ASTM D7112-19

Standard Test Method for Determining Stability and Compatibility of Heavy Fuel Oils and Crude Oils by Heavy Fuel Oil Stability Analyzer (Optical Detection)

SIGNIFICANCE AND USE
5.1 Automatic determination of stability parameters using a light back-scattering technique improves accuracy and removes human errors. In manual testing, operators have to visually compare oil stains on pieces of filter paper to determine if asphaltenes have been precipitated.  
5.2 Refinery thermal and hydrocracking processes can be run closer to their severity limits if stability parameters can be calculated more accurately. This gives increased yield and profitability.  
5.3 Results from the test method could be used to set a standard specification for stability parameters for fuel oils.  
5.4 The compatibility parameters of crude oils can be used in crude oil blending in refineries to determine, in advance, which crude oil blends will be compatible and thus can be used to minimize plugging problems, unit shut downs, and maintenance costs. Determination of crude oil compatibility parameters also enables refineries to select crude oil mixtures more economically.  
5.5 This test method can measure stability and compatibility parameters, and determine stability reserve on different blends for particular applications to optimize the blending, storage, and use of heavy fuel oils
Note 1: Users of this test method would normally use stability and compatibility parameters to determine stability reserve of residual products, fuel blends and crude oils. However, the interpretation of stability, stability reserve and compatibility is heavily ‘use dependent,’ and is beyond the scope of this test method.
SCOPE
1.1 This test method covers an automated procedure involving titration and optical detection of precipitated asphaltenes for determining the stability and compatibility parameters of refinery residual streams, residual fuel oils, and crude oils. Stability in this context is the ability to maintain asphaltenes in a peptized or dissolved state and not undergo flocculation or precipitation. Similarly, compatibility relates to the property of mixing two or more oils without precipitation or flocculation of asphaltenes.  
1.2 This test method is applicable to residual products from atmospheric and vacuum distillation, from thermal, catalytic, and hydrocracking processes, to products typical of Specifications D396, Grades No. 5L, 5H, and 6, and D2880, Grades No. 3-GT and 4-GT, and to crude oils, providing these products contain 0.05 mass % or greater concentration of asphaltenes.  
1.3 This test method is not relevant to oils that contain less than 0.05 % asphaltenes, and would be pointless to apply to unstable oils that already contain flocculated asphaltenes.  
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: 31-May-2019
• 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 D7112-18 - Standard Test Method for Determining Stability and Compatibility of Heavy Fuel Oils and Crude Oils by Heavy Fuel Oil Stability Analyzer (Optical Detection)
• Effective Date: 01-Jun-2019
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D396-19a - Standard Specification for Fuel Oils
• Effective Date: 15-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 D6299-17b - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Dec-2017
• Refers: ASTM D396-17a - Standard Specification for Fuel Oils
• Effective Date: 01-Dec-2017
• Refers: ASTM D6299-17a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Nov-2017
• Refers: ASTM D396-17 - Standard Specification for Fuel Oils
• Effective Date: 01-Jul-2017
• Refers: ASTM D6299-17 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jan-2017

Overview

ASTM D7112-19 is the internationally recognized standard test method for determining the stability and compatibility of heavy fuel oils and crude oils using a heavy fuel oil stability analyzer with optical detection. Developed by ASTM International, this standard offers an automated, highly accurate method to assess the tendency of asphaltenes in petroleum products to remain dissolved or peptized-crucial factors in refining operations and fuel blending. The method automates the titration and detection of asphaltene precipitation, minimizing human error and improving reproducibility over traditional manual testing.

Key Topics

• Stability Analysis: The method evaluates a fuel's ability to maintain asphaltene stability, preventing unwanted precipitation and associated operational issues.
• Compatibility Assessment: Tests determine if different crude oils or fuel oils can be safely blended without causing asphaltene flocculation.
• Automated Optical Detection: By applying a titration process and measuring light back-scattering, the analyzer provides objective, precise results.
• Parameters Measured:
  • P-value: Indicates solvency power against asphaltene precipitation.
  • Flocculation Ratio (FR): Reveals at which solvent compositions asphaltenes begin to precipitate.
  • Solvent Equivalent (SE): The minimum aromatic solvent content to prevent flocculation.
  • Insolubility Number (Iₙ) and Solubility Blending Number (SBN): Key factors for predicting blend compatibility in crude oil mixtures.
• Improved Refinery Processes: Accurate data support the operation of thermal and hydrocracking processes closer to their severity limits, enhancing yield and profitability.
• Quality Control in Fuel Blending: The results can inform specifications for stability parameters, aiding consistent product quality across batches.

Applications

• Refinery Operations: Refineries use this test method to optimize thermal, catalytic, and hydrocracking processes by closely monitoring asphaltene stability, which limits fouling and shutdowns.
• Crude Oil Blending: The compatibility parameters enable refineries to predict the behavior of crude oil mixtures, reducing the risk of plugging and unplanned maintenance.
• Residual Fuel Quality Assessment: The method applies to residual products from atmospheric/vacuum distillation and various cracked residues, essential for monitoring heavy marine fuel and industrial fuel oil quality.
• Product Specification and Compliance: Supports standardization in procurement and sales of heavy fuel oils and crude blends by providing reliable data on stability and compatibility.
