ASTM D7060-20

Standard Test Method for Determination of the Maximum Flocculation Ratio and Peptizing Power in Residual and Heavy Fuel Oils (Optical Detection Method)

SIGNIFICANCE AND USE
5.1 Asphaltenes are naturally occurring materials in crude petroleum and petroleum products containing residual material. The asphaltenes are usually present in colloidal suspensions, but they may agglomerate and flocculate if the suspension of asphaltene molecules is disturbed through excess stress or incompatibility. This test method provides compatibility parameters, which can be used to assess stability reserve and compatibility.  
5.2 A blend is considered stable when the blend’s peptizing power is higher than the blend’s maximum flocculation ratio;3,4 both of them can be calculated using empirical blend rules. Refineries and terminal owners can prevent the flocculation of asphaltenes due to incompatibility by assessing the compatibility of fuels beforehand.
Note 4: See Appendix X1 for an example of prediction of compatibility.
SCOPE
1.1 This test method covers a procedure for quantifying the maximum flocculation ratio of the asphaltenes in the oil and the peptizing power of the oil medium, by an automatic instrument using an optical device.  
1.2 This test method is applicable to atmospheric or vacuum distillation residues, thermally cracked residue, intermediate and finished residual fuel oils, containing at least 1 % by mass asphaltenes. This test method has not been developed for asphalts.
Note 1: An optical probe detects the formation of flocculated asphaltenes. The start of flocculation is interpreted when a significant and sustained increase in rate-of-change of signal, as measured by the optical probe, ensures flocculation is in progress. The start of flocculation can be detected unambiguously when the sample contains at least 1 % mass asphaltenes as measured by Test Method D6560.
Note 2: This test method is applicable to products typical of Specification D396—Grades 5L, 5H, and 6, and Specification D2880—Grades 3-GT and 4-GT.  
1.3 This test method was evaluated in an interlaboratory study in the nominal range of 32 to 76 for the maximum flocculation ratio and in the nominal range of 36 to 95 for peptizing power.
Note 3: The nominal range is determined by (min. sample mean—Reproducibility) to (max. sample mean + Reproducibility).  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2020
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.14 - Stability, Cleanliness and Compatibility of Liquid Fuels

Relations

• Replaces: ASTM D7060-12(2019) - Standard Test Method for Determination of the Maximum Flocculation Ratio and Peptizing Power in Residual and Heavy Fuel Oils (Optical Detection Method)
• Effective Date: 01-May-2020
• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D6792-23c - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Nov-2023
• Refers: ASTM D6792-23b - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Oct-2023
• Refers: ASTM D396-19a - Standard Specification for Fuel Oils
• Effective Date: 15-Dec-2019
• Refers: ASTM D6300-19a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2019
• Refers: ASTM D396-19 - Standard Specification for Fuel Oils
• Effective Date: 01-May-2019
• Refers: ASTM D2880-18a - Standard Specification for Gas Turbine Fuel Oils
• Effective Date: 01-Oct-2018
• Refers: ASTM D396-18a - Standard Specification for Fuel Oils
• Effective Date: 01-Oct-2018
• Refers: ASTM D2880-18 - Standard Specification for Gas Turbine Fuel Oils
• Effective Date: 01-May-2018
• Refers: ASTM D396-18 - Standard Specification for Fuel Oils
• Effective Date: 01-May-2018
• Refers: ASTM D396-17a - Standard Specification for Fuel Oils
• Effective Date: 01-Dec-2017
• Refers: ASTM D396-17 - Standard Specification for Fuel Oils
• Effective Date: 01-Jul-2017
• Refers: ASTM D396-16 - Standard Specification for Fuel Oils
• Effective Date: 01-Oct-2016

Overview

ASTM D7060-20 is the standard test method developed by ASTM International for quantifying the maximum flocculation ratio and peptizing power in residual and heavy fuel oils using an optical detection method. This procedure is essential for evaluating fuel oil stability by providing key compatibility parameters, helping refineries, fuel terminals, and related industries prevent operational issues caused by asphaltene flocculation.

The test is specifically applicable to atmospheric or vacuum distillation residues, thermally cracked residues, intermediate and finished residual fuel oils that contain at least 1% by mass asphaltenes. The method is not intended for asphalts.

Key Topics

• Asphaltenes and Stability: Asphaltenes are naturally occurring materials in crude petroleum and residual fuels, typically present in colloidal suspension. Assessing their stability is crucial because agglomeration and flocculation can lead to phase separation and sedimentation, negatively impacting fuel handling and combustion.

