1、Designation: D3230 09Standard 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 revision. A number i
2、n 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 Department of Defense.1. Scope*1.1 This test method covers the determination of the ap-proximate
3、 chloride (salts) concentration in crude oil. The rangeof concentration covered is 0 to 500 mg/kg or 0 to 150lb/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 chlorides, such as sodium,calcium, and magne
4、sium. 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 Acceptable concentration units are g/m3or PTB (lb/1000 bbl).1.4 This standard does not purport to add
5、ress all of thesafety concerns, 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. For specificwarning statements, see 7.3, 7.4, and 7.11.
6、2. Referenced Documents2.1 ASTM Standards:2D381 Test Method for Gum Content in Fuels by Jet Evapo-rationD1193 Specification for Reagent WaterD4928 Test Methods for Water in Crude Oils by Coulom-etric Karl Fischer TitrationD5002 Test Method for Density and Relative Density ofCrude Oils by Digital Den
7、sity 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-ganic chlorides may also be present.4. Summary of Test Method4.1 This test method measure
8、s 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 conductivematerial, in the crude oil. A homogenized test specimen isdissolved in a mixed alcohol
9、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 referenceto a calibration curve of current versus chloride concentrationof known mixtures. C
10、alibration 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 approximatechloride content of crude oils, a knowledge of which isimportant in deciding whether
11、 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 hasdetrimental effects on catalysts used in these units.5.3 This test method provides
12、a rapid and convenient meansof determining the approximate content of chlorides in crudeoil and is useful to crude oil processors.6. 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 elec
13、trodes suspended in a testbeaker containing a test solution. The apparatus shall becapable 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, af
14、ter comparison to internal calibration curves, of display-ing the resultant concentration.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved Oct. 1
15、, 2009. Published November 2009. Originallyapproved in 1973. Last previous edition approved in 2008 as D323008. DOI:10.1520/D3230-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume infor
16、mation, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Test BeakerSee Annex A1.6.3 Pipet, 10-mL (t
17、otal 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 the entire volume of the material iscontained in the
18、 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 10mL graduatedcylinder in place of the pipet to transfer the neutral oil (10.3)and crude oil sample (11.1) to ens
19、ure consistency. The currentprecision statements are based on the use of 10mLpipets 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 chemicals shall beused in all tests. Unless otherwise
20、indicated, it is intended thatall reagents shall conform to the specifications of theAmericanChemical Society, where such specifications are available.3Other grades may be used, provided it is first ascertained thatthe reagent is of sufficiently high purity to permit its usewithout lessening the acc
21、uracy 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 volumes of absolute methyl alcohol (anhydrous). Toeach litre o
22、f 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 at 125 V ac. High conductivity can be due toexcess water
23、 in the solvent and can indicate that the methyl alcohol usedis not anhydrous.7.4 Hexanes, Reagent Grade,(WarningExtremely flam-mable, harmful if inhaled.)NOTE 3Hexanes solvent is sometimes referred to or sold by othernames, such as petroleum naphtha, petroleum ether, ligroine, petroleumbenzin, and
24、industrial naphtha. One should confirm that it meets therequirements of 7.4.7.5 Calcium Chloride (CaCl2) Solution (10 g/L)Transfer1.006 0.01 g of CaCl2, or the equivalent weight of a hydratedsalt, into a 100-mL volumetric flask and dissolve in 25 mL ofwater. Dilute to the mark with mixed alcohol sol
25、vent.7.6 Magnesium Chloride (MgCl2) Solution (10 g/L)Transfer 1.00 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 alcohol solvent.7.7 Sodium Chloride (NaCl) Solution (10 g/L)Transfer1.00 6 0.01
26、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 40C and free ofadditive.7.9 Salts, Mixed Solution (Concentrated Solution)Combine 10
27、.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 oils. When the relative proportionsof calcium, magnesium, and sodium chlorides are kno
28、wn 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 flask, and dilute to the mark with mixedalcohol solvent.7.11 Xylene, reagent grade, m