• Operational Cost Reduction: By preventing compatibility issues, operators can select crude mixes more economically, minimize processing interruptions, and extend equipment life.
• Automated Laboratory Testing: The use of automated analyzers reduces operator variability, improves safety (less exposure to hazardous solvents), and ensures data reliability for quality assurance programs.

Related Standards

• ASTM D396 - Specification for Fuel Oils
  Governs the requirements for commercial fuel oils, to which D7112 data may apply for quality assurance.
• ASTM D2880 - Specification for Gas Turbine Fuel Oils
  Relevance to products intended for gas turbines, where asphaltene content and stability are critical.
• ASTM D4057 & D4177 - Practices for Manual and Automatic Sampling
  Ensure representative sampling, an essential prerequisite for accurate stability testing.
• ASTM D6560 - Test Method for Asphaltene Content
  Offers supporting data on asphaltene levels, a foundational metric for applying the D7112 test.
• ASTM D4175 - Terminology
  Standard definitions for terms applied throughout D7112 and related petroleum product testing.
• ASTM D6299 - Statistical Quality Control
  Guidance for implementing control charts and monitoring analytical system performance in labs using D7112.

This test method enables refineries, fuel suppliers, and laboratories to optimize processes and fuel quality by providing reliable, accurate measurements of stability and compatibility. The automation and optical detection significantly reduce manual errors, offering dependable results essential for the modern petroleum industry.

Keywords: ASTM D7112-19, heavy fuel oil stability, crude oil compatibility, asphaltene precipitation, optical detection, refinery blending, automated fuel testing, petroleum product standards.

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: D7112 − 19
Standard Test Method for
Determining Stability and Compatibility of Heavy Fuel Oils
and Crude Oils by Heavy Fuel Oil Stability Analyzer (Optical
Detection)
This standard is issued under the fixed designation D7112; 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* 2. Referenced Documents
1.1 This test method covers an automated procedure involv- 2.1 ASTM Standards:
ing titration and optical detection of precipitated asphaltenes D396 Specification for Fuel Oils
for determining the stability and compatibility parameters of D2880 Specification for Gas Turbine Fuel Oils
refinery residual streams, residual fuel oils, and crude oils. D4057 Practice for Manual Sampling of Petroleum and
Stability in this context is the ability to maintain asphaltenes in Petroleum Products
a peptized or dissolved state and not undergo flocculation or D4175 Terminology Relating to Petroleum Products, Liquid
precipitation. Similarly, compatibility relates to the property of Fuels, and Lubricants
mixingtwoormoreoilswithoutprecipitationorflocculationof D4177 Practice for Automatic Sampling of Petroleum and
asphaltenes. Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance
1.2 This test method is applicable to residual products from
and Control Charting Techniques to Evaluate Analytical
atmospheric and vacuum distillation, from thermal, catalytic,
Measurement System Performance
and hydrocracking processes, to products typical of Specifica-
D6560 Test Method for Determination ofAsphaltenes (Hep-
tions D396, Grades No. 5L, 5H, and 6, and D2880, Grades No.
tane Insolubles) in Crude Petroleum and Petroleum Prod-
3-GT and 4-GT, and to crude oils, providing these products
ucts
contain 0.05 mass % or greater concentration of asphaltenes.
1.3 This test method is not relevant to oils that contain less
3. Terminology
than 0.05 % asphaltenes, and would be pointless to apply to
3.1 Definitions:
unstable oils that already contain flocculated asphaltenes.
3.1.1 For definitions of some terms used in this test method,
1.4 The values stated in SI units are to be regarded as
such as crude oil, repeatability, reproducibility, and residual
standard. No other units of measurement are included in this
fuel oil, refer to Terminology D4175.
standard.
3.1.2 asphaltenes, n—(rarely used in the singular), in petro-
leum technology, represent an oil fraction that is soluble in a
1.5 This standard does not purport to address all of the
specified aromatic solvent but separates upon addition of an
safety concerns, if any, associated with its use. It is the
excess of a specified paraffinic solvent.
responsibility of the user of this standard to establish appro-
3.1.2.1 Discussion—In this test method, the aromatic sol-
priate safety, health, and environmental practices and deter-
vent is xylene and the paraffinic solvent is n-heptane.
mine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accor-
3.1.3 compatibility, n—of crude oils or of heavy fuel oils,
dance with internationally recognized principles on standard-
the ability of two or more crude oils or fuel oils to blend
ization established in the Decision on Principles for the
together within certain concentration ranges without evidence
Development of International Standards, Guides and Recom-
of separation, such as the formation of multiple phases.
mendations issued by the World Trade Organization Technical
3.1.3.1 Discussion—Incompatible heavy fuel oils or crude
Barriers to Trade (TBT) Committee.
oils, when mixed or blended, result in the flocculation or
precipitation of asphaltenes. Some oils may be compatible
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 June 1, 2019. Published June 2019. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2005. Last previous edition approved in 2018 as D7112 – 18. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7112-19. 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
D7112 − 19
within certain concentration ranges in specific mixtures, but extrapolated to infinite dilution of the sample at the y-axis
incompatible outside those ranges. (where (1/X)=0.See Eq 3).
