1、Designation: G208 12Standard Practice forEvaluating and Qualifying Oilfield and Refinery CorrosionInhibitors Using Jet Impingement Apparatus1This standard is issued under the fixed designation G208; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a generally accepted procedure touse the jet impingement (JI) apparat
3、us for evaluating corrosioninhibitors for oilfield and refinery applications in defined flowconditions.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,
4、if any, associated with its use. It is theresponsibility of the user of this standard 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:2D1141 Practice for the Preparation of Substit
5、ute OceanWaterD1193 Specification for Reagent WaterD4410 Terminology for Fluvial SedimentG1 Practice for Preparing, Cleaning, and Evaluating Corro-sion Test SpecimensG5 Reference Test Method for Making Potentiostatic andPotentiodynamic Anodic Polarization MeasurementsG16 Guide for Applying Statistic
6、s to Analysis of CorrosionDataG31 Guide for Laboratory Immersion Corrosion Testing ofMetalsG46 Guide for Examination and Evaluation of Pitting Cor-rosionG59 Test Method for Conducting Potentiodynamic Polariza-tion Resistance MeasurementsG96 Guide for Online Monitoring of Corrosion in PlantEquipment
7、(Electrical and Electrochemical Methods)G102 Practice for Calculation of Corrosion Rates and Re-lated Information from Electrochemical MeasurementsG106 Practice for Verification of Algorithm and Equipmentfor Electrochemical Impedance MeasurementsG111 Guide for Corrosion Tests in High Temperature orH
8、igh Pressure Environment, or BothG170 Guide for Evaluating and Qualifying Oilfield andRefinery Corrosion Inhibitors in the LaboratoryG184 Practice for Evaluating and Qualifying Oil Field andRefinery Corrosion Inhibitors Using Rotating CageG185 Practice for Evaluating and Qualifying Oil Field andRefi
9、nery Corrosion Inhibitors Using the Rotating CylinderElectrodeG193 Terminology and Acronyms Relating to Corrosion3. Terminology3.1 The terminology used herein shall be in accordance withTerminology D4410, Guide G170, and Terminology G193.4. Summary of Practice4.1 This practice provides a method for
10、evaluating corrosioninhibitor efficiency in jet impingement (JI) apparatus. Themethod uses a well-defined impinging jet set up and mass lossor electrochemical techniques to measure corrosion rates.Measurements are made using three different experimentaldesigns and at several flow rates to evaluate t
11、he inhibitorperformance under increasingly severe hydrodynamic condi-tions.1This practice is under the jurisdiction of ASTM Committee G01 on Corrosionof Metals and is the direct responsibility of Subcommittee G01.05 on LaboratoryCorrosion Tests.Current edition approved May 1, 2012. Published Decembe
12、r 2012. DOI:10.1520/G020812.2For 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 onthe ASTM website.Copyright ASTM International, 100
13、 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 Selection of corrosion inhibitor for oilfield and refineryapplications involves qualification of corrosion inhibitors in thelaboratory (see Guide G170). Field conditions should besimulated in
14、the laboratory in a fast and cost-effective manner.5.2 Oilfield and refinery corrosion inhibitors should provideprotection over a range of flow conditions from stagnant to thatfound during typical production conditions. The inhibitors arenot equally effective over all flow conditions, so it is impor
15、tantto determine the flow conditions in which they are effective.5.3 Severity of hydrodynamic conditions depends on thetype of laboratory methodology. Typically, rotating cylinderelectrode is effective up to 20 Pa of wall shear stress, rotatingcage (RC) is effective between 20 and 200 Pa of wall she
16、arstress, and jet impingement (JI) is effective at wall shear stressabove 200 Pa (1)3of wall shear stress.5.4 The JI test system is relatively inexpensive and usessimple flat specimens.5.5 In this practice, a general procedure is presented toobtain reproducible results using JI simulating the effect
17、s ofdifferent types of coupon materials; inhibitor concentrations;oil, gas, and brine compositions; temperature; pressure; andflow. Erosive effects predominate when the flow rate is veryhigh (typically above 500 Pa) or when sand or solid particlesare present; however, this practice does not cover th
18、e erosiveeffects.6. Apparatus6.1 The actual hydrodynamic conditions in the tests must beknown to enable comparison of results with those obtained inother tests or predictions of inhibitor performance in practicaloperating systems. Hydrodynamic parameters in jet impinge-ment are described in Annex A1
