ASTM D4177-22e1

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.
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Designation: D4177 − 22
Manual of Petroleum Measurement Standards (MPMS), Chapter 8.2
Standard Practice for
Automatic Sampling of Petroleum and Petroleum Products
This standard is issued under the fixed designation D4177; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—Added adjunct information editorially in March 2023.
INTRODUCTION
The previous version of the automatic sampling practice described the design, installation, testing,
and operation of automated equipment for the extraction of representative samples from the flowing
stream and storing mainly for crude oil.
This practice is a performance-based standard. It still includes the design, installation, testing, and
operation of automated equipment for extraction of representative samples. It also includes the testing
and proving of a sampling system in the field under actual operating conditions to ensure that the
equipment, installation, and operating procedures produce representative samples. The acceptance
criteria for custody transfer are covered in this practice. This practice does not address how to sample
crude at temperatures below the freezing point of water. Extensive revisions have been made to the
prior version of D4177 (API MPMS Chapter 8.2).
This practice also provides guidance for periodic verification of the sampling system.
This practice is separated into three parts:
General—Sections 5 – 17 (Part I) are currently applicable to crude oil and refined products. Review
this section before designing or installing any automatic sampling system.
Crude Oil Sampling—Section 18 (Part II) contains additional information required to complete the
design, testing, and monitoring of a crude oil sampling system.
Refined Product Sampling—Section 19 (Part III) contains additional information required to
complete the design of a refined product sampling system.
A representative sample is “A portion extracted from the total volume that contains the constituents
in the same proportions that are present in that total volume.” Representative samples are required for
the determination of chemical and physical properties that are used to establish standard volumes,
prices, and compliance with commercial and regulatory specifications.
The process of obtaining a representative sample consists of the following: the physical equipment,
the correct matching of that equipment to the application, the adherence to procedures by the
operator(s) of that equipment, and the proper handling and analysis.
1. Scope*
1 1.1 This practice describes general procedures and equip-
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum
Products, Liquid Fuels, and Lubricants and the API Committee on Petroleum ment for automatically obtaining samples of liquid petroleum
Measurement, and is the direct responsibility of Subcommittee D02.02 /COMQ the
and petroleum products, crude oils, and intermediate products
joint ASTM-API Committee on Hydrocarbon Measurement for Custody Transfer
from the sample point into the primary container. This practice
(Joint ASTM-API). This practice has been approved by the sponsoring committees
and accepted by the Cooperating Societies in accordance with established proce- also provides additional specific information about sample
dures. This practice was issued as a joint ASTM-API standard in 1982.
container selection, preparation, and sample handling. If sam-
Current edition approved July 1, 2022. Published August 2022. Originally
pling is for the precise determination of volatility, use Practice
approved in 1982. Last previous edition approved in 2020 as D4177 – 20. DOI:
10.1520/D4177-22E01. D5842 (API MPMS Chapter 8.4) in conjunction with this
*A Summary of Changes section appears at the end of this standard
© Jointly copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA and the American Petroleum Institute (API), 1220 L Street NW, Washington DC 20005, USA
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D4177 − 22
practice. For sample mixing and handling, refer to Practice 2. Referenced Documents
D5854 (API MPMS Chapter 8.3). This practice does not cover 2
2.1 ASTM Standards:
sampling of electrical insulating oils and hydraulic fluids.