3.1.4 flocculation, n—of asphaltenes from crude oils or
3.2.7 oil matrix, n—that portion of a sample of heavy fuel
heavy fuel oils, the aggregation of colloidally dispersed as-
oil or crude oil that surrounds and colloidally disperses the
phaltenes into visibly larger masses which may or may not
asphaltenes.
settle.
3.2.7.1 Discussion—For purposes of this test method, an oil
sample is considered to be composed of an oil matrix (some-
3.1.5 stability reserve, n—of crude oils, heavy fuel oils, and
times called an oil medium) and asphaltenes.
residual streams containing asphaltenes, the property of an oil
to maintain asphaltenes in a peptized (colloidally dispersed) 3.2.8 P-value, n—of refinery residual steams, residual fuel
state and prevent flocculation of the asphaltenes.
oils and crude oils, an indication of the stability or available
solvency power of an oil with respect to precipitation of
3.1.5.1 Discussion—An oil with a low stability reserve is
asphaltenes.
likelytoundergoflocculationofasphalteneswhenstressed(for
example, extended heated storage) or blended with a range of 3.2.8.1 Discussion—Since the equation defining P-value is
P=(1+ X ),where X istheminimumvolumeofparaffinic
other oils.Two oils each with a high stability reserve are likely
min min
solvent, n-heptane, (in mL) needed to be added to1gofoilto
to maintain alsphaltenes in a peptized state and not lead to
result in flocculation of asphaltenes, the smallest P-value is 1,
flocculation when blended together.
which means the oil is unstable and can precipitate asphaltenes
3.2 Definitions of Terms Specific to This Standard:
without addition of any paraffinic solvent. A higher P-value
3.2.1 aromatic solvent equivalent (xylene equivalent), SE,
indicates that an oil is more stable with respect to flocculation
n—the lowest aromatic solvent (xylene) content, expressed as
of asphaltenes. P-value by this test method relates specifically
a volume %, in a mixture containing aromatic and paraffinic
toxyleneand n-heptaneasthearomaticandparaffinicsolvents,
solvents (xylene and n-heptane) which, when mixed with oil,
respectively.
will not result in flocculation of asphaltenes. See flocculation
3.2.9 P,n—the P-value of an asphaltene, which is the
a
ratio.
peptizability or ability of an asphaltene to remain colloidally
3.2.1.1 Discussion—SE is defined as FR multiplied by
5/1
dispersed.
100 %, as shown in Eq 2.
3.2.10 P,n—the P-value of an oil matrix. See oil matrix.
o
3.2.2 evaporation correction coeffıcient, n—the rate of
3.2.11 peptize, v—of an oil or cutter stock, to dissolve an
evaporation of aromatic solvent (xylene) from the sample cup,
asphaltene or to maintain an asphaltene in colloidal dispersion.
measured in grams per hour.
3.2.12 solubility blending number, S ,n—a crude oil
BN
3.2.3 flocculationratio(FR),n—thelowestaromaticsolvent
blending model parameter which can be used to determine if
(xylene) concentration, expressed as a proportion of xylene to
blends of oils are incompatible or compatible. See insolubility
xylene plus n-heptane which, when mixed with an oil, will not
number.
result in flocculation of asphaltenes. See 15.1, Eq 1.
3.2.12.1 Discussion—Solubility blending numbers for indi-
3.2.4 FR ,n—theflocculationratioatadilutionof5mLof
5/1
vidual oils are determined and calculated from the density of
xylene and n-heptane solvent mixture to1gof oil.
the oil, aromatic solvent equivalent value, and volume of
3.2.4.1 Discussion—The ratio 5 to 1 is used internally by a
paraffinic solvent that can be added to 5 mL of oil without
number of oil companies involved with the stability and
asphaltene precipitation. The equations are given under Calcu-
compatibility of heavy fuel oils and crude oils. This ratio is
lation of Results (see 15.2).
chosen so that a P-value of six represents an FR of zero.
5/1
3.2.13 step size, n—the volume in mL of each portion of
3.2.5 insolubility number, I ,n—a crude oil blending model
n-heptane added to the stock solution in the course of the test
N
parameter which can be used to determine if blends of oils are procedure.
compatible or incompatible. See solubility blending number.
3.2.14 stock solution, n—a solution of a sample dissolved in
3.2.5.1 Discussion—Insolubility numbers for individual oils
a specific amount of xylene.
are determined and calculated from the density of the oil,
3.3 Symbols:
aromatic solvent equivalent value and volume of paraffinic
FR = flocculation ratio
solvent (n-heptane) that can be added to 5 mL of oil without
FR = flocculation ratio at a dilution of 5 mL solution
5/1
asphaltene precipitation. The equations are given under Calcu-
(xylene plus n-heptane) to1gofoil
lation of Results (see 15.2).
FR = maximum flocculation ratio
max
3.2.6 maximumflocculationratio,FR ,n—ofasphaltenes
max I = insolubility number
N
in residual fuel oils and crude oils, the minimum required
P = the P-value of an oil
solvency power of a solvent mixture, expressed as a ratio by
P = the P-value of an asphaltene
a
volume of aromatic solvent (xylene) to aromatic solvent plus
P = the P-value or peptizing power of an oil matrix
o
paraffinic solvent (n-heptane) to keep the asphaltenes in an oil
S = solubility blending number
BN
colloidally dispersed.
