1、Designation: D3230 13 (Reapproved 2018)Standard Test Method forSalts in Crude Oil (Electrometric Method)1This standard is issued under the fixed designation D3230; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers the determinati
3、on of the ap-proximate chloride (salts) concentration in crude oil. The rangeof concentration covered is 0 mg kg to 500 mg kg or0 lb 1000 bbl to 150 lb 1000 bbl as chloride concentration/volume of crude oil.1.2 This test method measures conductivity in the crude oildue to the presence of common chlo
4、rides, such as sodium,calcium, and magnesium. Other conductive materials may alsobe present in the crude oil.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3.1 ExceptionAcceptable concentration units are g/m3or PTB (lb/10
5、00 bbl).1.4 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-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prio
6、r to use.For specific warning statements, see 7.3, 7.4, and 7.11.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-menda
7、tions issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D381 Test Method for Gum Content in Fuels by Jet Evapo-rationD1193 Specification for Reagent WaterD4928 Test Method for Water in Crude Oils by CoulometricKarl Fischer Ti
8、trationD5002 Test Method for Density and Relative Density ofCrude Oils by Digital Density Analyzer3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 PTBlb/1000 bbl.3.1.2 salts in crude oilcommonly, chlorides of sodium,calcium, and magnesium dissolved in crude oil. Other inor-gani
9、c chlorides may also be present.4. Summary of Test Method4.1 This test method measures the conductivity of a solutionof crude oil in a mixed alcohol solvent when subjected to anelectrical stress. This test method measures conductivity due tothe presence of inorganic chlorides, and other conductivema
10、terial, in the crude oil. A homogenized test specimen isdissolved in a mixed alcohol solvent and placed in a test cellconsisting of a beaker and a set of electrodes. A voltage isimpressed on the electrodes, and the resulting current flow ismeasured. The chloride (salt) content is obtained by referen
11、ceto a calibration curve of current versus chloride concentrationof known mixtures. Calibration curves are based on standardsprepared to approximate the type and concentration of chlo-rides in the crude oils being tested.5. Significance and Use5.1 This test method is used to determine the approximat
12、echloride content of crude oils, a knowledge of which isimportant in deciding whether or not the crude oil needsdesalting. The efficiency of the process desalter can also beevaluated.5.2 Excessive chloride left in the crude oil frequently resultsin higher corrosion rates in refining units and also h
13、asdetrimental effects on catalysts used in these units.5.3 This test method provides a rapid and convenient meansof determining the approximate content of chlorides in crudeoil and is useful to crude oil processors.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Product
14、s, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved July 1, 2018. Published August 2018. Originallyapproved in 1973. Last previous edition approved in 2013 as D3230 13. DOI:10.1520/D3230-13R18.2For referenced ASTM stan
15、dards, 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 Barr Harbor Drive, PO Box C700, West Conshohocken, P
16、A 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization
17、Technical Barriers to Trade (TBT) Committee.16. Apparatus6.1 The apparatus (see Annex A1) shall consist of a controlunit capable of producing and displaying several voltage levelsfor applying stress to a set of electrodes suspended in a testbeaker containing a test solution. The apparatus shall beca
18、pable of measuring and displaying the current (mA) con-ducted through the test solution between the electrodes at eachvoltage level.NOTE 1Some apparatus are capable of measuring voltage and currentinternally and, after comparison to internal calibration curves, of display-ing the resultant concentra
19、tion.6.2 Test BeakerSee Annex A1.6.3 Pipet, 10 mL (total delivery), shall be used in 10.3 and11.1 when the viscosity of the crude oil material beinganalyzed is suitable to transfer the required volume for use inthe test (see 6.3.1). The type of pipet to use is one that is ableto be rinsed to ensure
20、the entire volume of the material iscontained in the intended volume.6.3.1 In some cases, the viscosity of the crude oil makes itdifficult and impractical to transfer 10 mL of sample using apipet. In such cases, it is permissible to use a 10 mL graduatedcylinder in place of the pipet to transfer the