D4007 Test Method for Water and Sediment in Crude Oil by
the Centrifuge Method (Laboratory Procedure)
1.2 Table of Contents:
D4057 Practice for Manual Sampling of Petroleum and
Section
Petroleum Products
INTRODUCTION
Scope 1
D4175 Terminology Relating to Petroleum Products, Liquid
Referenced Documents 2
Fuels, and Lubricants
Terminology 3
D4840 Guide for Sample Chain-of-Custody Procedures
Significance and Use 4
PART I–GENERAL
D4928 Test Method for Water in Crude Oils by Coulometric
Representative Sampling Components 5
Karl Fischer Titration
Design Criteria 6
D5842 Practice for Sampling and Handling of Fuels for
Automatic Sampling Systems 7
Sampling Location 8
Volatility Measurement
Mixing of the Flowing Stream 9
D5854 Practice for Mixing and Handling of Liquid Samples
Proportionality 10
of Petroleum and Petroleum Products
Sample Extractor Grab Volume 11
Containers 12
2.2 ASTM Adjuncts:
Sample Handling and Mixing 13
Sampling Frequency and Sampling System Monitoring
Control Systems 14
Sample System Security 15
Spreadsheet
System Proving (Performance Acceptance Tests) 16
Performance Monitoring 17 2.3 API Standards:
PART II–CRUDE OIL
MPMS Chapter 1 Vocabulary
Crude Oil 18
MPMS Chapter 3 Tank Gauging
PART III–REFINED PRODUCTS
Refined Products 19 MPMS Chapter 4 Proving Systems
KEYWORDS
MPMS Chapter 5 Metering
Keywords 20
MPMS Chapter 8.1 Standard Practice for Manual Sampling
ANNEXES
Calculations of the Margin of Error based on Number of Annex A1
of Petroleum and Petroleum Products (ASTM Practice
Sample Grabs
D4057)
Theoretical Calculations for Selecting the Sampler Probe Annex A2
MPMS Chapter 8.3 Practice for Mixing and Handling of
Location
Portable Sampling Units Annex A3
Liquid Samples of Petroleum and Petroleum Products
Profile Performance Test Annex A4
(ASTM Practice D5854)
Sampler Acceptance Test Data Annex A5
MPMSChapter 8.4 Practice for Manual Sampling and Han-
APPENDIXES
Design Data Sheet for Automatic Sampling System Appendix X1
dling of Fuels for Volatility Measurement (ASTM Practice
Comparisons of Percent Sediment and Water versus Appendix X2
D5842)
Unloading Time Period
MPMS Chapter 10 Sediment and Water
Sampling Frequency and Sampling System Monitoring Appendix X3
Spreadsheet
MPMS Chapter 13 Statistical Aspects of Measuring and
Sampling System Monitoring—Additional Diagnostics Appendix X4
Sampling
1.3 Units—The values stated in either SI units or US MPMS Chapter 20 Production Allocation Measurement for
Customary (USC) units are to be regarded separately as High Water Content Crude Oil Sampling
standard. The values stated in each system may not be exact MPMS Chapter 21 Flow Measurement Using Electronic
equivalents; therefore, each system shall be used independently Metering Systems
of the other. Combining values from the two systems may
2.4 ISO Standards:
result in non-conformance with the standard. Except where
ISO 1998 Petroleum Industry – Terminology – Part 6:
there is no direct SI equivalent, such as for National Pipe
Measurement
Threads/diameters, or tubing.
NOTE 1—See the Bibliography at the end of this standard for important
1.4 This standard does not purport to address all of the historical references.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
mine the applicability of regulatory limitations prior to use. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
1.5 This international standard was developed in accor-
the ASTM website.
dance with internationally recognized principles on standard-
Available from ASTM International Headquarters. Order Adjunct No.
ADJD4177-EA. Original adjunct produced in 2020.
ization established in the Decision on Principles for the
Available from American Petroleum Institute (API), 200 Massachusetts Ave.
Development of International Standards, Guides and Recom-
NW, Suite 1100, Washington, DC 20001, http://www.api.org.
mendations issued by the World Trade Organization Technical 5
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
Barriers to Trade (TBT) Committee. 4th Floor, New York, NY 10036, http://www.ansi.org.
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D4177 − 22
3. Terminology 3.2.14 slip stream take-off probe, n—device, inserted into
the flowing stream, which directs a representative portion of
3.1 Definitions:
the stream to a slip stream sample loop.
3.1.1 For definitions of terms used in this practice, refer to
Terminology D4175 and API MPMS Ch 1. 3.2.15 volume regulator sampler, n—device that allows
3.2 Definitions of Terms Specific to This Standard: pipeline pressure to push a set volume into a chamber that is
3.2.1 automatic sampling system, n—fluid sampling system then trapped and redirected to the sample container.
that consists of: (a) flowing fluid stream conditioning, if
3.3 Definitions Related to Sample Containers:
required; (b) a means of automatically extracting a represen-
3.3.1 constant volume sample container, n—vessel with a
tative sample; (c) pacing of the sample extraction in a flow or
fixed volume.
time proportional manner; and (d) delivering of each extracted
3.3.2 floating piston container, FPC, n—high-pressure
sample to a sample container or an analyzer.
sample container, with a free floating internal piston that
3.2.1.1 Discussion—The system consists of a sample extrac-
effectively divides the container into two separate compart-
tor with an associated controller and flow-measuring or timing
ments.
device, collectively referred to as an automatic sampler or
auto-sampler. In addition, the system may include a flow 3.3.3 portable sample container, n—vessel that can be
conditioner, slipstream, sample probe, and sample condition-
manually transported.
ing.
