimen5.1 MaterialPrepare the test specimens from the samematerial as that used in the structures or components beingstudied. Alternatively, use test specimens from the actualpro
24、ducts.5.2 Size and Shape:5.2.1 The size and shape of test specimens are dependent onseveral factors and cannot be rigidly defined. When determin-ing corrosion behavior of metals in the laboratory, it isadvisable to use the largest specimens permissible within theconstraints of the test equipment. In
25、 general, the ratio ofsurface area to metal volume should be large in order to obtainmaximum corrosion loss per specimen weight. However,sufficient thickness should be employed to minimize thepossibility of perforation of the specimen during the testexposure unless an evaluation of perforation susce
26、ptibility is ofinterest. When modeling large structures or components, thesize of the specimens should be as large as practical. Whenmodeling small components, the specimen size should be asclose as possible to that of the component modeled. When thestructure or component is made of two or more meta
27、ls, thesurface area ratio of the test specimen should be similar to thestructure or component being modeled.5.2.2 When modeling service applications, the shapes of thespecimens should approximate the shapes in the application.Complex shapes are frequently simplified for testing purposes.For some tes
28、ts, the specimen may be taken from the manufac-turing line or cut from manufactured pieces (for example, shortsections of pipes, wires, cables).5.3 Specimen Preparation:5.3.1 Prepare the edges of the test specimens so as toeliminate all sheared or cold worked metal, except for coldworking introduced
29、 by stamping for identification. Shearingcan, in some cases, introduce residual stress that may causeconsiderable attack. Therefore, do not use specimens withsheared edges unless this effect is being evaluated. Finish theedges by machining or polishing. The slight amount of coldwork resulting from t
30、he machining process should not intro-duce serious error.5.3.2 The specimen metallurgical and surface conditionshould be similar to the application being modeled. In all cases,remove surface contamination, such as dirt, grease, oil andthick oxides, prior to weighing and exposure to the testenvironme
31、nt (see Practice G 1).5.3.3 The effect of damage areas on coated specimens maybe of interest. In this circumstance, artificially introduceuniform damages, similar in size to the expected field damage.Some methods of applying standardized mechanical damage tocoated specimens are presented in Test Met
32、hod D 1654.5.3.4 Introduce a specimen identification system that willendure throughout the test period. Edged notches, drilled holes,stamped numbers, and tags are some of the methods used foridentification. The identification system must not induce cor-rosion attack in any way.5.4 Number of Specimen
33、s:5.4.1 The number of scheduled periodic specimen removalsduring the test should include duplicate and, preferably, tripli-cate specimens for any given test period to determine thevariability in the corrosion behavior. The effect of the numberof replications on the evaluation of the results is set f
34、orth inPractice G 16.5.4.2 If the test specimens are made of galvanically coupleddissimilar metals, control specimens should also be tested toFIG. 1 Apparatus for Conducting Laboratory Corrosion Tests inSoilsG 162 99 (2004)2provide corrosion rates of the individual metals and alloys(without coupling
35、) for comparison. These specimens should beof the same alloys, shapes, sizes, surface, and metallurgicalcondition as the materials in the couple.6. Test Procedure6.1 Test AssemblyIntroduce the test soil into the containerno less than 2 cm from the top of the container. Bury thespecimen (or specimens
36、) within the soil. The specimen shouldnot contact the container and should be completely buriedunless the effect of partial burial is desired (see Fig. 1).6.1.1 The corrosion behavior of metals in soil is influencedby the compaction of the soil around the metal and the effect ofpore structure of the
37、 soil on the oxygen transport to the metalsurface. Therefore, when simulating site conditions, the testsoil shall be compacted appropriately.6.1.2 Space the specimens (if more than one is buried withina container) such that a minimum of 40 cm3of test soilsurrounds each square centimetre of exposed s
38、urface area.6.1.3 The appropriate electrolyte is introduced to the con-tainer such that the soil is saturated and the level of liquid is atthe same height as the level of the soil within the container.Deionized or distilled water (see Specification D 1193) isadded periodically to maintain saturation
39、 in the soil. Thecontainer may be loosely covered to minimize evaporation.6.1.4 To simulate conditions in which soil is not watersaturated, the distilled or deionized water is added periodicallyto maintain a water level below the test specimen.6.2 Test Duration:6.2.1 The duration of the exposure to
40、the test environmentshould be sufficient to allow prediction of the corrosionbehavior for the entire service duration. Measure corrosiondata as a function of time until a curve is developed that onecan extrapolate to the service duration, provided that steady-state conditions have been reached and t
41、hat no transientenvironmental conditions are expected in service to affect thissteady state.6.2.2 If the exposure time is extensive, some of the impor-tant constituents of the test medium may be depleted. There-fore, the test environment may be altered and provide resultsthat are not representative.
42、6.2.3 Remove test specimens based on a preplanned sched-ule.7. Evaluation of Test Specimens7.1 Measurements During ExposureData recorded duringexposure may include potential measurements of the testspecimens and galvanic current measurements in galvaniccouples. Measure the potentials against a suita
43、ble referencehalf-cell as recommended in Practice G 3. Current data can beconverted into corrosion rate based on Faradays law when allof the current is due to the corrosion reaction (see PracticeG 102).7.2 Measurements After Removal:7.2.1 After removal, take samples of corrosion products forchemical
44、 and physical analysis. Record visual observationsafter taking color photographs of each specimen. Clean thespecimens in accordance with Practice G 1, and weigh thespecimens to determine the corrosion mass loss, which can beconverted to corrosion rate as set forth in Practice G 31.Additional recomme
45、ndations for specimen cleaning are inGuide G 4 and Practice G 31.7.2.2 Some examples in which mass loss measurements arenot always possible or meaningful are (1) specimens withorganic coating and jacketing, (2) specimens made of solderedassemblies, and (3) specimens subject only to localized corro-s
46、ion (for example, pitting or cracking). In these cases, base thecorrosion evaluation on visual assessment, loss of tensilestrength, loss of thickness, or on other measurement tech-niques. Analyze localized corrosion, such as pitting, using themethods described in Guide G 46. Analyze specimens under-
47、going crevice corrosion with depth of attack measurements andwith detailed description, including changes taking place at theedges as well as on the surfaces. In addition, measure changesin physical properties, such as tensile strength and loss ofductility. In some cases, metallographic examination
48、of speci-men cross sections can be used to determine the depth ofcorrosion.7.2.3 Compare the behavior of galvanic test specimens tothat of exposed uncoupled controls of the individual anode andcathode materials. Subtracting the results found on the controlsamples from the values of the coupled speci
49、mens yields thecorrosion behavior of anode and cathode materials due tocoupling.7.2.4 Where replicate specimens are exposed, apply statis-tical analysis of the data, as set forth in Practice G 16, togenerate confidence intervals for predictive purposes.8. Report8.1 Report the Following Information:8.1.1 A detailed description of the exposed specimen, in-cluding alloy and temper, metallurgical history, chemicalcomposition, processing parameters for formed parts, coatingchemistry, weight and thickness, and specific details of prod-ucts, such as jacketed cables or wire.8.1.2 Ph