SE = xylene equivalent, volume %
3.2.6.1 Discussion—FR is determined from a plot of X = n-heptane consumption of undiluted oil, in mL/g of
max min
flocculation ratios versus the oil concentration in solvent, oil
D7112 − 19
4. Summary of Test Method 7. Apparatus
7.1 PORLA Heavy and Crude Oil Stability and Compatibil-
4.1 Stability and compatibility parameters are determined
3,4
ity Analyzer —See Figs. 1 and 2.
by titration and optical detection of precipitated asphaltenes.A
7.1.1 Aportion of the apparatus is shown diagrammatically
stock solution is prepared and three different mixtures of the
in Fig. 2 and is comprised of the following parts:
sample oil plus xylene are titrated with n-heptane to cause
7.1.1.1 Sample Cup, light weight, inert cups designed to fit
precipitation of asphaltenes. The titrated mixture is continu-
ously circulated through an optical detector which detects the sample carousel, with a smooth, flat bottom, volume
approximately 100 mL. Typically, aluminum cups have been
precipitatedasphaltenesbyback-scatteringofvisiblelight.The
used.
amounts of oil, xylene, and n-heptane are used to calculate
7.1.1.2 Sample Carousel, typically a four-position sample
stability parameters: solvent equivalent, P-value, and FR .If
5/1
cup holder delivering the sample cups sequentially to the
the density of a crude oil sample is known, then the compat-
measurement position.
ibility parameters (S and I ) of the crude oil may also be
BN N
calculated. 7.1.1.3 Mixer Lift System, vertically moving lift system,
forming a seal with the sample cup in the measurement
position and incorporating a mechanical stirrer which starts to
5. Significance and Use
rotate when the seal is made. It also incorporates delivery lines
5.1 Automatic determination of stability parameters using a
for n-heptane and xylene addition, the circulation line for
light back-scattering technique improves accuracy and re-
passing the sample through the detector and the exhaust line,
moves human errors. In manual testing, operators have to
which empties the sample cup after analysis.
visually compare oil stains on pieces of filter paper to deter-
7.1.1.4 Aromatic Solvent Pump, accurate and adjustable
mine if asphaltenes have been precipitated.
ceramic piston pump, capable of delivering xylene at a rate of
0.01 mL⁄s to 0.5 mL/s.
5.2 Refinery thermal and hydrocracking processes can be
run closer to their severity limits if stability parameters can be 7.1.1.5 Paraffınic Solvent Pump, accurate and adjustable
ceramic piston pump, capable of delivering n-heptane at a rate
calculated more accurately. This gives increased yield and
of 0.01 mL⁄s to 0.5 mL/s.
profitability.
7.1.1.6 Circulation Pump, accurate and adjustable ceramic
5.3 Results from the test method could be used to set a
pistonpumpusedtocirculatethesampleundertestthroughthe
standard specification for stability parameters for fuel oils.
detector system.
5.4 The compatibility parameters of crude oils can be used 7.1.1.7 Exhaust Pump, accurate and adjustable ceramic
piston pump used to empty the sample cup at the end of the
in crude oil blending in refineries to determine, in advance,
measurement.
which crude oil blends will be compatible and thus can be used
to minimize plugging problems, unit shut downs, and mainte-
7.1.1.8 Detector System, (see Fig. 3) optical detector
nance costs. Determination of crude oil compatibility param- through which the sample solution is continuously circulated.
eters also enables refineries to select crude oil mixtures more The detector is composed of a visible light source and a
photodiode for recording the light reflecting from asphaltene
economically.
particles in the test sample.
5.5 Thistestmethodcanmeasurestabilityandcompatibility
7.1.1.9 Hot Plate, a temperature controlled heating system
parameters, and determine stability reserve on different blends
maybelocatedbelowthesamplecups,whichwillwarmupthe
for particular applications to optimize the blending, storage,
sample so that the titration may be performed at an elevated
and use of heavy fuel oils
temperature. The temperature of the hot plate should be
adjustable between 20 °C and 100 °C.
NOTE 1—Users of this test method would normally use stability and
compatibility parameters to determine stability reserve of residual
products, fuel blends and crude oils. However, the interpretation of
stability,stabilityreserveandcompatibilityisheavily‘usedependent,’and
The PORLA Heavy and Crude Oil Stability and Compatibility Analyzer is
is beyond the scope of this test method.
covered by Euro patent EP 0737309 and U.S. patent US5715046. Interested parties
are invited to submit information regarding the identification of an alternative(s) to
6. Interferences
this patented item to the ASTM International Headquarters. Your comments will
receive careful consideration at a meeting of the responsible technical committee,
6.1 Free water present in the oil can cause difficulties with
which you may attend.
The sole source of supply of the PORLA Heavy and Crude Oil Stability and
the optical detector and should be removed by centrifuging
CompatibilityAnalyzerknowntothecommitteeatthistimeisFinnishMeasurement
prior to testing.