• Flocculation Ratio and Peptizing Power:

  • Maximum flocculation ratio refers to the minimum solvency power (expressed as % 1-methylnaphthalene by volume) required to keep asphaltenes colloidally dispersed.
  • Peptizing power measures the actual solvency power, also as a percentage by volume, available within the oil medium to keep asphaltenes stable.

• Test Method Procedure:

  • Utilizes an integrated automated analytical system combining a titration unit, computer controls, and an optical probe.
  • Multiple solutions of the oil are titrated with cetane, and flocculation is detected optically as a significant change in signal rate.
  • Calculations are performed to determine the maximum flocculation ratio and peptizing power, which are used to assess compatibility and stability.

• Assessment Criteria: A blend is considered stable when its peptizing power exceeds its maximum flocculation ratio. These values can be calculated for blend predictions according to empirical blend rules.

Applications

The ASTM D7060-20 standard test method is widely used in:

• Oil Refineries and Blending Operations:

  • Ensuring compatible blending of different fuel streams to mitigate risk of asphaltene precipitation, which can cause filter plugging and storage tank issues.
  • Supporting decision-making for blending heavy fuel oils and residuals (such as those defined under ASTM D396 and D2880).

• Fuel Oil Testing Laboratories:

  • Routine quality control to monitor product stability and compatibility prior to shipment or blending.
  • Troubleshooting instability in marine and power generation fuel oil markets.

• Terminal and Storage Operators:

  • Evaluating storage tank compatibility, especially after adding new product or changing suppliers.

• Research and Development:

  • Studying fuel oil behavior and optimization for improved fuel stability and performance.

Understanding the flocculation ratio and peptizing power provides actionable insight for fuel blending, preventing operational disruptions, and optimizing fuel system performance.

Related Standards

• ASTM D396 - Specification for Fuel Oils
• ASTM D2880 - Specification for Gas Turbine Fuel Oils
• ASTM D4057 - Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4177 - Practice for Automatic Sampling of Petroleum and Petroleum Products
• ASTM D4870 - Test Method for Determination of Total Sediment in Residual Fuels
• ASTM D6560 - Test Method for Determination of Asphaltenes (Heptane Insolubles)
• ASTM D6300 - Practice for Determination of Precision and Bias in Test Methods
• ASTM D6792 - Practice for Quality Management Systems in Petroleum Products Testing

Practical Value

Applying ASTM D7060-20 provides measurable benefits through:

• Improved fuel compatibility assessments
• Reduced risk of fuel instability and operational downtime
• Data-driven blending decisions
• Enhanced product quality and regulatory compliance