21、 neutral oil (10.3)and crude oil sample (11.1) to ensure consistency. The currentprecision statements are based on the use of 10 mL pipets only.6.4 Cylinders, 100 mL, stoppered.6.5 Other volumetric and graduated pipets and volumetricflasks.7. Reagents and Materials7.1 Purity of ReagentsReagent grade
22、 chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the AmericanChemical Society, where such specifications are available.3Other grades may be used, provided it is first ascertained thatthe reagent is of sufficientl
23、y high purity to permit its usewithout lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type II in Specification D1193.7.3 Mixed Alcohol SolventMix 63 volumes of 1-butanoland 37 volume
24、s of absolute methyl alcohol (anhydrous). Toeach litre of this mixture, add 3 mL of water. (WarningFlammable. Liquid causes eye burns. Vapor harmful. May befatal or cause blindness if swallowed or inhaled.)NOTE 2The mixed alcohol solvent is suitable for use if its conduc-tivity is less than 0.25 mA
25、at 125 V ac (or 2 microsiemens). Highconductivity can be due to excess water in the solvent and can indicate thatthe methyl alcohol used is not anhydrous.7.4 Hexanes, Reagent Grade, (WarningExtremelyflammable, harmful if inhaled.)NOTE 3Hexanes solvent is sometimes referred to or sold by othernames,
26、such as petroleum naphtha, petroleum ether, ligroine, petroleumbenzin, and industrial naphtha. One should confirm that it meets therequirements of 7.4.7.5 Calcium Chloride (CaCl2) Solution (10 g L)Transfer1.00 g 6 0.01 g of CaCl2, or the equivalent weight of ahydrated salt, into a 100 mL volumetric
27、flask and dissolve in25 mL of water. Dilute to the mark with mixed alcohol solvent.7.6 Magnesium Chloride (MgCl2) Solution (10 g L)Transfer 1.00 g 6 0.01 g of MgCl2, or the equivalent weight ofa hydrated salt, into 100 mL volumetric flask and dissolve in25 mL of water. Dilute to the mark with mixed
28、alcohol solvent.7.7 Sodium Chloride (NaCl) Solution (10 g L)Transfer1.00 g 6 0.01 g of NaCl into a 100 mL volumetric flask anddissolve in 25 mL of water. Dilute to the mark with mixedalcohol solvent.7.8 Oil, Refined NeutralAny refined chloride-free oil ofapproximately 20 mm2/sec (cSt) viscosity at 4
29、0 C and free ofadditive.7.9 Salts, Mixed Solution (Concentrated Solution)Combine 10.0 mL of the CaCl2solution, 20.0 mL of the MgCl2solution, and 70.0 mL of the NaCl solution, and mix thor-oughly.NOTE 4The 10:20:70 proportions are representative of the chloridespresent in a number of common crude oil
30、s. When the relative proportionsof calcium, magnesium, and sodium chlorides are known for a given crudeoil, such proportions should be used for most the accurate results.7.10 Salts, Mixed Solution (Dilute Solution)Transfer 10mL of the concentrated mixed chlorides solution into a1000 mL volumetric fl
31、ask, and dilute to the mark with mixedalcohol solvent.7.11 Xylene, reagent grade, minimum purity. (WarningFlammable. Vapor harmful.)8. Sampling8.1 Obtain a sample and test specimen in accordance withTest Method D4928. Ensure that the sample is completelyhomogenized with a suitable mixer. See Test Me
32、thod D4928for suitable apparatus and proving.8.2 Samples of very viscous materials may be warmed untilthey are reasonably fluid before they are sampled; however, nosample shall be heated more than is necessary to lower theviscosity to a manageable level.8.3 Samples of crude oil contain water and sed
33、iment and areinhomogeneous by nature. The presence of water and sedimentwill influence the conductivity of the sample. The utmost careshall be taken in obtaining homogenized representativesamples.9. Preparation of Apparatus9.1 Support the apparatus on a level, steady surface, such asa table.9.2 Prep
34、are the apparatus for operation in accordance withthe manufacturers instructions for calibrating, checking, andoperating the equipment. (WarningThe voltage applied tothe electrodes can be as great as 250 V ac, and hazardous.)3Reagent Chemicals, American Chemical Society Specifications, AmericanChemi
35、cal Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockv
36、ille,MD.D3230 13 (2018)29.3 Thoroughly clean and dry all parts of the test beaker, theelectrodes, and its accessories before starting the test, beingsure to remove any solvent that had been used to clean theapparatus.10. Calibration10.1 The conductivity of solutions is affected by the tem-perature o
37、f the specimen when measurements are made. Thetemperature of the test specimen at the time of measurementshall be within 3 C of the temperature at which the calibrationcurves were made.10.2 Establish a blank measurement by following the pro-cedure in 10.3 and 10.4, omitting the mixed salts solution.