Systems Limited, Koskikuja 5, FIN-71570 Syvanniemi, Finland,
www.finnmeassys.com. If you are aware of alternative suppliers, please provide this
6.2 Solid particles, such as coke or wax particles, mud,
information to ASTM International Headquarters. Your comments will receive
sand, or catalyst fines, in the oil will not affect the optical 1
careful consideration at a meeting of the responsible technical committee, which
detector or interfere with the results. you may attend.
D7112 − 19
FIG. 1 PORLA Heavy and Crude Oil Stability and Compatibility Analyzer
7.1.2 Computer, controls the measurement and calibration specifications are available. Other grades may be used, pro-
programs and is an interface between the operator and the vided it is first determined that the reagents are of sufficiently
analyzer. high purity to permit their use without lessening the accuracy
of the determination.
7.1.3 PORLA Step Measurement Screen, computer display,
allowing data about the sample and operator to be input as well
8.2 Xylene (C H )—The xylene used is generally a mixture
8 10
as showing the results of each titration (see Fig. 4).
of ortho, meta, and para isomers and may contain some ethyl
7.1.4 Parameter Screen, computer display, allows all of the benzene. (Warning—Flammable, health hazard.)
measurement cycle parameters to be adjusted from the default
8.3 n-heptane (C H )—(Warning—Flammable, health
7 16
values and also allows the pump calibration procedure to be
hazard.)
run (see Fig. 5).
8. Reagents and Materials
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
8.1 Purity of Reagents—Reagent grade chemicals shall be
listed by the American Chemical Society, see Analar Standards for Laboratory
used in all tests. Unless otherwise indicated, all reagents shall
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
conform to the specifications of the Committee on Analytical
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Reagents of the American Chemical Society where such MD.
D7112 − 19
FIG. 2 Schematic Diagram of PORLA Heavy and Crude Oil Stability and Compatibility Analyzer
10. Sampling and Test Specimens
10.1 Obtain samples in accordance with procedures de-
scribed in Practices D4057 or D4177. Ensure that samples are
representative of the whole batch of oil.
10.2 Aminimum sample size of 40 g is required for a single
test. It is preferable to collect a larger sample such as 200 g to
500 g to allow for multiple testing, if necessary.
10.3 Ensure that the sample is homogeneous before with-
drawing an aliquot or test specimen for testing.
10.4 To avoid changes or degradation of oil samples,
minimize exposure to air, temperatures above 25 °C, and light.
Store samples in sealed, opaque containers such as metal cans
or dark glass bottles.
11. Preparation of Apparatus
11.1 Review the operations manual for the apparatus, and
follow all recommended steps. The following actions summa-
rize the preparation of the apparatus:
FIG. 3 Schematic Diagram of PORLA Heavy and Crude Oil Stabil-
11.1.1 Place the apparatus on a level surface, in a well-
ity and Compatibility Analyzer Detector
ventilated area such as a fume hood.
11.1.2 Connect the analyzer and the computer to a suitable
9. Hazards ac power source, and connect the analyzer, keyboard, monitor,
and mouse to the computer with the cables supplied.
9.1 Place the analyzer in a fume hood or similar well
ventilated area to minimize exposure of operators to harmful
NOTE 2—All of the controls for the instrument except for the main
vapors. power switch are accessed by means of the keyboard and mouse of the
computer.
9.2 Operators should use proper protective laboratory cloth-
11.1.3 Fill the aromatic and paraffinic solvent bottles with
ing and gloves to avoid skin exposure to oil samples and
xylene and n-heptane, respectively, and ensure the waste bottle
solvents. In addition, operators should be careful when han-
dling hot oil containers when preparing the stock solutions
from very viscous oils as oil spills on exposed skin will cause
burns. Obtain the operator’s manual from the supplier of the apparatus.
D7112 − 19
FIG. 4 PORLA Step Measurement Screen
is empty. Connect the three plastic bottles, labeled aromatic 12.1.4 Weigh the collected solvent and sample cup and
solvent, paraffinic solvent and waste, to the appropriate lines subtract the tare weight of the sample cup to give the weight of
from the analyzer.
solvent pumped in the set time period (60 s).
11.1.4 Switchtheanalyzeronusingtherockerswitchonthe
12.1.5 Enter the weight of solvent collected in the appro-
back panel.Agreen lamp will illuminate on the upper right of
priate screen.
the front panel.
12.1.5.1 For the xylene pump rate, the instrument calculates
11.1.5 Switch on the computer and allow it to boot up.
the updated pump rate in g/s and displays it in the appropriate
11.1.6 Select either PORLAStep or PORLATest by double
field in the parameter screen.
clicking the mouse on the appropriate icon to bring up the
12.1.5.2 For the n-heptane pump rate, the instrument calcu-
PORLA Step measurement screen (see Fig. 4) or the system
lates the updated pump rate and displays it in mL/s in the
test screen.
appropriate field in the parameter screen.
12. Calibration and Standardization
12.2 Evaporation Correction Coeffıcient—Determine the
12.1 Pump Calibration—Perform the pump calibration at
evaporation correction coefficient for the xylene by weighing
the initial set-up and whenever the instrument has been
(accurate to two decima
...