This standard helps stakeholders in the petroleum industry ensure reliable, compatible, and stable fuel oils through scientifically validated test procedures and results.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7060 − 20
Standard Test Method for
Determination of the Maximum Flocculation Ratio and
Peptizing Power in Residual and Heavy Fuel Oils (Optical
Detection Method)
This standard is issued under the fixed designation D7060; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 This test method covers a procedure for quantifying the
mendations issued by the World Trade Organization Technical
maximumflocculationratiooftheasphaltenesintheoilandthe
Barriers to Trade (TBT) Committee.
peptizingpoweroftheoilmedium,byanautomaticinstrument
using an optical device.
2. Referenced Documents
1.2 Thistestmethodisapplicabletoatmosphericorvacuum
2.1 ASTM Standards:
distillation residues, thermally cracked residue, intermediate
D396Specification for Fuel Oils
and finished residual fuel oils, containing at least 1% by mass
D2880Specification for Gas Turbine Fuel Oils
asphaltenes. This test method has not been developed for
D4057Practice for Manual Sampling of Petroleum and
asphalts.
Petroleum Products
NOTE 1—An optical probe detects the formation of flocculated as-
D4177Practice for Automatic Sampling of Petroleum and
phaltenes. The start of flocculation is interpreted when a significant and
Petroleum Products
sustained increase in rate-of-change of signal, as measured by the optical
probe, ensures flocculation is in progress. The start of flocculation can be
D4870Test Method for Determination of Total Sediment in
detected unambiguously when the sample contains at least 1% mass
Residual Fuels
asphaltenes as measured by Test Method D6560.
D6300Practice for Determination of Precision and Bias
NOTE 2—This test method is applicable to products typical of Specifi-
Data for Use in Test Methods for Petroleum Products,
cation D396—Grades 5L, 5H, and 6, and Specification D2880—Grades
Liquid Fuels, and Lubricants
3-GT and 4-GT.
D6560Test Method for Determination ofAsphaltenes (Hep-
1.3 This test method was evaluated in an interlaboratory
tane Insolubles) in Crude Petroleum and Petroleum Prod-
study in the nominal range of 32 to 76 for the maximum
ucts
flocculation ratio and in the nominal range of 36 to 95 for
D6792Practice for Quality Management Systems in Petro-
peptizing power.
leum Products, Liquid Fuels, and Lubricants Testing
NOTE 3—The nominal range is determined by (min. sample mean—
Laboratories
Reproducibility) to (max. sample mean + Reproducibility).
3. Terminology
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3.1 Definitions:
standard.
3.1.1 asphaltenes, n—(rarely used in the singular), in petro-
1.5 This standard does not purport to address all of the leum technology, represent an oil fraction that is soluble in a
safety concerns, if any, associated with its use. It is the specified aromatic solvent but separates upon addition of an
responsibility of the user of this standard to establish appro- excess of a specified paraffinic solvent.
priate safety, health, and environmental practices and deter- 3.1.1.1 Discussion—In this test method, the aromatic sol-
mine the applicability of regulatory limitations prior to use. vent is 1-methylnapthalene, and the paraffinic solvent is
1.6 This international standard was developed in accor- n-hexadecane.
dance with internationally recognized principles on standard-
3.1.2 compatibility, n— of crude oils or of heavy fuel oils,
the ability of two or more crude oils or fuel oils to blend
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.14 on Stability, Cleanliness and Compatibility of Liquid Fuels. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2020. Published June 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2004. Last previous edition approved in 2019 as D7060–12 (2019). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7060-20. the ASTM website.
*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
D7060 − 20
together within certain concentration ranges without evidence 3.2.7.1 Discussion—For purposes of this test method, an oil
of separation, such as the formation of multiple phases. sample is considered to be composed of an oil medium
3.1.2.1 Discussion—Incompatible heavy fuel oils or crude (sometimes called an oil matrix or maltenes) and asphaltenes.
oils, when mixed or blended, result in the flocculation or
3.2.8 peptizing power, n—available solvency power, ex-
precipitation of asphaltenes. Some oils may be compatible
pressed as percentage by volume of 1-methylnaphthalene in a
within certain concentration ranges in specific mixtures, but
mixture of 1-methylnaphthalene and cetane, to keep as-
incompatible outside those ranges.
phaltenes in a colloidal solution.
3.1.3 flocculation, n— of asphaltenes from crude oils or
3.2.9 reciprocal dilution, n—dilution ratio of sample in
heavy fuel oils, the aggregation of colloidally dispersed as-
solvent mixture of 1-methylnaphthalene and cetane.
phaltenes into visibly larger masses which may or may not
