1、Designation: G 111 97 (Reapproved 2006)Standard Guide forCorrosion Tests in High Temperature or High PressureEnvironment, or Both1This standard is issued under the fixed designation G 111; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, the 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 guide covers procedures, specimens, and equip-ment for conducting laboratory corrosion tests o
3、n metallicmaterials under conditions of high pressure (HP) or thecombination of high temperature and high pressure (HTHP).See 3.2 for definitions of high pressure and temperature.1.2 Tests conducted under HP or HTHP by their nature havespecial requirements. This guide establishes the basic consid-er
4、ations that are necessary when these conditions must beincorporated into laboratory corrosion tests.1.3 The procedures and methods in this guide are applicablefor conducting mass loss corrosion, localized corrosion, andelectrochemical tests as well as for use in environmentallyinduced cracking tests
5、 that need to be conducted under HP orHTHP conditions.1.4 The primary purpose for this guide is to promoteconsistency of corrosion test results. Furthermore, this guidewill aid in the comparison of corrosion data between labora-tories or testing organizations that utilize different equipment.1.5 The
6、 values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-pria
7、te safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E8 Test Methods for Tension Testing of Metallic MaterialsG1 Practice for Preparing, Cleaning, and Evaluating Cor-rosion Test SpecimensG3 Practice for Conv
8、entionsApplicable to ElectrochemicalMeasurements in Corrosion TestingG5 Reference Test Method for Making Potentiostatic andPotentiodynamic Anodic Polarization MeasurementsG15 Terminology Relating to Corrosion and CorrosionTestingG30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimen
9、sG31 Practice for Laboratory Immersion Corrosion Testingof MetalsG34 Test Method for Exfoliation Corrosion Susceptibilityin 2XXX and 7XXX Series Aluminum Alloys (EXCOTest)G38 Practice for Making and Using C-Ring Stress-Corrosion Test SpecimensG39 Practice for Preparation and Use of Bent-Beam Stress-
10、Corrosion Test SpecimensG46 Guide for Examination and Evaluation of PittingCorrosionG49 Practice for Preparation and Use of Direct TensionStress-Corrosion Test SpecimensG59 Test Method for Conducting Potentiodynamic Polar-ization Resistance MeasurementsG78 Guide for Crevice Corrosion Testing of Iron
11、-Base andNickel-Base Stainless Alloys in Seawater and OtherChloride-Containing Aqueous EnvironmentsG 106 Practice for Verification ofAlgorithm and Equipmentfor Electrochemical Impedance Measurements3. Terminology3.1 Definitions:3.1.1 The definitions of terms given in Terminology G15shall be consider
12、ed as applying to this guide.3.2 Definitions of Terms Specific to This Standard:3.2.1 high pressurea pressure above ambient atmosphericpressure that cannot be contained in normal laboratory glass-ware. Typically, this is greater than 0.07 MPa (10 psig).1This guide is under the jurisdiction of ASTM C
13、ommittee G01 on Corrosion ofMetals and is the direct responsibility of Subcommittee G01.05 on LaboratoryCorrosion Tests.Current edition approved May 1, 2006. Published May 2006. Originallyapproved in 1992. Last previous edition approved in 1997 as G 11197.2For referenced ASTM standards, visit the AS
14、TM 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 onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unit
15、ed States.3.2.2 high temperaturetemperatures above ambient labo-ratory temperature where sustained heating of the environmentis required.4. Summary of Guide4.1 This guide describes the use of corrosion coupons,stressed SCC specimens, and electrochemical electrodes in HPand HTHP environments. It also
16、 includes guidelines for the useof high pressure test cells with these specimens to conductreproducible, accurate corrosion test data.4.2 Typically, HP and HPHT tests involve exposure of testspecimens to a liquid (aqueous or non-aqueous), gaseous ormultiphase environment, or both, in an appropriate
17、test cell.The test cell must be able to resist corrosion and environmentalcracking in the test environment while containing the pressur-ized, heated environment. Furthermore, the test specimens inthe HP or HPHT test, or both, can be exposed in either stressedor unstressed condition in either the fre
18、e corroding state orunder electrochemical polarization.5. Significance and Use5.1 HP and HTHP corrosion tests are commonly used toevaluate the corrosion performance of metallic materials underconditions that attempt to simulate service conditions thatinvolve HP or HTHP in combination with service en