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: D7112 − 18 D7112 − 19
Standard Test Method for
Determining Stability and Compatibility of Heavy Fuel Oils
and Crude Oils by Heavy Fuel Oil Stability Analyzer (Optical
Detection)
This standard is issued under the fixed designation D7112; 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*
1.1 This test method covers an automated procedure involving titration and optical detection of precipitated asphaltenes for
determining the stability and compatibility parameters of refinery residual streams, residual fuel oils, and crude oils. Stability in
this context is the ability to maintain asphaltenes in a peptized or dissolved state and not undergo flocculation or precipitation.
Similarly, compatibility relates to the property of mixing two or more oils without precipitation or flocculation of asphaltenes.
1.2 This test method is applicable to residual products from atmospheric and vacuum distillation, from thermal, catalytic, and
hydrocracking processes, to products typical of Specifications D396, Grades No. 5L, 5H, and 6, and D2880, Grades No. 3-GT and
4-GT, and to crude oils, providing these products contain 0.05 mass % or greater concentration of asphaltenes.
1.3 This test method is not relevant to oils that contain less than 0.05 % asphaltenes, and would be pointless to apply to unstable
oils that already contain flocculated asphaltenes.
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
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6560 Test Method for Determination of Asphaltenes (Heptane Insolubles) in Crude Petroleum and Petroleum Products
3. Terminology
3.1 Definitions:
3.1.1 For definitions of some terms used in this test method, such as crude oil, repeatability, reproducibility, and residual fuel
oil, refer to Terminology D4175.
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 July 1, 2018June 1, 2019. Published July 2018June 2019. Originally approved in 2005. Last previous edition approved in 20172018 as
D7112 – 12 (2017).D7112 – 18. DOI: 10.1520/D7112-18.10.1520/D7112-19.
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
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7112 − 19
3.1.2 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.
3.1.2.1 Discussion—
In this test method, the aromatic solvent is xylene and the paraffinic solvent is n-heptane.
3.1.3 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.
3.1.3.1 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.
3.1.4 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.
3.1.5 stability reserve, n—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 their flocculation when stored or when blended with
other oils.flocculation of the asphaltenes.
3.1.5.1 Discussion—
An oil with a high stability reserve can be stored for a long period of time 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 without flocculation of
asphaltenes.oils. Two oils each with a high stability reserve are likely to maintain alsphaltenes in a peptized state and not lead to
flocculation when blended together.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 aromatic solvent equivalent (xylene equivalent), SE, n—the lowest aromatic solvent (xylene) content, expressed as a
volume %, in a mixture containing aromatic and paraffinic solvents (xylene and n-heptane) which, when mixed with oil, will not
result in flocculation of asphaltenes. See flocculation ratio.
3.2.1.1 Discussion—
SE is defined as FR multiplied by 100 %, as shown in Eq 2.
5/1
3.2.2 evaporation correction coeffıcient, n—the rate of evaporation of aromatic solvent (xylene) from the sample cup, measured
in grams per hour.
3.2.3 flocculation ratio (FR), n—the lowest aromatic solvent (xylene) concentration, expressed as a proportion of xylene to
xylene plus n-heptane which, when mixed with an oil, will not result in flocculation of asphaltenes. See 15.1, Eq 1.
3.2.4 FR , n—the flocculation ratio at a dilution of 5 mL of xylene and n-heptane solvent mixture to 1 g of oil.
5/1
3.2.4.1 Discussion—
The ratio 5 to 1 is used internally by a number of oil companies involved with the stability and compatibility of heavy fuel oils
and crude oils. This ratio is chosen so that a P-value of six represents an FR of zero.
5/1
3.2.5 insolubility number, I , n—a crude oil blending model parameter which can be used to determine if blends of oils are
N
compatible or incompatible. See solubility blending number.
3.2.5.1 Discussion—
Insolubility numbers for individual oils are determined and calculated from the density of the oil, aromatic solvent equivalent value
and volume of paraffinic solvent (n-heptane) that can be added to 5 mL of oil without asphaltene precipitation. The equations are
given under Calculation of Results (see 15.2).
3.2.6 maximum flocculation ratio, FR , n—of asphaltenes in residual fuel oils and crude oils, the minimum required solvency
max
power of a solvent mixture, expressed as a ratio by volume of aromatic solvent (xylene) to aromatic solvent plus paraffinic solvent
(n-heptane) to keep the asphaltenes in an oil colloidally dispersed.
D7112 − 19
3.2.6.1 Discussion—
FR is determined from a plot of flocculation ratios versus the oil concentration in solvent, extrapolated to infinite dilution of
max
the sample at the y-axis (where (1/X) = 0. See Eq 3).
3.2.7 oil matrix, 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 matrix (sometimes called an oil medium)
and asphaltenes.
3.2.8 P-value, n—of refinery residual steams, residual fuel oils and crude oils, an indication of the stability or available solvency
power of an oil with respect to precipitation of asphaltenes.
3.2.8.1 Discussion—
Since the equation defining P-value is P = (1 + X ), where X is the minimum volume of paraffinic solvent, n-heptane, (in mL)
min min
needed to be added to 1 g of oil to result in flocculation of asphaltenes, the smallest P-value is 1, which means the oil is unstable
and can precipitate asphaltenes without addition of any paraffinic solvent. A higher P-value indicates that an oil is more stable with
respect to flocculation of asphaltenes. P-value by this test method relates specifically to xylene and n-heptane as the aromatic and
paraffinic solvents, respectively.