3.3 Symbols:
settle.
FR = maximum flocculation ratio
3.1.4 peptization, n— of asphaltenes in crude oils or heavy
max
FR = flocculation ratio at critical dilution
fuel oils, the dispersion of asphaltenes to produce a colloidal
x
Po = peptizing power
dispersion.
Xmin = critical cetane dilution
3.1.5 stability reserve, n— of crude oils, heavy fuel oils, and
Xc = critical dilution
residual streams containing asphaltenes, the property of an oil
4. Summary of Test Method
to maintain asphaltenes in a peptized (colloidally dispersed)
state and prevent flocculation of the asphaltenes.
4.1 Six portions of the sample are diluted in various ratios
3.1.5.1 Discussion—An oil with a low stability reserve is
with 1-methylnaphthalene. Each solution is inserted into the
likelytoundergoflocculationofasphalteneswhenstressed(for
automatic apparatus, and titrated with cetane until flocculation
example, extended heated storage) or blended with a range of
of asphaltenes is detected by the optical probe. The first two
otheroils.Twooilseachwithahighstabilityreservearelikely
solutions are titrated with cetane in coarse determinations in
to maintain asphaltenes in a peptized state and not lead to
which the flocculation ratio is decreased in 5% steps. The
flocculation when blended together.
coarse determinations help to establish suitable starting values
for the fine determinations, in which the flocculation ratio is
3.2 Definitions of Terms Specific to This Standard:
decreased in 1% steps. The four flocculation ratios at critical
3.2.1 critical cetane dilution, n—number of millilitres of
dilution, measured during the fine determinations, are used to
cetane with which1gof undiluted sample can be diluted until
calculate the maximum flocculation ratio of the sample’s
it just does not flocculate the asphaltenes.
asphaltenes and the peptizing power of the sample’s oil
3.2.2 critical dilution, n—number of millilitres of
medium.
1-methylnaphthalene and cetane with which1gof undiluted
sample can be diluted until it just does not flocculate the
5. Significance and Use
asphaltenes.
5.1 Asphaltenes are naturally occurring materials in crude
3.2.2.1 Discussion—The number of millilitres of
petroleum and petroleum products containing residual mate-
1-methylnaphthaleneandcetaneisvariableanddependsonthe
rial. The asphaltenes are usually present in colloidal
ratioofsampleto1-methylnaphthaleneatthestartingpointand
suspensions, but they may agglomerate and flocculate if the
the sample type.
suspensionofasphaltenemoleculesisdisturbedthroughexcess
3.2.3 flocculation ratio, n—percentage by volume of
stress or incompatibility. This test method provides compat-
1-methylnaphtalene in a mixture of 1-methylnaphthalene and
ibilityparameters,whichcanbeusedtoassessstabilityreserve
cetane.
and compatibility.
3.2.4 flocculationratioatcriticaldilution,n—percentageby
5.2 Ablend is considered stable when the blend’s peptizing
3,4
volume of 1-methylnaphthalene in a mixture of
powerishigherthantheblend’smaximumflocculationratio;
1-methylnaphthalene and cetane at the inflection point.
both of them can be calculated using empirical blend rules.
Refineries and terminal owners can prevent the flocculation of
3.2.5 inflection point, n—last step during the titration with
asphaltenesduetoincompatibilitybyassessingthecompatibil-
cetane,whereflocculationofasphaltenesis notdetectedbythe
ity of fuels beforehand.
optical probe as a significant and sustained increase in rate-of-
NOTE 4—See Appendix X1 for an example of prediction of compat-
change of signal.
ibility.
3.2.6 maximum flocculation ratio, n—of asphaltenes, mini-
6. Interferences
mum required solvency power, expressed as percentage by
volume of 1-methylnaphthalene in a mixture of 6.1 High content of insoluble inorganic matter (sediment)
has some interference in this test method. In this case, the
1-methylnaphthalene and cetane, to keep the asphaltenes in a
colloidal solution. insoluble matter shall be removed by filtration according to
Test Method D4870.
3.2.6.1 Discussion—Maximumflocculationratioisthefloc-
culation ratio at extrapolated infinite dilution of the sample.
Berryman, T. J., and Lewis, C. P. G., “The Stability of Residual Fuels. Theory
3.2.7 oil medium, n—that portion of a sample of heavy fuel
and Practice of the Shell Concept,” 16th CIMAC Conference, Oslo, 1985.
oil or crude oil that surrounds and colloidally disperses the
Berg van den, F. G. A., “Developments in Fuel Oil Blending,” IASH 7th
asphaltenes. International Conference, Graz,Austria, 2000.
D7060 − 20
6.2 The presence of wax, present in paraffinic crudes or 7.4 Magnetic Stirrer/Hotplate, thermostatically controlled.
fuels from such crudes, does not interfere.
7.5 Stirring Bar, magnetic, PFTE-coated, 25 mm in length.
7. Apparatus
8. Reagents and Materials
7.1 Integrated Automated Analytical Measurement
8.1 Purity of Reagents—Reagent grade chemicals shall be
System—This test method uses an integrated automated ana-
used in all tests. Unless otherwise indicated, it is intended that
lytical measurement system comprised of a PC–based com-
