ASTM D7829-13
(Guide)Standard Guide for Sediment and Water Determination in Crude Oil
Standard Guide for Sediment and Water Determination in Crude Oil
SIGNIFICANCE AND USE
3.1 Theoretically, all of the sediment and water determination methods are valid for crude oils containing from 0 to 100 % by volume sediment and water; the range of application is specified within the scope of each method. The round robins for all methods were conducted on relatively dry oil. All precision and bias statements included in the methods are based upon the round robin data. Analysis becomes more challenging with crude oils containing higher water contents due to the difficulty in obtaining a representative sample, and maintaining the sample quality until analysis begins.
3.2 Currently, Karl Fischer is generally used for dry crude oils containing less than 5 % water. Distillation is most commonly used for dry and wet crude oils and where separate sediment analysis is available or in situations where the sediment result is not significant. The laboratory centrifuge methods allow for determination of total sediment and water in a single analysis. The field centrifuge method is used when access to controlled laboratory conditions are not available.
3.3 In the event of a dispute with regard to sediment and water content, contracting parties may refer to the technical specifications table to determine the most appropriate referee method based upon knowledge of and experience with the crude oil or product stream.
SCOPE
1.1 This guide covers a summary of the water and sediment determination methods from the API MPMS Chapter 10 for crude oils. The purpose of this guide is to provide a quick reference to these methodologies such that the reader can make the appropriate decision regarding which method to use based on the associated benefits, uses, drawbacks and limitations.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, 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.
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Designation: D7829 − 13
StandardGuide for
Sediment and Water Determination in Crude Oil
This standard is issued under the fixed designation D7829; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope Karl Fischer Titration
D5854 Practice for Mixing and Handling of Liquid Samples
1.1 This guide covers a summary of the water and sediment
of Petroleum and Petroleum Products (API MPMS Chap-
determination methods from the API MPMS Chapter 10 for
ter 8.3)
crude oils. The purpose of this guide is to provide a quick
2.2 API Standards:
reference to these methodologies such that the reader can make
API MPMS Chapter 8.1 Standard Practice for Manual Sam-
the appropriate decision regarding which method to use based
pling of Petroleum and Petroleum Products (ASTM
on the associated benefits, uses, drawbacks and limitations.
D4057)
1.2 The values stated in SI units are to be regarded as
API MPMS Chapter 8.2 Standard Practice for Automatic
standard. No other units of measurement are included in this
Sampling of Petroleum and Petroleum Products (ASTM
standard.
D4177)
1.3 This standard does not purport to address all of the
API MPMS Chapter 8.3 Standard Practice for Mixing and
safety concerns, if any, associated with its use. It is the
Handling of Liquid Samples of Petroleum and Petroleum
responsibility of the user of this standard to establish appro-
Products (ASTM D5854)
priate safety and health practices and determine the applica-
MPMS Chapter 10.1 Standard Test Method for Sediment in
bility of regulatory limitations prior to use. Crude Oils and Fuel Oils by the Extraction Method
(ASTM D473)
2. Referenced Documents
MPMS Chapter 10.2 Standard Test Method for Water in
Crude Oil by Distillation (ASTM D4006)
2.1 ASTM Standards:
MPMS Chapter 10.3 Standard Test Method for Water and
D473 Test Method for Sediment in Crude Oils and Fuel Oils
Sediment in Crude Oil by the Centrifuge Method (Labo-
by the Extraction Method (API MPMS Chapter 10.1)
ratory Procedure) (ASTM D4007)
D4006 Test Method for Water in Crude Oil by Distillation
MPMS Chapter 10.4 Determination of Water and/or Sedi-
(API MPMS Chapter 10.2)
ment in Crude Oil by the Centrifuge Method (Field
D4007 Test Method forWater and Sediment in Crude Oil by
Procedure)
the Centrifuge Method (Laboratory Procedure) (API
MPMS Chapter 10.7 Standard Test Method for Water in
MPMS Chapter 10.3)
Crude Oils by Potentiometric Karl Fischer Titration
D4057 Practice for Manual Sampling of Petroleum and
(D4377)
Petroleum Products (API MPMS Chapter 8.1)
MPMS Chapter 10.8 Standard Test Method for Sediment in
D4177 Practice for Automatic Sampling of Petroleum and
Crude Oil by Membrane Filtration (D4807)
Petroleum Products (API MPMS Chapter 8.2)
MPMS Chapter 10.9 Standard Test Method for Water in
D4377 Test Method forWater in Crude Oils by Potentiomet-
CrudeOilsbyCoulometricKarlFischerTitration(D4928)
ric Karl Fischer Titration
D4807 Test Method for Sediment in Crude Oil by Mem-
3. Significance and Use
brane Filtration
3.1 Theoretically, all of the sediment and water determina-
D4928 Test Method for Water in Crude Oils by Coulometric
tion methods are valid for crude oils containing from 0 to
100 % by volume sediment and water; the range of application
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
is specified within the scope of each method. The round robins
Products and Lubricants and is the direct responsibility of Subcommittee D02.02 on
for all methods were conducted on relatively dry oil. All
Hydrocarbon Measurement for Custody Transfer (Joint ASTM-API).
precision and bias statements included in the methods are
Current edition approved May 1, 2013. Published July 2013. DOI: 10.1520/
based upon the round robin data. Analysis becomes more
D7829-13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American Petroleum Institute (API), 1220 L. St., NW,
the ASTM website. Washington, DC 20005-4070, http://www.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7829 − 13
challenging with crude oils containing higher water contents that the resolution is appropriate, having sufficient significant
due to the difficulty in obtaining a representative sample, and figures, for the analysis.
maintaining the sample quality until analysis begins.