3.3.4 primary sample container, n—container in which a
3.2.1.2 Discussion—Systems may deliver the sample di-
sample is initially collected, such as a glass or plastic bottle, a
rectly to an analytical device or may accumulate a composite
can, a core-type thief, a high-pressure cylinder, a floating
sample for offline analysis, in which case, the system includes
piston cylinder, or a sample container in an automatic sampling
sample mixing and handling and a primary sample container.
system.
3.2.1.3 Discussion—Automatic sampling systems may be
3.3.5 profile average, n—in sampling, the average of all
used for liquids.
point averages.
3.2.2 batch, n—discrete shipment of commodity defined by
3.3.6 profile testing, n—procedure for simultaneously sam-
a specified quantity, a time interval, or quality.
pling at several points across the diameter of a pipe to identify
3.2.3 component testing, n—process of individually testing
the extent of cross-sectional stratification.
the components of a system.
3.3.7 representative sample, n—portion extracted from a
3.2.4 dead volume, n—in sampling, the volume trapped
total volume that contains the constituents in the same propor-
between the extraction point and the primary sample container.
tions that are present in that total volume.
3.2.4.1 Discussion—This represents potential for contami-
nation between batches. 3.3.8 sample, n—portion extracted from a total volume that
may or may not contain the constituents in the same propor-
3.2.5 droplet dispersion, adj—degree to which a fluid in an
tions as are present in that total volume.
immiscible fluid mixture is composed of small droplets distrib-
uted evenly throughout the volume of the pipe. 3.3.9 sample probe, n—device extending through the meter
tube or piping into the stream to be sampled.
3.2.6 flow-proportional sample, n—sample taken from a
pipe such that the rate of sampling is proportional throughout
3.3.10 sampling, n—all the steps required to obtain a sample
the sampling period to the flow rate of the fluid in the pipe.
that is representative of the contents of any pipe, tank, or other
vessel, based on established error and to place that sample into
3.2.7 free water, n—water that exists as a separate phase.
a container from which a representative test specimen can be
3.2.8 grab, n—volume of sample extracted from a flowing
taken for analysis.
stream by a single actuation of the sample extractor.
3.3.11 sampling system, n—system capable of extracting a
3.2.9 homogeneous, adj—quality of being uniform with
representative sample from the fluid flowing in a pipe.
respect to composition, a specified property or a constituent
3.3.11.1 Discussion—system capable of extracting a repre-
throughout a defined area or space.
sentative sample from the fluid flowing in a pipe. (ISO 1998-6)
3.2.10 linefill, n—volume of fluid contained between two
3.3.12 sampling system verification test, n—procedure to
specified points in piping or tubing.
establish that a sampling system is acceptable for custody
3.2.11 sample controller, n—device used in automatic sam-
transfer.
pling that governs the operation of a sample extractor.
3.3.13 secondary sample container, n—vessel that receives
3.2.12 sample extractor, n—in sampling, a mechanical de-
an aliquot of the primary sample container for the purpose of
vice that provides for the physical measured segregation and
analysis, transport, or retention.
extraction of a grabbed sample from the total volume in a
3.3.14 stationary sample container, n—vessel that is physi-
pipeline, slip stream, or tank and ejects the sample towards the
primary sample container. cally fixed in place.
3.2.13 slip stream sample loop, n—low-volume stream di- 3.3.15 stream conditions, n—state of a fluid stream in terms
verted from the main pipeline, intended to be representative of of distribution and dispersion of the components flowing
the total flowing stream. within the pipeline.
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D4177 − 22
3.3.16 stream conditioning, n—mixing of a flowing stream 5.1.6 System Performance Verification—Perform test(s) to
so that a representative sample may be extracted. verify the system is performing in accordance with the criteria
set forth within this practice or as otherwise agreed.
3.3.17 time-proportional sample, n—sample composed of
5.1.7 Performance Monitoring—Provide performance mea-
equal volume grabs taken from a pipeline at uniform time
surement and recording of the sampling system to validate that
intervals during the entire transfer.
the system is operating within the original design criteria and
compatible with the current operating condition.