all reagents conform to the specifications of the Committee on
puter and two titration stations (Fig. 1). See Annex A1 for
Analytical Reagents of theAmerican Chemical Society where
detailed information.
such specifications are available. Other grades may be used,
7.2 The computer controls test sequencing, acquires and
provided it is first ascertained that the reagent is of sufficiently
accumulates optical probe signal data, provides processing
high purity to permit its use without lessening the accuracy of
calculations, and automatically produces a report of important
the determination.
test parameters. The computer is capable of controlling one or
two independent titration stations. 8.2 Asphaltene Solution (3 g/L)—Dissolve 0.15 g of dry
asphaltenes in 1-methylnaphthalene and dilute to 50 mL. A
7.3 Each titration station consists of the following:
procedure to obtain asphaltenes is described in Appendix X2.
7.3.1 Automatic titration unit,
Prepare fresh daily, as needed.
7.3.2 Heater,
7.3.3 Magnetic stirrer,
8.3 Cetane (n-Hexadecane). (Warning—Irritating to respi-
7.3.4 Optical probe, and ratory system and skin.)
7.3.5 Reaction cell plus lid.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
The sole source of supply of the apparatus known to the committee at this time
Standard-Grade Reference Materials, American Chemical Society, Washington,
isAutomatedStabilityAnalyser,(UserManual,Version2),availablefromZematra,
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
3194 DG Hoogvliet, The Netherlands. If you are aware of alternative suppliers,
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
please provide this information to ASTM International Headquarters. Your com-
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
ments will receive careful consideration at a meeting of the responsible technical
copeial Convention, Inc. (USPC), Rockville, MD.
committee, which you may attend.
FIG. 1 Titration Stations of Integrated Automated Analytical Measurement System
D7060 − 20
8.4 Cleaning Solvent, technical grade, 95% purity, for and switch on the magnetic stirrer. Allow the specimen to
cleaning. It consists of one of the following: warm up, until its viscosity is low enough to obtain a smooth
8.4.1 Tetrahydrofuran, stabilized. (Warning—Extremely stirring performance.
flammable. Irritating to eyes and respiratory system.) 9.2.3.2 Add, according to Table 1, while continuously
8.4.2 Toluene. (Warning—Flammable. Health Hazard.)
stirring, an appropriate volume of 1-methylnaphthalene to the
8.4.3 Xylene. (Warning—Flammable. Harmful by inhala- nearest 0.01 mL.
tion and in contact with skin. Irritating to skin.)
9.2.3.3 Put the lid in place. Initiate the test procedure (12.3)
within 10 min.
8.5 n-Heptane.(Warning—Flammable.Vaporharmful.Va-
por may cause flash fire.)
NOTE 6—Never use excessive force when placing the lid in place.
8.6 1-Methylnaphthalene. (Warning—Harmful if swal-
10. Preparation of Apparatus
lowed. Irritating to skin.)
10.1 Prepare the instrument for operation in accordance
8.7 Quality Control (QC) Sample, a stable and homoge-
with the manufacturer’s instructions.
neousresidualfueloil.TheQCsamplecontainsatleast1%by
mass asphaltenes and has approximate viscosities in the range
10.2 Inspecttheopticalprobe’sglasssurfaceforcleanliness
2 2
of 180mm to 380mm /s at 50°C.
and damage before use. Connect the optical probes to the
respective apparatus’titration station. Place the optical probes
9. Sampling and Test Specimens
in the holder at the back of the corresponding titration station.
9.1 Sampling:
10.3 CleaningInstructions—Performthefollowingcleaning
9.1.1 ObtainsamplesinaccordancewithPracticesD4057or
procedure after the test procedure (see 12.3).
D4177.
10.3.1 Removethedosingtube.Cleanthetubewithaclean,
9.1.2 Samples of very viscous materials may be warmed
lintless cloth. Place the tube into its storage place.
until they are reasonably fluid before they are sampled.
10.3.2 Carefullyremovetheopticalsensorfromthereaction
9.1.3 Store samples prior to taking test specimens at ambi-
cell. (Warning—The hot sensor and reaction cell can cause
ent temperatures.
severe burns.) Clean the optical sensor with a clean, lintless
9.2 Test Specimen Preparation:
soft cloth using an appropriate solvent (see 8.4). Place the
9.2.1 Sample Fuel Temperature—Warm viscous samples
sensor in the holder on top of the reaction cell heater.
until they can be mixed readily before opening the storage
10.3.3 Take the reaction cell from the heater using wooden
container. For fuels with a high wax content (high pour point)
clamps, or use other protective measures to prevent burns.
the temperature shall be at least 15°C above the pour point.
10.3.4 Remove the lid. Remove the stirrer bar. Empty the
9.2.2 Shake or mix the sample thoroughly. If the sample
reaction cell.
contains a high content of insoluble matter, filter the sample
NOTE 7—A small silicon or rubber tube with an attached magnetic
through a 47mm diameter glass fiber filter medium (such as
stirrer is a handy tool to remove the stirrer bar from the reaction cell.