38、When the indicated electrode current is greater than 0.25 mAat125 V ac, water or another conductive impurity is present andits source must be found and eliminated before calibration canbe completed. Determine a blank measurement each time freshxylene or mixed solvent is used.10.3 Into a dry, 100 mL
39、graduated, glass-stoppered mixingcylinder, add 15 mL of xylene. From a 10 mL pipet (totaldelivery, see 6.3), or 10 mL graduated cylinder (see 6.3.1)when applicable, add 10 mL of neutral oil. Rinse the 10 mLpipet or 10 mL graduated cylinder with xylene until free of oil.Make up to 50 mL with xylene.
40、Stopper and shake the cylindervigorously for approximately 60 s to effect solution. Add aquantity of dilute mixed salts solution, in accordance withTable 1, that is appropriate to the range of salt contents to bemeasured. Dilute to 100 mL with mixed alcohol solvent. Againshake the cylinder vigorousl
41、y for approximately 30 s to effectsolution, and allow the solution to stand approximately 5 min.Pour the solution into a dry test beaker.10.4 Immediately place the electrodes into the solution inthe beaker, making sure that the upper edge of the electrodeplates are below the surface of the solution.
42、 Adjust theindicated electrode voltage to a series of values, for example25 V, 50 V, 125 V, 200 V, and 250 V ac. At each voltage, notethe current reading and record the voltage displayed and thecurrent to the nearest 0.01 mA. Remove the electrodes from thesolution, rinse with xylene followed by naph
43、tha, and allowthem to dry.NOTE 5With some apparatus, the detailed settings will not be requiredsince the electronics are built-in for auto-ranging. Determination of theblank and the calibration standard responses are the same.10.5 Repeat the procedure in 10.3, using other volumes ofmixed salts solut
44、ion (dilute solution) as needed to cover therange of chloride contents of interest.10.6 Subtract the value obtained for the blank measurementfrom the indicated current readings of each standard sample,and plot the chloride content (ordinate) against net current(mA) readings (abscissa) for each volta
45、ge on 3 by 3 cyclelog-log paper, or other suitable format.NOTE 6Some apparatus are capable of internally recording the currentreadings, standard concentration, and blank, and they provide an output indirect concentration units. Alternatively, some apparatus are also capableof internally converting a
46、nd displaying the measured currents intoconductivity units of microsiemens, S, although the precision of suchinstruments was not evaluated in the 1997 interlaboratory study identifiedin Section 14, Precision and Bias.NOTE 7The apparatus are calibrated against standard solutions ofneutral oil and mix
47、ed chloride solutions in xylene because of the extremedifficulties in keeping crude oil-brine mixtures homogeneous. The cali-bration may be confirmed, if desired, by careful replicate analysis ofcrude-oil samples by exhaustive extraction of salts with hot water,followed by titration of the chlorides
48、 in the extract.NOTE 8In calibrating over a wide range of chloride concentrations, itmay be necessary to apply several voltages to obtain current readingswithin the limit of the apparatus current level display (0 mA to 10 mA).Higher voltages are applied for low concentrations and lower voltages area
49、pplied for high concentrations.11. Procedure11.1 To a dry, 100 mL graduated, glass-stoppered cylinder,add 15 mL of xylene and, using the same type of volumetransferring device used in 10.3 (that is, either a 10 mL pipet(total delivery, see 6.3), or 10 mL graduated cylinder (see6.3.1) when applicable), transfer 10 mL of the crude oil sampleinto the 100 mL graduated, glass-stoppered cylinder. Rinse the10 mL pipet or 10 mL graduated cylinder with xylene until freeof oil. Make up to 50 mL with xylene. Stopper and shake thecylinder vigorously for appro