19、. These hydrodynamic rela-tionships are valid only for a specific range and are influencedby the geometry and orientation of specimen and apparatus. Aminor change in any one parameter drastically alters thehydrodynamic parameters.6.2 A proper experimental design must consider the jetvelocity, radial
20、 distance, radius of the electrode (ring or disc),distance between jet nozzle and the electrode, and jet nozzlediameter. Some typical parameters for describing jet impinge-ment apparatus are listed in Table 1.Agood laboratory practicewould be to control, record, and report all the system specifi-cat
21、ions.6.3 Depending on the geometry of apparatus and size andshape of the specimens there are three jet impingementapparatus designs.6.3.1 Design 1:3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.TABLE 1 Parameters to be Reported Along with Test ResultsPa
22、rameter Units RemarksSolution chemistryMaterial chemistrySolution densitySolution viscosityTemperature C or F or KPressure psi or kPa For elevated pressure experimentsJet velocity m/s or cm/s or inch/sSpecimen type ring or discDisc diameter mm or cm or m For disc electrodes onlyring diameter (inner)
23、 mm or cm or m For ring electrodes onlyring diameter (outer) mm or cm or m For ring electrodes onlyradial distance mm or cm or mDistance between jet and the nozzle mm or cm or mRotation speed RPMElectrode diameter or radius mm or cm or mVolume of container cm3Volume of solution cm3Tafel constants, a
24、nodic, cathodic For electrochemical measurementsDescription of counter electrode (size, shape, anddistance from the working electrode)For electrochemical measurementsInitial mass mg or g For mass loss measurementsFinal mass mg or g For mass loss measurementsCorrosion rate in absence of inhibitor mpy
25、 or mm/yrInhibitor efficiency, at each inhibitor concentration %Number of specimensVolume of solution/surface area of the electrode cmInhibitor type continuous or batchInhibitor concentration ppm or vol/vol or mass/volume or mass/massDescription of EIS model Provide the model and elements (for elect
26、rochemicalmeasurements)Solution conductivity Siemens For electrochemical measurementsPresence of oil yes or noIf oil is present, volume of oil cm3Duration of experiments Minutes, hour, dayType of reference electrode For electrochemical measurementsNumber of specimensG208 1226.3.1.1 In this design, t
27、he working electrode is a disc and isexposed only to the stagnation region (Fig. 1)(2-4). Typicaldiameter of the jet nozzle is 0.6 cm and is placed axis-symmetric to the specimen (working electrode). The diameterof the specimen is equal to or less than the diameter of the jetnozzle. The typical dist
28、ance between the jet nozzle tip andspecimen is 3 cm (that is, five times the diameter of the jetnozzle).6.3.1.2 The jet system is a submerged type and it impingesat 90 onto the specimen. Both the counter electrode and thereference electrode are placed adjacent to the nozzle, so thatthey are not in t
29、he path of the jet impinging on the workingelectrode (Fig. 2).6.3.2 Design 2:6.3.2.1 In this design, the specimen is a ring and is exposedonly to the jet region (Fig. 3 and Fig. 4) (5, 6). The diameter ofthe jet nozzle is 0.2 cm. The diameter of the specimen is threetimes the diameter of the jet noz
30、zle (measured to the centerlineof the ring). The inner and outer diameters of the ring specimenare within the jet region. Typical distance between the jetnozzle tip and the specimen is 0.4 cm (that is, two times thediameter of the jet).6.3.2.2 The jet nozzle is manufactured using a nonmetalliccylind
31、er (typically of 1.25 cm of outer diameter with a 0.2 cminlet hole in the center). The length of the cylinder (typically 20cm) is long enough so that the fluid flow stabilizes beforeexiting through the nozzle. The counter electrode is placed atthe end of the jet nozzle (Fig. 5). The reference electr
32、ode isplaced adjacent to the counter electrode.6.3.3 Design 3:6.3.3.1 In this design, the specimen is a disc and is exposedto all three regions of jet (stagnant, jet, and hydrodynamicregions) (see Fig. 6). This design facilitates occurrence oflocalized corrosion as the specimen is under the influenc
33、e ofvarious regions (stagnation, wall jet, and hydrodynamic re-gions).6.3.3.2 The diameter of the jet nozzle is 0.64 cm. Thediameter of the specimen is five times the diameter of the jetNOTE 1r/rjetis less than 2 (Djetis the diameter of the jet, rjetis the radius of the jet, r is the radius of the s
34、pecimen, and H is the distance betweenthe jet tip and the specimen surface). Shaded area indicates the location of the specimen.FIG. 1 Schematic Diagram (Side View) of Impinging Jet on a Specimen in Stagnation RegionG208 123nozzle. Typical distance between the jet nozzle tip and thespecimen is 3.2 c