5. Report
3.2 Currently, Karl Fischer is generally used for dry crude
oils containing less than 5 % water. Distillation is most
Water Only Determination Methods
commonly used for dry and wet crude oils and where separate
5.1 MPMS Chapter 10.4, Determination of Water and/or
sediment analysis is available or in situations where the
Sediment in Crude Oil by the Centrifuge Method (Field
sediment result is not significant. The laboratory centrifuge
Procedure):
methods allow for determination of total sediment and water in
a single analysis. The field centrifuge method is used when
NOTE 1—ASTM Test Methods D96 for Water and Sediment in Crude
access to controlled laboratory conditions are not available. Oil By Centrifuge (Field Procedure), the technically equivalent ASTM
standard was withdrawn without replacement in 2000.
3.3 In the event of a dispute with regard to sediment and
5.1.1 Range of Application:
water content, contracting parties may refer to the technical
5.1.1.1 There is no approved precision and bias statement
specifications table to determine the most appropriate referee
for this method.
method based upon knowledge of and experience with the
5.1.1.2 The practical minimum detection limit is 0.025 %
crude oil or product stream.
v/v water. Lower concentrations of water should be reported as
less than 0.025 % v/v or 0 % v/v.
4. Procedure
5.1.1.3 This scope of the method indicates that it applies to
4.1 To obtain the total sediment and water results when the
crude oil, there is no water content specified in the scope.
two are determined by separate methods: First, add the raw,
5.1.2 Interferences, Biases, and Limitations:
unrounded results together, and then round the sum to the
5.1.2.1 The round robin for this method was conducted for
correct significant figure.
combined sediment and water, not the sediment or water
4.2 It is critically important that the analytical samples are
fractions separately. Therefore the precision and bias state-
collected and handled with careful regard to ensure that they
ments do not apply to analysis of water only.
are representative of the entire parcel. The crude oil or product
5.1.2.2 This method will typically quantify light alcohols
stream should be homogenous at the sampling point, and the
such as, (but not limited to), methanol and ethanol in the water
sample properly mixed prior to analysis. Sub-samples should
fraction, biasing the water result high.
not be allowed to settle prior to transfer into an analytical
5.1.2.3 Centrifuge tubes may be filled directly from a
device such as a centrifuge tube, distillation apparatus, or
sample tap and analyzed minimizing sample handling. Mini-
extraction thimble. Refer to API MPMS Chapter 8.1 (ASTM
mizing sample handling helps to maintain the representative
D4057) Standard Practice for Manual Sampling of Petroleum
nature of a sample.
and Petroleum Products, API MPMS Chapter 8.2 (ASTM
5.1.2.4 A50 mL sample is used for analysis as measured in
D4177) Standard Practice for Automatic Sampling of Petro-
the centrifuge tube.
leum and Petroleum Products, API MPMS, and Chapter 8.3
5.1.2.5 The variety of acceptable solvents allows the user to
(ASTM D5854) Standard Practice for Mixing and Handling of
match the best solvent to the crude type. This can minimize
Liquid Samples of Petroleum and Petroleum Products for
bias resulting from precipitated material (asphaltenes or paraf-
appropriate sample collection and mixing.
fins) being measured as sediment.
4.3 Itisimperativethateverysampleismixedsufficientlyto
5.1.2.6 This method will not measure dissolved water, thus
ensure that it is homogeneous. However, with prolonged
the results may be biased low in crudes with dissolved water.
mixing the temperature of the sample will increase. This will
In addition, depending upon the efficiency of the emulsion
decrease the representative nature of the sample due to
breaker used, some highly stable emulsions may not fully
evaporative losses. The mixing system must be evaluated to
break down which will bias the results low.
determine that the mixing time is sufficient without undue
5.1.2.7 The sensitivity of this method is limited to the
temperature increases.
divisions marked on centrifuge tubes.The intervals range from
0.025 % to 12.5 % by volume of sediment and water.
4.4 Sampling error can be a source of bias in analytical
5.1.2.8 The method is not highly prescriptive, and lack of
methods. This is reflected in the precision and bias statement
consistency may be a source of variability in the results.
for each method, but it should be considered when evaluating
5.1.2.9 Because the user reads the result directly off the
methods.Alarger sample size will increase the probability that
glassware, result interpretation is susceptible to human error.
asampleisrepresentativeoftheentireparcelandcanminimize
5.1.2.10 Because this method is often performed in an
the potential bias arising from a less homogenous sample
stream. Measuring sample size by weight using an analytical uncontrolled environment, maintaining “stoppered” tubes
throughout the entire analytical process may help maintain the
balance is not subject to human error; measuring sample size
by volume using analytical glassware is a source of human representative nature of the sample.
error.