19、viron-ments. Examples of service environments where HPand HTHPcorrosion tests have been utilized include chemical processing,petroleum production and refining, food processing, pressur-ized cooling water, electric power systems and aerospacepropulsion.5.2 For the applications of corrosion testing li
20、sted in 5.1, theservice involves handling corrosive and potentially hazardousmedia under conditions of high pressure or high temperature,or both. The temperature and pressure usually enter directlyinto the severity of the corrosion process. Consequently, thelaboratory evaluation of corrosion severit
21、y cannot be per-formed in conventional low pressure glassware without makingpotentially invalid assumptions as to the potential effects ofhigh temperature and pressure on corrosion severity.5.3 Therefore, there is a substantial need to provide stan-dardized methods by which corrosion testing can be
22、performedunder HP and HTHP. In many cases, however, the standardsused for exposure of specimens in conventional low pressureglassware experiments cannot be followed due to the limita-tions of access, volume and visibility arising from the con-struction of high pressure test cells. This guide refers
23、toexisting corrosion standards and practices as applicable andthen goes further in areas where specific guidelines forperforming HP and HTHP corrosion testing are needed.6. Apparatus6.1 The test cell shall be constructed to applicable standardsand codes so that it will have an adequate pressure rati
24、ng tosafely handle the test pressure.6.2 The test cell shall be made of materials that arecorrosion resistant and effectively non-reactive with the testenvironment.6.2.1 The term effectively non-reactive shall mean that thetest cell shall be free of significant mass loss or localizedcorrosion, SCC o
25、r other embrittlement phenomena in the testenvironment, not contaminate the test environment with cor-rosion or other reaction products, and not consume or absorbreactive chemical species from the test environment.6.3 The test cell shall have a seal mechanism that canwithstand both the pressures, te
26、mperatures, and corrosiveenvironment to be used in the test. Periodic hydrostatic testingof the test cell is recommended to ensure pressure capabilities.6.4 The test cell shall be designed to have the necessaryinlet and outlet ports to allow the test environment to beestablished in a controllable ma
27、nner, monitored and sampledduring the exposure period, released in a controlled manner atthe completion of the test, and if over temperature or pressureconditions may occur, adequate over pressure release and overtemperature control equipment should be utilized.6.5 In cases where external loading fi
28、xtures are used forstressing specimens in the HP and HTHP test environment,specially designed feed-throughs shall be used which providefor a minimum of friction force.6.6 Test cell feed-throughs required for external stressingmay be designed to balance the internal pressure in the testvessel.6.7 Any
29、 frictional or pressure forces (or thermal expansion)acting on the specimen through the stressing fixtures must betaken into account when determining the actual load on thespecimen.6.8 Stressing and electrode feed-throughs shall be designedso that the electrodes or stressing rods and specimens canno
30、t beejected from the test cell under pressure. Furthermore, theyshall provide for electrical isolation of the specimen from thetest cell unless galvanic coupling is specifically desired.6.9 Gripping devices shall be designed such that they are incompliance with Test Method E8where application of loa
31、d tothe specimen is required.7. Reagents7.1 In corrosion testing, providing a reproducible chemicalenvironment in which to expose the corrosion test specimens isnecessary.7.2 In cases where the test environment is established by themixing of chemicals in the laboratory, chemicals of reagentgrade pur
32、ity with known contaminant levels are recommended.Simulations of service environments can be formulated inwhich laboratory corrosion tests can be conducted.7.3 In HP/HTHP corrosion testing, a common practice is toconduct tests in environments that have been sampled andretrieved from field or plant l
33、ocations. In both cases describedin 7.2 and 7.3, detailed information as to the chemicalcomposition of the environment should be obtained. Particularattention should be given to the levels of impurities andcontaminants that may be in the environment. Furthermore,under some conditions, these environm
34、ents may be prone tochanges after sampling or during testing which can affect thecorrosion test results.7.4 In many cases, the test cells used to conduct HP tests arelimited in volume and may not be designed to accommodatereplenishment of the environment. Therefore, monitoring thechemical compositio