WhatmanGradeGF/A)usingtheTestMethodD4870filtration
Otherwise, the liquid can be poured over a metal sieve.
apparatus.
10.3.5 Cleanthereactioncellandstirrerwithanappropriate
9.2.3 Preparation of Six Specimen Blends—Visually check
solvent (see 8.4). Use a clean, lintless cloth to remove any
the reaction cell and the lid for cleanliness. Dissolve specimen
deposits.
in 1-methylnaphthalene in several different ratios of solvent
according to Table 1. Prepare the blends shortly before the test
11. Performance Check and QC
procedure. Generally follow the sequence: (1) prepare and test
Blend
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7060 − 12 (Reapproved 2019) D7060 − 20
Standard Test Method for
Determination of the Maximum Flocculation Ratio and
Peptizing Power in Residual and Heavy Fuel Oils (Optical
Detection Method)
This standard is issued under the fixed designation D7060; 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 Scope*
1.1 This test method covers a procedure for quantifying the maximum flocculation ratio of the asphaltenes in the oil and the
peptizing power of the oil medium, by an automatic instrument using an optical device.
1.2 This test method is applicable to atmospheric or vacuum distillation residues, thermally cracked residue, intermediate and
finished residual fuel oils, containing at least 1 % by mass asphaltenes. This test method has not been developed for asphalts.
NOTE 1—An optical probe detects the formation of flocculated asphaltenes. The start of flocculation is interpreted when a significant and sustained
increase in rate-of-change of signal, as measured by the optical probe, ensures flocculation is in progress. The start of flocculation can be detected
unambiguously when the sample contains at least 1 % mass asphaltenes as measured by Test Method D6560.
NOTE 2—This test method is applicable to products typical of Specification D396—Grades 5L, 5H, and 6, and Specification D2880—Grades 3-GT and
4-GT.
1.3 This test method was evaluated in an interlaboratory study in the nominal range of 32 to 76 for the maximum flocculation
ratio and in the nominal range of 36 to 95 for peptizing power.
NOTE 3—The nominal range is determined by (min. sample mean—Reproducibility) to (max. sample mean + Reproducibility).
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D396 Specification for Fuel Oils
D2880 Specification for Gas Turbine Fuel Oils
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D4870 Test Method for Determination of Total Sediment in Residual Fuels
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
D6560 Test Method for Determination of Asphaltenes (Heptane Insolubles) in Crude Petroleum and Petroleum Products
D6792 Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
3. Terminology
3.1 Definitions:
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.14 on Stability, Cleanliness and Compatibility of Liquid Fuels.
Current edition approved Dec. 1, 2019May 1, 2020. Published December 2019June 2020. Originally approved in 2004. Last previous edition approved in 20142019 as
D7060 – 12 (2014).(2019). DOI: 10.1520/D7060-12R19.10.1520/D7060-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
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3.1.1 asphaltenes, n—(rarely used in the singular), in petroleum technology, represent an oil fraction that is soluble in a specified
aromatic solvent but separates upon addition of an excess of a specified paraffinic solvent.
3.1.1.1 Discussion—
In this test method, the aromatic solvent is 1-methylnapthalene, and the paraffinic solvent is n-hexadecane.
3.1.2 compatibility, n— of crude oils or of heavy fuel oils, the ability of two or more crude oils or fuel oils to blend together
within certain concentration ranges without evidence of separation, such as the formation of multiple phases.
3.1.2.1 Discussion—
Incompatible heavy fuel oils or crude oils, when mixed or blended, result in the flocculation or precipitation of asphaltenes. Some
oils may be compatible within certain concentration ranges in specific mixtures, but incompatible outside those ranges.
3.1.3 flocculation, n— of asphaltenes from crude oils or heavy fuel oils, the aggregation of colloidally dispersed asphaltenes into
visibly larger masses which may or may not settle.
3.1.4 peptization, n— of asphaltenes in crude oils or heavy fuel oils, the dispersion of asphaltenes to produce a colloidal
dispersion.
3.1.5 stability reserve, n— in petroleum technology,of crude oils, heavy fuel oils, and residual streams containing asphaltenes,
the property of an oil to maintain asphaltenes in a peptized (colloidally dispersed) state and prevent flocculation of the asphaltenes.
3.1.5.1 Discussion—
An oil with a low stability reserve is likely to undergo flocculation of asphaltenes when stressed (for example, extended heated
storage) or blended with a range of other oils. Two oils each with a high stability reserve are likely to maintain asphaltenes in a
peptized state and not lead to flocculation when blended together.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 critical cetane dilution, n—number of millilitres of cetane with which 1 g of undiluted sample can be diluted until it just