29、inimum purity. (WarningFlammable. Vapor harmful.)8. Sampling8.1 Obtain a sample and test specimen in accordance withTest Methods D4928. Ensure that the sample is completelyhomogenized with a suitable mixer. See Annex A1 of TestMethods D4928 for suitable apparatus and proving.8.2 Samples of very visc
30、ous 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 sediment and areinhomogeneous by nature. The presence of water and sedim
31、entwill 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 Prepare the apparatus for operation in accordance withthe manufacturers i
32、nstructions for calibrating, checking, andoperating the equipment. (WarningThe voltage applied tothe electrodes can be as great as 250 V ac, and hazardous.)9.3 Thoroughly clean and dry all parts of the test beaker, theelectrodes, and its accessories before starting the test, beingsure to remove any
33、solvent that had been used to clean theapparatus.10. Calibration10.1 The conductivity of solutions is affected by the tem-perature of the specimen when measurements are made. Thetemperature of the test specimen at the time of measurementshall be within 3C of the temperature at which the calibrationc
34、urves were made.10.2 Establish a blank measurement by following the pro-cedure in 10.3 and 10.4, omitting the mixed salts solution.When the indicated electrode current is greater than 0.25 mAat3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For
35、 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), Rockville,MD.D3230 092125 V ac, water
36、 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 graduated, glass-stoppered mixingcylinder, add 15 mL of xylene. From a 10-mL
37、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. Stopper and shake the cylindervigorously for approximately 60 s to effect sol
38、ution. 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 vigorously for approximately 30 s to effectsolution, and allow the solution to stand a
39、pproximately 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. Adjust theindicated electrode voltage to a series of values, for example25,
40、50, 125, 200, and 250 V ac. At each voltage, note thecurrent reading and record the voltage displayed and thecurrent to the nearest 0.01 mA. Remove the electrodes from thesolution, rinse with xylene followed by naphtha, and allowthem to dry.NOTE 5With some apparatus, the detailed settings will not b
41、erequired since the electronics are built-in for auto-ranging. Determinationof the blank and the calibration standard responses are the same.10.5 Repeat the procedure in 10.3, using other volumes ofmixed salts solution (dilute solution) as needed to cover therange of chloride contents of interest.10
42、.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 voltage on 3 by 3 cyclelog-log paper, or other suitable format.NOTE 6Some apparatus are ca
43、pable of internally recording thecurrent readings, standard concentration, and blank, and they provide anoutput in direct concentration units.NOTE 7The apparatus are calibrated against standard solutions ofneutral oil and mixed chloride solutions in xylene because of the extremedifficulties in keepi
44、ng 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 in the extract.NOTE 8In calibrating over a wide range of chloride concentr
45、ations, itmay be necessary to apply several voltages to obtain current readingswithin the limit of the apparatus current level display (0 to 10 mA). Highervoltages are applied for low concentrations and lower voltages are appliedfor high concentrations.11. Procedure11.1 To a dry, 100-mL graduated, g
46、lass-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-stop
47、pered cylinder. Rinse the10-mL pipet or 10-mL graduated cylinder with xylene untilfree of oil. Make up to 50 mL with xylene. Stopper and shakethe cylinder vigorously for approximately 60 s. Dilute to 100mL with mixed alcohol solvent, and again shake vigorously forapproximately 30 s. After allowing t
48、he solution to stand forapproximately 5 min, pour it into the dry test beaker.11.2 Follow the procedure in 10.4 to obtain voltage andcurrent readings. Record the indicated electrode current to thenearest 0.01 mA and the nearest voltage.11.3 Remove the electrodes from the sample solution, andclean th
49、e apparatus.12. Calculation12.1 Subtract the value obtained for the blank measurementfrom the value obtained from the specimen measurement toobtain the net current reading. From the calibration graph, readthe indicated salt concentration corresponding to the netcurrent (mA) reading of the sample.12.2 Calculate the concentration in mg/kg by using theappropriate equation given below:Salt, mg/kg 51000Xd(1)Salt, mg/kg 5 2853 Y/d (2)where:X = measured salt concentration in g/m3,Y = measured salt concentration in PTB, andd = specimen density at 15 C in kg/m3.NO