3.2.9 P , n—the P-value of an asphaltene, which is the peptizability or ability of an asphaltene to remain colloidally dispersed.
a
3.2.10 P , n—the P-value of an oil matrix. See oil matrix.
o
3.2.11 peptize, v—of an oil or cutter stock, to dissolve an asphaltene or to maintain an asphaltene in colloidal dispersion.
3.2.12 solubility blending number, S , n—a crude oil blending model parameter which can be used to determine if blends of
BN
oils are incompatible or compatible. See insolubility number.
3.2.12.1 Discussion—
Solubility blending numbers for individual oils are determined and calculated from the density of the oil, aromatic solvent
equivalent value, and volume of paraffinic solvent that can be added to 5 mL of oil without asphaltene precipitation. The equations
are given under Calculation of Results (see 15.2).
3.2.13 step size, n—the volume in mL of each portion of n-heptane added to the stock solution in the course of the test
procedure.
3.2.14 stock solution, n—a solution of a sample dissolved in a specific amount of xylene.
3.3 Symbols:
FR = flocculation ratio
FR = flocculation ratio at a dilution of 5 mL solution (xylene plus n-heptane) to 1 g of oil
5/1
FR = maximum flocculation ratio
max
I = insolubility number
N
P = the P-value of an oil
P = the P-value of an asphaltene
a
P = the P-value or peptizing power of an oil matrix
o
S = solubility blending number
BN
SE = xylene equivalent, volume %
X = n-heptane consumption of undiluted oil, in mL/g of oil
min
4. Summary of Test Method
4.1 Stability and compatibility parameters are determined by titration and optical detection of precipitated asphaltenes. A stock
solution is prepared and three different mixtures of the sample oil plus xylene are titrated with n-heptane to cause precipitation of
asphaltenes. The titrated mixture is continuously circulated through an optical detector which detects precipitated asphaltenes by
back-scattering of visible light. The amounts of oil, xylene, and n-heptane are used to calculate stability parameters: solvent
equivalent, P-value, and FR . If the density of a crude oil sample is known, then the compatibility parameters (S and I ) of
5/1 BN N
the crude oil may also be calculated.
D7112 − 19
5. Significance and Use
5.1 Automatic determination of stability parameters using a light back-scattering technique improves accuracy and removes
human errors. In manual testing, operators have to visually compare oil stains on pieces of filter paper to determine if asphaltenes
have been precipitated.
5.2 Refinery thermal and hydrocracking processes can be run closer to their severity limits if stability parameters can be
calculated more accurately. This gives increased yield and profitability.
5.3 Results from the test method could be used to set a standard specification for stability parameters for fuel oils.
5.4 The compatibility parameters of crude oils can be used in crude oil blending in refineries to determine, in advance, which
crude oil blends will be compatible and thus can be used to minimize plugging problems, unit shut downs, and maintenance costs.
Determination of crude oil compatibility parameters also enables refineries to select crude oil mixtures more economically.
5.5 This test method can measure stability and compatibility parameters, and determine stability reserve on different blends for
particular applications to optimize the blending, storage, and use of heavy fuel oils
NOTE 1—Users of this test method would normally use stability and compatibility parameters to determine stability reserve of residual products, fuel
blends and crude oils. However, the interpretation of stability, stability reserve and compatibility is heavily ‘use dependent,’ and is beyond the scope of
this test method.
6. Interferences
6.1 Free water present in the oil can cause difficulties with the optical detector and should be removed by centrifuging prior to
testing.
6.2 Solid particles, such as coke or wax particles, mud, sand, or catalyst fines, in the oil will not affect the optical detector or
interfere with the results.
7. Apparatus
3,4
7.1 PORLA Heavy and Crude Oil Stability and Compatibility Analyzer —See Figs. 1 and 2.
7.1.1 A portion of the apparatus is shown diagrammatically in Fig. 2 and is comprised of the following parts:
7.1.1.1 Sample Cup, light weight, inert cups designed to fit the sample carousel, with a smooth, flat bottom, volume
approximately 100 mL. Typically, aluminum cups have been used.
7.1.1.2 Sample Carousel, typically a four-position sample cup holder delivering the sample cups sequentially to the
measurement position.
7.1.1.3 Mixer Lift System, vertically moving lift system, forming a seal with the sample cup in the measurement position and
incorporating a mechanical stirrer which starts to rotate when the seal is made. It also incorporates delivery lines for n-heptane and
xylene addition, the circulation line for passing the sample through the detector and the exhaust line, which empties the sample
cup after analysis.
7.1.1.4 Aromatic Solvent Pump, accurate and adjustable ceramic piston pump, capable of delivering xylene at a rate of
0.01 mL ⁄s to 0.5 mL/s.
7.1.1.5 Paraffınic Solvent Pump, accurate and adjustable ceramic piston pump, capable of delivering n-heptane at a rate of
0.01 mL ⁄s to 0.5 mL/s.
7.1.1.6 Circulation Pump, accurate and adjustable ceramic piston pump used to circulate the sample under test through the
detector system.
7.1.1.7 Exhaust Pump, accurate and adjustable ceramic piston pump used to empty the sample cup at the end of the
measurement.
