ASTM D3230-99
(Test Method)Standard Test Method for Salts in Crude Oil (Electrometric Method)
Standard Test Method for Salts in Crude Oil (Electrometric Method)
SCOPE
1.1 This test method covers the determination of salts in crude oil.
1.2 The accepted concentration units are pounds NaCl per 1000 bbl of crude oil.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 6.3, 6.4, and 6.11.
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An American National Standard
Designation: D 3230 – 99
Standard Test Method for
Salts in Crude Oil (Electrometric Method)
This standard is issued under the fixed designation D 3230; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Summary of Test Method
1.1 This test method covers the determination of the ap- 4.1 This test method measures the conductivity of a solution
proximate chloride (salts) concentration in crude oil. The range of crude oil in a mixed alcohol solvent when subjected to an
of concentration covered is 0 to 500 mg/kg or 0 to 150 lbs/1000 electrical stress. This test method measures conductivity due to
bbl as chloride concentration/volume of crude oil. the presence of inorganic chlorides, and other conductive
1.2 This test method measures conductivity in the crude oil material, in the crude oil. A homogenized test specimen is
due to the presence of common chlorides, such as sodium, dissolved in a mixed alcohol solvent and placed in a test cell
calcium, and magnesium. Other conductive materials may also consisting of a beaker and a set of electrodes. A voltage is
be present in the crude oil. impressed on the electrodes, and the resulting current flow is
1.3 The values stated in SI units are regarded as standard. measured. The chloride (salt) content is obtained by reference
Acceptable concentration units are g/m or PTB (lbs/1000 bbl). to a calibration curve of current versus chloride concentration
1.4 This standard does not purport to address all of the of known mixtures. Calibration curves are based on standards
safety concerns, if any, associated with its use. It is the prepared to approximate the type and concentration of chlo-
responsibility of the user of this standard to establish appro- rides in the crude oils being tested.
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitations prior to use. For specific
5.1 This test method is used to determine the approximate
precautionary statements, see 7.3, 7.4, and 7.11.
chloride content of crude oils, a knowledge of which is
2. Referenced Documents
important in deciding whether or not the crude oil needs
2.1 ASTM Standards: desalting. The efficiency of the process desalter can also be
D 91 Test Method for Precipitation Number of Lubricating evaluated.
Oils 5.2 Excessive chloride left in the crude oil frequently results
D 381 Test Method for Existent Gum in Fuels by Jet in higher corrosion rates in refining units and also has
Evaporation detrimental effects on catalysts used in these units.
D 1193 Specification for Reagent Water 5.3 This test method provides a rapid and convenient means
D 4928 Test Method for Water in Crude Oils by Coulom- of determining the approximate content of chlorides in crude
etric Karl Fischer Titration oil and is useful to crude oil processors.
D 5002 Test Method for Density and Relative Density of
4 6. Apparatus
Crude Oils by Digital Density Analyzer
6.1 The apparatus (see Annex A1) shall consist of a control
3. Terminology
unit capable of producing and displaying several voltage levels
3.1 Definitions of Terms Specific to This Standard: for applying stress to a set of electrodes suspended in a test
3.1.1 salts in crude oil—commonly, chlorides of sodium, beaker containing a test solution. The apparatus shall be
calcium, and magnesium dissolved in crude oil. Other inor- capable of measuring and displaying the current (mA) con-
ganic chlorides may also be present. ducted through the test solution between the electrodes at each
3.1.2 PTB—lbs/1000 bbl voltage level.
NOTE 1—Some apparatus are capable of measuring voltage and current
internally and, after comparison to internal calibration curves, of display-
This test method is under the jurisdiction of ASTM Committee D-2 on
ing the resultant concentration.
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
D02.03on Elemental Analysis.
6.2 Test Beaker—See Annex A1.
Current edition approved Nov. 10, 1999. Published January 2000. Originally
6.3 Pipet, 10 mL (total delivery)—The type of pipet that is
published as D 3230 – 73. Last previous edition D 3230 – 97.
rinsed to ensure the entire volume of the material is contained
Annual Book of ASTM Standards, Vol 05.01.
Annual Book of ASTM Standards, Vol 11.01.
in the intended volume.
Annual Book of ASTM Standards, Vol 05.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3230–99
6.4 Cylinders, 100 mL, stoppered. 7.10 Salts, Mixed Solution (Dilute Solution)—Transfer 10
6.5 Other volumetric and graduated pipets and volumetric mL of the concentrated mixed chlorides solution into a
1000-mL volumetric flask, and dilute to the mark with mixed
flasks.
alcohol solvent.
7.11 Xylene, reagent grade, minimum purity. (Warning—
7. Reagents and Materials
Flammable. Vapor harmful.)
7.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
8. Sampling
all reagents shall conform to the specifications of the American
8.1 Obtain a sample and test specimen in accordance with
Chemical Society, where such specifications are available.
Test Method D 4928. Ensure that the sample is completely
Other grades may be used, provided it is first ascertained that
homogenized with a suitable mixer. See Annex A1 of Test
the reagent is of sufficiently high purity to permit its use
Method D 4928 for suitable apparatus and proving.
without lessening the accuracy of the determination.