5.2 MPMS Chapter 10.2 (ASTM D4006, IP 358/82), Stan-
dard Test Method for Water in Crude Oil by Distillation:
4.5 When sample size is determined by weight, consider the
type of analytical balance used to weigh the sample. Ensure 5.2.1 Range of Application:
D7829 − 13
5.2.1.1 The scope of this test method does not indicate a 5.3.2.4 Syringes of sample may be drawn directly from the
range of water content. The round robin, upon which the sample vessel of they may be drawn from a subsample
precisionandbiasstatementwasdeveloped,rangedfrom0.1% container. The syringe contents are then transferred to the
to 1 % water by volume. titration vessel. The use of a subsample container and the
syringe are a source of error.
5.2.1.2 Thepracticalminimumdetectionlimitis0.025%by
volume.Lowerconcentrationsofsedimentandwatershouldbe
5.3.2.5 The analytical sample size is 1 to5gof crude oil.
reported as less than 0.025 % v/v or 0 % v/v.
5.3.2.6 The resolution for this test method is in the nearest
5.2.2 Interferences, Biases, and Limitations:
hundredth 0.08 mass % for relatively dry crude up to the
5.2.2.1 This test method will typically quantify light alco-
nearest 0.4 mass % for wetter crude oils.
hols such as, but not limited to, methanol and ethanol in the
5.3.2.7 This repeatability for this test method ranges from
water fraction, biasing the water result high.
0.012 for 0.05 mass % of water to 0.040 mass % for 2.0 mass
5.2.2.2 Volumetric glassware may be filled directly from a
% of water.
sample tap. The volumetric glassware is rinsed with multiple
5.3.2.8 Due to the non-prescriptive flexibility in selection of
portions of solvent to ensure full transference of sample into
solvents and titration parameters, the potentiometric Karl
the distillation apparatus.This helps ensure that sample did not
Fischermethodmayhavegreaterinterferencefrommercaptans
settle prior to collection of analytical portions. If the sample is
than the coulometric method.
allowed to settle, the representative nature may be in question.
5.3.2.9 Samplesandaliquotsinsecondarycontainers,which
5.2.2.3 Samples used for analysis range from 5 to 200 g or
includes syringes, may stratify over time and bias the results.
mL, with the smaller sample used for crude oils containing a
5.3.2.10 This test method requires weighing the sample, but
higher water content.
does not include a balance as required equipment.
5.2.2.4 The sensitivity of this test method is limited to the
5.3.2.11 This test method allows manual titration using
divisions marked on the distillation trap. The intervals range
Karl-Fischer reagent. Because the user reads the result directly
from0.125 %to0.5 %waterbyvolume.Theintervalsincrease
off the glassware, result interpretation is susceptible to human
as the water content of the crude oil increases.
error.
5.2.2.5 The repeatability for this test method ranges from
5.3.2.12 Top loading balances must be calibrated and certi-
0.017 for 0.005 volume % of water to 0.08 for 0.130 volume %
fied regularly.
of water.
5.2.2.6 This test method is more time consuming than the
5.4 MPMS Chapter 10.9 (ASTM D4928-00, IP 386/99),
centrifuge or Karl Fischer methods.
Standard Test Method for Water in Crude Oils by Coulometric
5.2.2.7 This test method requires a laboratory environment
Karl Fischer Titration:
to set up and operate.
5.4.1 Range of Application:
5.2.2.8 Because the user reads the result directly off the
5.4.1.1 This procedure is applicable to the determination of
glassware, result interpretation is susceptible to human error.
water in crude oils containing from 0.02 % to 5 % water.
5.3 MPMS Chapter 10.7 (ASTM D4377-00, IP 356/99),
5.4.1.2 The practical minimum detection limit is 0.005 %.
Standard Test Method for Water in Crude Oils by Potentiomet-
Lower concentrations of sediment and water should be re-
ric Karl Fischer Titration:
ported as less than 0.005 % v/v or 0 % v/v.
5.3.1 Range of Application:
5.4.2 Interferences, Biases, and Limitations:
5.3.1.1 The scope of this test method applies to crude oils
5.4.2.1 This test method may be appropriate for crude oils
containing 0.02 to 2 mass or volume % of water.
and products which contain light alcohols such as, but not
5.3.1.2 The average practical minimum detection limit for
limited to, methanol and ethanol. However, no samples con-
this method is 0.08 mass %. This is based upon oil with a
taining alcohols were used in the round robin study; conse-
relative density of 0.850 and a water equivalence of 4 for the
quently the precision and bias statements in the method do not
titration.
apply.
5.3.2 Interferences, Biases, and Limitations:
5.4.2.2 The precision and bias sta
...
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