7.1.1.8 Detector System, (see Fig. 3) optical detector through which the sample solution is continuously circulated. The detector
is composed of a visible light source and a photodiode for recording the light reflecting from asphaltene particles in the test sample.
7.1.1.9 Hot Plate, a temperature controlled heating system may be located below the sample cups, which will warm up the
sample so that the titration may be performed at an elevated temperature. The temperature of the hot plate should be adjustable
between 20 °C and 100 °C.
7.1.2 Computer, controls the measurement and calibration programs and is an interface between the operator and the analyzer.
7.1.3 PORLA Step Measurement Screen, computer display, allowing data about the sample and operator to be input as well as
showing the results of each titration (see Fig. 4).
The PORLA Heavy and Crude Oil Stability and Compatibility Analyzer is covered by Euro patent EP 0737309 and U.S. patent US5715046. Interested parties are invited
to submit information regarding the identification of an alternative(s) to this patented item to the ASTM International Headquarters. Your comments will receive careful
consideration at a meeting of the responsible technical committee, which you may attend.
The sole source of supply of the PORLA Heavy and Crude Oil Stability and Compatibility Analyzer known to the committee at this time is Finnish Measurement Systems
Limited, Koskikuja 5, FIN-71570 Syvanniemi, Finland,
www.finnmeassys.com. 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.
D7112 − 19
FIG. 1 PORLA Heavy and Crude Oil Stability and Compatibility Analyzer
7.1.4 Parameter Screen, computer display, allows all of the measurement cycle parameters to be adjusted from the default
values and also allows the pump calibration procedure to be run (see Fig. 5).
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, all reagents shall
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 determined that the reagents are of sufficiently high
purity to permit their use without lessening the accuracy of the determination.
8.2 Xylene (C H )—The xylene used is generally a mixture of ortho, meta, and para isomers and may contain some ethyl
8 10
benzene. (Warning—Flammable, health hazard.)
8.3 n-heptane (C H )—(Warning—Flammable, health hazard.)
7 16
9. Hazards
9.1 Place the analyzer in a fume hood or similar well ventilated area to minimize exposure of operators to harmful vapors.
Reagent Chemicals, American Chemical Society Specifications, 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.
D7112 − 19
FIG. 2 Schematic Diagram of PORLA Heavy and Crude Oil Stability and Compatibility Analyzer
FIG. 3 Schematic Diagram of PORLA Heavy and Crude Oil Stability and Compatibility Analyzer Detector
9.2 Operators should use proper protective laboratory clothing and gloves to avoid skin exposure to oil samples and solvents.
In addition, operators should be careful when handling hot oil containers when preparing the stock solutions from very viscous
oils as oil spills on exposed skin will cause burns.
10. Sampling and Test Specimens
10.1 Obtain samples in accordance with procedures described in Practices D4057 or D4177. Ensure that samples are
representative of the whole batch of oil.
10.2 A minimum sample size of 40 g is required for a single test. It is preferable to collect a larger sample such as 200 g to 500 g
to allow for multiple testing, if necessary.
10.3 Ensure that the sample is homogeneous before withdrawing an aliquot or test specimen for testing.
D7112 − 19
FIG. 4 PORLA Step Measurement Screen
10.4 To avoid changes or degradation of oil samples, minimize exposure to air, temperatures above 25 °C, and light. Store
samples in sealed, opaque containers such as metal cans or dark glass bottles.
11. Preparation of Apparatus
11.1 Review the operations manual for the apparatus, and follow all recommended steps. The following actions summarize the
preparation of the apparatus:
11.1.1 Place the apparatus on a level surface, in a well-ventilated area such as a fume hood.
11.1.2 Connect the analyzer and the computer to a suitable ac power source, and connect the analyzer, keyboard, monitor, and
mouse to the computer with the cables supplied.
NOTE 2—All of the controls for the instrument except for the main power switch are accessed by means of the keyboard and mouse of the computer.
11.1.3 Fill the aromatic and paraffinic solvent bottles with xylene and n-heptane, respectively, and ensure the waste bottle is
empty. Connect the three plastic bottles, labeled aromatic solvent, paraffinic solvent and waste, to the appropriate lines from the
analyzer.
11.1.4 Switch the analyzer on using the rocker switch on the back panel. A green lamp will illuminate on the upper right of the
front panel.
11.1.5 Switch on the computer and allow it to boot up.
11.1.6 Select either PORLA Step or PORLA Test by double clicking the mouse on the appropriate icon to bring up the PORLA
Step measurement screen (see Fig. 4) or the system test screen.
12. Calibration and Standardization
12.1 Pump Calibration—Perform the pump calibration at the initial set-up and whenever the instrument has been serviced.
When in continuous service, perform pump calibrations monthly to verify the pumping rates.
Obtain the operator’s manual from the supplier of the apparatus.
D7112 − 19
FIG. 5 PORLA Parameter Screen
12.1.1 On the PORLA Step measurement screen (Fig. 4) select the Parameter screen (see Fig. 5). Calibrate the xylene and
n-heptane pumps by starting the automatic procedure under Pump Calibration.
12.1.2 Identify two clean sample cups as ‘xylene’ and ‘n-heptane,’ and accurately weigh to two decimal places. These are the
tare weights of the cups.
12.1.3 The instrument automatically pumps solvent ov
...