does not flocculate the asphaltenes.
3.2.2 critical dilution, n—number of millilitres of 1-methylnaphthalene and cetane with which 1 g of undiluted sample can be
diluted until it just does not flocculate the asphaltenes.
3.2.2.1 Discussion—
The number of millilitres of 1-methylnaphthalene and cetane is variable and depends on the ratio of sample to 1-methylnaphthalene
at the starting point and the sample type.
3.2.3 flocculation ratio, n—percentage by volume of 1-methylnaphtalene in a mixture of 1-methylnaphthalene and cetane.
3.2.4 flocculation ratio at critical dilution, n—percentage by volume of 1-methylnaphthalene in a mixture of
1-methylnaphthalene and cetane at the inflection point.
3.2.5 inflection point, n—last step during the titration with cetane, where flocculation of asphaltenes is not detected by the
optical probe as a significant and sustained increase in rate-of-change of signal.
3.2.6 maximum flocculation ratio, n—of asphaltenes, minimum required solvency power, expressed as percentage by volume
of 1-methylnaphthalene in a mixture of 1-methylnaphthalene and cetane, to keep the asphaltenes in a colloidal solution.
3.2.6.1 Discussion—
Maximum flocculation ratio is the flocculation ratio at extrapolated infinite dilution of the sample.
3.2.7 oil medium, n—that portion of a sample of heavy fuel oil or crude oil that surrounds and colloidally disperses the
asphaltenes.
3.2.7.1 Discussion—
For purposes of this test method, an oil sample is considered to be composed of an oil medium (sometimes called an oil matrix
or maltenes) and asphaltenes.
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3.2.8 peptizing power, n—available solvency power, expressed as percentage by volume of 1-methylnaphthalene in a mixture
of 1-methylnaphthalene and cetane, to keep asphaltenes in a colloidal solution.
3.2.9 reciprocal dilution, n—dilution ratio of sample in solvent mixture of 1-methylnaphthalene and cetane.
3.3 Symbols:
FR = maximum flocculation ratio
max
FR = flocculation ratio at critical dilution
x
Po = peptizing power
Xmin = critical cetane dilution
Xc = critical dilution
4. Summary of Test Method
4.1 Six portions of the sample are diluted in various ratios with 1-methylnaphthalene. Each solution is inserted into the
automatic apparatus, and titrated with cetane until flocculation of asphaltenes is detected by the optical probe. The first two
solutions are titrated with cetane in coarse determinations in which the flocculation ratio is decreased in 5 % steps. The coarse
determinations help to establish suitable starting values for the fine determinations, in which the flocculation ratio is decreased in
1 % steps. The four flocculation ratios at critical dilution, measured during the fine determinations, are used to calculate the
maximum flocculation ratio of the sample’s asphaltenes and the peptizing power of the sample’s oil medium.
5. Significance and Use
5.1 Asphaltenes are naturally occurring materials in crude petroleum and petroleum products containing residual material. The
asphaltenes are usually present in colloidal suspensions, but they may agglomerate and flocculate if the suspension of asphaltene
molecules is disturbed through excess stress or incompatibility. This test method provides compatibility parameters, which can be
used to assess stability reserve and compatibility.
3,4
5.2 A blend is considered stable when the blend’s peptizing power is higher than the blend’s maximum flocculation ratio; both
of them can be calculated using empirical blend rules. Refineries and terminal owners can prevent the flocculation of asphaltenes
due to incompatibility by assessing the compatibility of fuels beforehand.
NOTE 4—See Appendix X1 for an example of prediction of compatibility.
6. Interferences
6.1 High content of insoluble inorganic matter (sediment) has some interference in this test method. In this case, the insoluble
matter shall be removed by filtration according to Test Method D4870.
6.2 The presence of wax, present in paraffinic crudes or fuels from such crudes, does not interfere.
7. Apparatus
7.1 Integrated Automated Analytical Measurement System—This test method uses an integrated automated analytical
measurement system comprised of a PC–based computer and two titration stations (Fig. 1). See Annex A1 for detailed
information.
7.2 The computer controls test sequencing, acquires and accumulates optical probe signal data, provides processing
calculations, and automatically produces a report of important test parameters. The computer is capable of controlling one or two
independent titration stations.
7.3 Each titration station consists of the following:
7.3.1 Automatic titration unit,
7.3.2 Heater,
7.3.3 Magnetic stirrer,
7.3.4 Optical probe, and
7.3.5 Reaction cell plus lid.
7.4 Magnetic Stirrer/Hotplate, thermostatically controlled.
7.5 Stirring Bar, magnetic, PFTE-coated, 25 mm in length.
Berryman, T. J., and Lewis, C. P. G., “The Stability of Residual Fuels. Theory and Practice of the Shell Concept,” 16th CIMAC Conference, Oslo, 1985.