8.2 Samples of very viscous materials may be warmed until
7.2 Purity of Water—Unless otherwise indicated, references
they are reasonably fluid before they are sampled; however, no
to water shall be understood to mean reagent water as defined
sample shall be heated more than is necessary to lower the
by Type II in Specification D 1193.
viscosity to a manageable level.
7.3 Mixed Alcohol Solvent—Mix 63 volumes of 1-butanol
8.3 Samples of crude oil contain water and sediment and are
and 37 volumes of absolute methyl alcohol (anhydrous). To
inhomogeneous by nature. The presence of water and sediment
each litre of this mixture, add 3 mL of water. (Warning—
will influence the conductivity of the sample. The utmost care
Flammable. Liquid causes eye burns. Vapor harmful. May be
shall be taken in obtaining homogenized representative
fatal or cause blindness if swallowed or inhaled.)
samples.
NOTE 2—The 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 to
9. Preparation of Apparatus
excess water in the solvent and can indicate that the methyl alcohol used
is not anhydrous.
9.1 Support the apparatus on a level, steady surface, such as
a table.
7.4 ASTM Precipitation Naphtha, conforming to the re-
9.2 Prepare the apparatus for operation in accordance with
quirements of Test Method D 91. (Warning—Extremely
the manufacturer’s instructions for calibrating, checking, and
Flammable. Harmful if inhaled. Vapors may cause flash fire.)
operating the equipment. (Warning—The voltage applied to
7.5 Calcium Chloride (CaCl ) Solution (10 g/L)—Transfer
the electrodes can be as great as 250 V ac, and hazardous.)
1.006 0.01 g of CaCl , or the equivalent weight of a hydrated
9.3 Thoroughly clean and dry all parts of the test beaker, the
salt, into a 100-mL volumetric flask and dissolve in 25 mL of
electrodes, and its accessories before starting the test, being
water. Dilute to the mark with mixed alcohol solvent.
sure to remove any solvent that had been used to clean the
7.6 Magnesium Chloride (MgCl ) Solution (10 g/L)—
apparatus.
Transfer 1.00 6 0.01 g of MgCl , or the equivalent weight of
a hydrated salt, into 100-mL volumetric flask and dissolve in
10. Calibration
25 mL of water. Dilute to the mark with mixed alcohol solvent.
10.1 The conductivity of solutions is affected by the tem-
7.7 Sodium Chloride (NaCl) Solution (10 g/L)—Transfer
perature of the specimen when measurements are made. The
1.00 6 0.01 g of NaCl into a 100-mL volumetric flask and
temperature of the test specimen at the time of measurement
dissolve in 25 mL of water. Dilute to the mark with mixed
shall be within 3°C of the temperature at which the calibration
alcohol solvent.
curves were made.
7.8 Oil, Refined Neutral—Any refined chloride-free oil of
10.2 Establish a blank measurement by following the pro-
approximately 20 mm /sec (cSt) viscosity at 40°C and free of
cedure in 10.3 and 10.4, omitting the mixed salts solution.
additive.
When the indicated electrode current is greater than 0.25 mA at
7.9 Salts, Mixed Solution (Concentrated Solution)—
125 V ac, water or another conductive impurity is present and
Combine 10.0 mL of the CaCl solution, 20.0 mL of the MgCl
2 2
its source must be found and eliminated before calibration can
solution, and 70.0 mL of the NaCl solution, and mix thor-
be completed. Determine a blank measurement each time fresh
oughly.
xylene or mixed solvent is used.
NOTE 3—The 10:20:70 proportions are representative of the chlorides
10.3 Into a dry, 100-mL graduated, glass-stoppered mixing
present in a number of common crude oils. When the relative proportions
cylinder, add 15 mL of xylene. From a pipet (total delivery),
of calcium, magnesium, and sodium chlorides are known for a given crude
add 10 mL of neutral oil. Rinse the pipet with xylene until free
oil, such proportions should be used for most the accurate results.
of oil. Make up to 50 mL with xylene. Stopper and shake the
cylinder vigorously for approximately 60 s to effect solution.
Add a quantity of dilute mixed salts solution, in accordance
with Table 1, that is appropriate to the range of salt contents to
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, D.C. For suggestions on the testing of reagents not
be measured. Dilute to 100 mL with mixed alcohol solvent.
listed by the American Chemical Society, see Analar Standards for Laboratory
Again shake the cylinder vigorously for approximately 30 s to
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
effect solution, and allow the solution to stand approximately 5
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. min. Pour the solution into a dry test beaker.
D3230–99
TABLE 1 Standard Samples
mately 30 s. After allowing the solution to stand for approxi-
Salt Salt Mixed Salts mately 5 min, pour it into the dry test beaker.
g/m lbs/1000 bbl Solution (dilute),
11.2 Follow the procedure in 10.4 to obtain voltage and
of Crude Oil of Crude Oil mL
current readings. Record the
...
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