35、n of the environment during the exposureG 111 97 (2006)2may be necessary to identify if depletion of reactive constitu-ents or concentration of constituents has occurred. In somecases, replenishment or changing of the test environment maybe necessary so that a valid corrosion test can be conducted.7
36、.5 In all cases, it is recommended that the test environmentbe fully documented with respect to its chemical composition.8. Test Specimens8.1 Preparation of Specimens:8.1.1 The primary objective is to prepare a reproduciblemetallic surface with an absolute minimum of coldworkingfollowed by cleaning
37、and degreasing.8.1.2 Since test cells for HP and HTHP tests are usually ofmetallic construction, care must be taken to electrically isolatethe specimens from the test cell unless galvanic coupling isspecifically desired in the test. In cases where the test cell isused as a member of a galvanic coupl
38、e, care must be taken toensure that the galvanic action (anodic or cathodic) does notdegrade the integrity of the test cell.8.2 Corrosion Specimens:8.2.1 Prepare specimens used in HP or HTHP corrosiontests in accordance with Practices G1and G31. Commonly,test cells used for HP and HTHP exposure test
39、s are restricted involume. The available volume in the test cell often decreaseswith increasing pressure rating. Therefore, it is frequentlynecessary to restrict the size and surface area of corrosioncoupons used in HP and HTHP corrosion tests.8.2.2 The ratio of solution volume-to-specimen surface a
40、reais important and a minimum ratio of 30 mL/cm2should bemaintained, where possible. If the ratio drops below this level,it should be shown that there will not be an unacceptably highdepletion rate of important environmental constituents, or therewill not be an undesirable amount of metal ion impuri
41、tiesadded into the test environment during the period of exposure.In all cases, the solution volume-to-specimen surfaces areaused in the test should be stated. If the test cell, specimenholders or stressing fixtures can contribute to the conditionsstated above then they should be included in the cal
42、culation ofspecimen surface area.8.3 Stressed Corrosion Specimens:8.3.1 Both self stressed and externally stressed specimensare acceptable for testing at HP and HTHP. Methods for thefabrication and use of appropriate stressed specimens are givenin the referenced documents. These include tension, ben
43、t beam,C-ring, and U-bend specimens in accordance with PracticesG49, G39, G38, and G30, respectively. Fracture mechanicsspecimens can also be accommodated.8.3.2 For similar reasons given in 8.2, when testing multiplespecimens, it is recommended that the size of the specimens berestricted to the smal
44、lest applicable specimen provided forunder the appropriate standards.8.3.3 Due to the limited access of the specimens in HP andHTHP tests, self stressed specimens are usually more conve-nient than specimens that require external stressing fixtures.8.3.4 In cases such as direct tension and fracture m
45、echanicstests, use of external loading frames and fixtures in conjunctionwith HP and HTHP corrosion tests may be desirable. In thesecases, take both the frictional (sealing) forces and pressureforces acting on the specimens into account when determiningthe effect of applied stress.8.4 Electrochemica
46、l Electrodes:8.4.1 Prepare electrodes for use in HP and HTHP corrosionstudies as described in Practice G3, Test Method G5, andPractices G59and G 106.8.4.2 Cylindrical electrode specimens where only the lowerportion of the electrode is exposed to the liquid phase of testenvironment and where the elec
47、trical connections are madeexternally to the test cell are a convenient geometry. Care mustbe taken to electrically isolate the electrodes from the test cell.Other electrode geometries and designs may be used thatfacilitate feed-through and electrical isolation.8.4.3 A critical portion of the HP or
48、HTHP electrochemicalsystem is the design and construction of the reference elec-trode. It is common to use external reference cells that usestable reference systems such as Ag/AgCl or other stableelectrochemical reference system that can be enclosed in aseparate pressure containing compartment. This
49、 cell is thenconnected to the test cell via a salt bridge and is pressurebalanced with the test cell to minimize ingress of contaminantsinto either the test cell or the reference electrode. Alternatively,an inert or corroding metal electrode can be used as apseudo-reference electrode in some cases. Examples of suchpseudo-reference electrodes include platinum, graphite, orother metal with known stable corrosion potential. However,one problem that can occur with this technique is a drift inreference potential with time. Care should be taken whenemploying such methods. These pseudo-ref
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