Berg van den, F. G. A., “Developments in Fuel Oil Blending,” IASH 7th International Conference, Graz, Austria, 2000.
The sole source of supply of the apparatus known to the committee at this time is Automated Stability Analyser, (User Manual, Version 2), available from Zematra, 3194
DG Hoogvliet, The Netherlands. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive
careful consideration at a meeting of the responsible technical committee, which you may attend.
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FIG. 1 Titration Stations of Integrated Automated Analytical Measurement System
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such
specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity
to permit its use without lessening the accuracy of the determination.
8.2 Asphaltene Solution (3 g/L)—Dissolve 0.15 g of dry asphaltenes in 1-methylnaphthalene and dilute to 50 mL. A procedure
to obtain asphaltenes is described in Appendix X2. Prepare fresh daily, as needed.
8.3 Cetane (n-Hexadecane). (Warning—Irritating to respiratory system and skin.)
8.4 Cleaning Solvent, technical grade, 95 % purity, for cleaning. It consists of one of the following:
8.4.1 Tetrahydrofuran, stabilized. (Warning—Extremely flammable. Irritating to eyes and respiratory system.)
8.4.2 Toluene. (Warning—Flammable. Health Hazard.)
8.4.3 Xylene. (Warning—Flammable. Harmful by inhalation and in contact with skin. Irritating to skin.)
8.5 n-Heptane. (Warning—Flammable. Vapor harmful. Vapor may cause flash fire.)
8.6 1-Methylnaphthalene. (Warning—Harmful if swallowed. Irritating to skin.)
8.7 Quality Control (QC) Sample, a stable and homogeneous residual fuel oil. The QC sample contains at least 1 % by mass
2 2
asphaltenes and has approximate viscosities in the range of 180 mm to 380 mm /s at 50 °C.
9. Sampling and Test Specimens
9.1 Sampling:
9.1.1 Obtain samples in accordance with Practices D4057 or D4177.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference Materials, American Chemical Society, Washington, DC. For
suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and
the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D7060 − 20
9.1.2 Samples of very viscous materials may be warmed until they are reasonably fluid before they are sampled.
9.1.3 Store samples prior to taking test specimens at ambient temperatures.
9.2 Test Specimen Preparation:
9.2.1 Sample Fuel Temperature—Warm viscous samples until they can be mixed readily before opening the storage container.
For fuels with a high wax content (high pour point) the temperature shall be at least 15 °C above the pour point.
9.2.2 Shake or mix the sample thoroughly. If the sample contains a high content of insoluble matter, filter the sample through
a 47 mm diameter glass fiber filter medium (such as Whatman Grade GF/A) using the Test Method D4870 filtration apparatus.
9.2.3 Preparation of Six Specimen Blends—Visually check the reaction cell and the lid for cleanliness. Dissolve specimen in
1-methylnaphthalene in several different ratios of solvent according to Table 1. Prepare the blends shortly before the test procedure.
Generally follow the sequence: (1) prepare and test Blends A1 and C1, (2) prepare and test Blends A2 and C2, and (3) prepare
and test Blends B and D.
NOTE 5—Blends A1 and B1 can be omitted when the coarse determinations are skipped. See also 12.1.1.1.
9.2.3.1 Weigh, according to Table 1, specimen to the nearest 0.01 g into a clean reaction cell and add a PFTE-coated magnetic
stirring bar. Place the reaction cell in the center of the preheated (approximately 150 °C) magnetic stirrer/hotplate and switch on
the magnetic stirrer. Allow the specimen to warm up, until its viscosity is low enough to obtain a smooth stirring performance.
9.2.3.2 Add, according to Table 1, while continuously stirring, an appropriate volume of 1-methylnaphthalene to the nearest
0.01 mL.
9.2.3.3 Put the lid in place. Initiate the test procedure (12.3) within 10 min.
NOTE 6—Never use excessive force when placing the lid in place.
10. Preparation of Apparatus
10.1 Prepare the instrument for operation in accordance with the manufacturer’s instructions.
10.2 Inspect the optical probe’s glass surface for cleanliness and damage before use. Connect the optical probes to the respective
apparatus’ titration station. Place the optical probes in the holder at the back of the corresponding titration station.
10.3 Cleaning Instructions—Perform the following cleaning procedure after the test procedure (see 12.3).
10.3.1 Remove the dosing tube. Clean the tube with a clean, lintless cloth. Place the tube into its storage place.
10.3.2 Carefully remove the optical sensor from the reaction cell. (Warning—The hot sensor and reaction cell can cause severe
burns.) Clean the optical sensor with a clean, lintless soft cloth using an appropriate solvent (see 8.4). Place the sensor in the holder
on top of the reaction cell heater.
10.3.3 Take the reaction cell from the heater using wooden cla
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