35、m (that is, five times the diameter of the jet)(7, 8).NOTE 1The larger size of the specimen may also enable it to be usedas a mass loss coupon.6.3.3.3 The counter electrode is placed on the return path ofthe jet to avoid interference with the jet flow (Fig. 7).Reference electrode is placed in the si
36、de of the jet arm.6.3.3.4 This design uses multiple specimens (typically four)(Fig. 8). The jet is created in a central cell with four armscontaining four nozzles. The impeller is housed in the cell bodyand is driven by a motor magnetically coupled to the impellershaft. Fluid from the cell is forced
37、 by the impeller through thenozzles and is recirculated to the cell. All moving parts of thepump are located inside the central cell (7).6.4 For all designs, the relationship between the motorspeed that creates the jet and the flow rate shall be established.A procedure to establish such a relationsh
38、ip is described inAnnex A2.6.5 For atmospheric pressure experiment, an apparatus con-structed from acrylic, PFTE, or an inert material shall be used.For experiments above atmospheric pressure, an apparatus thatcan withstand high pressure without leakage must be used.Such high-temperature, high-press
39、ure jet impingement (HTH-PJI) system is constructed using corrosion-resistant alloy(CRA).6.6 For all designs, the apparatus must contain ports forspecimen, counter electrode, reference electrode, inlet andoutlet. Additional ports enable measurement of pH and tem-perature during the experiment and dr
40、aining of the test solutionafter the experiment. Both inlet and outlet ports should be fittedwith a Y joint, so that the apparatus is connected to both a gascylinder and the preparation apparatus. In Design 1 and 2, apump that creates the jet should be placed between thepreparation and experimental
41、apparatus. In Design 3, the pumpshould be placed inside the apparatus itself.6.7 The suggested components can be modified, simplified,or made more sophisticated to fit the needs of a particularinvestigation. The suggested apparatus is basic and the appa-ratus is limited only by the judgment and inge
42、nuity of theinvestigator.7. Preparation of Test Specimens7.1 Methods for preparing specimens for tests and forremoving specimens after the test are described in Practice G1.7.2 The specimen shall be made of the material (forexample, carbon steel) for which the inhibitor is being evalu-ated. Corrosio
43、n rates and inhibitor performance change byseveral orders of magnitude as surface roughness changes fromrough to fine. The surface roughness shall be kept the sameduring inhibitor screening and, if possible, the surface rough-ness of specimens used in the laboratory experiments shall beNOTE 1Figure
44、not to scale. Shaded area indicates the location of the specimen.FIG. 2 Schematic Diagram of Experimental Test Cell (Design 1)G208 124related to that of field pipe. The specimens shall be ground toa specified surface finish. The grinding shall produce a repro-ducible surface finish, with no rust dep
45、osits, pits, or deepscratches. All sharp edges on the specimen shall be ground. Allloose dirt particles shall be removed.7.3 The appropriate ring or disc specimen shall be machinedand snugly fitted into the PTFE sample holder or sample holdermade from any other appropriate material, with no gapbetwe
46、en the sample and the holder. If necessary, a very smallamount of epoxy should be used to fit the specimen into theholder. The presence of a gap will create crevice corrosion aswell as change the flow pattern. The end cap is screwed in orattached tightly so that only the disc or ring of known area i
47、sexposed to the solution. Electrical connection shall be providedat the back of the specimen through spring connections.7.4 The specimens shall be rinsed with distilled water;degreased by immersing in acetone or methanol or any othersuitable solvent; ultrasonically cleaned (typically for about 1min)
48、; and then dried by blowing air. The surface of thespecimens shall not be touched with bare hands. The specimenshall be weighed to the nearest 0.1 mg. The dimensions shall bemeasured to the nearest 1 mm and the surface area calculated.7.5 The specimen shall be placed into the experimentalapparatus w
49、ithin 1 h of preparing the surface and the lid of theapparatus closed immediately.7.5.1 Specimen to be treated with batch inhibitor shall beexposed to inhibitor containing oil phase for a certain amountof time (usually 30 min). 8.8 describes the preparation ofinhibitor containing oil phase. The specimen shall be removedand introduced into the experimental apparatus immediately.8. Preparation of Test Solution8.1 Test solution shall be prepared in a separate container(preparation apparatus). Ideally, all phases (oil and aqueous) oftest solution shall be obtained from the field