4. Significance and Use
4.1 Representative samples of petroleum and petroleum
6. Design Criteria
products are required for the determination of chemical and
physical properties, which are used to establish standard 6.1 The following items shall be addressed when designing
a sampling system:
volumes, prices, and compliance with commercial terms and
regulatory requirements. This practice does not cover sampling
6.1.1 Volume of sample required for analysis and retention;
of electrical insulating oils and hydraulic fluids. This practice
6.1.2 Conditions (temperature, pressure, viscosity, density,
does not address how to sample crude at temperatures below
minimum and maximum flow rates, sediment, water, and
the freezing point of water.
contaminants);
6.1.3 Type of fluid (crude oil, gasoline, diesel, kerosine, or
PART I—General
aviation fuel);
This part is applicable to all petroleum liquid sampling
6.1.4 Grabs per Batch—Ensure the sample extractor(s)
whether it be crude oil or refined products. Review this section
samples at a high enough frequency to obtain the required
before designing or installing any automatic sampling system.
number of grabs without exceeding the limits of the equipment
or other sampling system constraints. Increasing the number of
5. Representative Sampling Components
grabs taken per batch reduces sampling uncertainty as de-
5.1 The potential for error exists in each step of the
scribed in Annex A1. For large custody transfer batch
sampling process. The following describes how sampling
quantities, to ensure representativeness of the total volume of
system components or design will impact whether the sample
extracted sample in the sample container, some operators have
is representative. Properly address the following considerations
set an expectation that is equivalent to a margin of error of 0.01
to ensure a representative sample is obtained from a flowing
with 95 % confidence. Eq A1.6 calculates this to be 9604 grabs
stream.
per batch. In practice, a rounded up recommended value of
5.1.1 Location—Locate the sampling system close to or at a
10 000 grabs per batch is often used in industry. Small batch
position where the custody transfer is deemed to have taken
sizes, small capacity of the primary sample container and other
place. The quality and quantity of the linefill between the
sampling system constraints may result in designs with a
extractor and the sample container may be significant enough
different design criterion than 9604 grabs per batch. For
to impact the quality of the sample.
additional information on refined product sampling, refer to
5.1.2 Conditioning of the Flowing Stream—Disperse and
Section 19.
distribute (homogenize) the sample stream at the sample point
6.1.4.1 The margin of error refers to use of a statistic
so that the stream components (for example oil, water, and
computed from a random sampling of the population to
sediment) are representative at the point of the slip stream
estimate the true but unknown population parameter of interest.
sample loop inlet (if used) or where the sample is to be
This margin of error is quantified by the width of the
extracted.
confidence interval constructed using the numerical value of
5.1.3 Sample Extraction—Take grabs in proportion to flow.
the statistic, the random sample size, and a user-specified
However, if the flow rate during the total batch delivery (hours,
confidence that the true value for the population parameter is
days, week, month, and so forth) varies less than 610 % from
captured somewhere in the confidence interval. Margin of error
an average flow rate, and if the sampling stops when the flow
is not intended to be applied to measurements related to the
stops, a representative sample may be obtained by the time
quality of the sample and its tested properties.
proportional control of the sampling process.
6.1.4.2 When a process system is designed to control the
5.1.4 Sample Containers—The sample container shall be
material production to meet specification, such as the case with
capable of maintaining the sample’s integrity, which includes
finished products and material that is controlled in production
not altering the sample composition. Minimize the venting of
or a blending process, refer to Section 19 for additional
hydrocarbon vapors during filling and storage and protect the
guidance on margin of errors versus number of grabs.
sample container from adverse ambient elements. The sample
container should also be compatible with the fluid type to avoid
NOTE 2—When sampling small batch sizes of refined products, all
degradation of the sample container and possible leakage of the affected parties should agree to and recognize the margin of error
associated with the number of sample grabs at an agreed upon confidence
sample.
level.
5.1.5 Sample Handling and Mixing—Provide a means to
allow the sample to be made homogenous before extraction of 6.1.5 Batch Size(s)/Duration—Ensure the sample extrac-
aliquots for analysis, retention, or transportation. For more tor(s) samples at a high enough frequency to obtain the
information regarding the handling and mixing of samples, required sample volume without exceeding the limits of the
refer to Practice D5854 (API MPMS Chapter 8.3). equipment;
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6.1.6 Homogeneity of the Fluid/Stream Conditioning— 6.1.21 Locating the opening of the sample probe in the part
Ensure the pipeline content is homogeneous at the point of of the flowing stream where the fluid is representative;
extraction (sample point) over the entire flow range of all 6.1.22 Locating the opening of the sample probe in the
anticipated product types. Give special consideration to direction of the flow;
viscosity, density, and vapor pressure; 6.1.23 Ensuring the fluid entering the sample probe tip
6.1.7 Consider the interface between batches; follows a path that creates no bias;
6.1.24 Ensuring that the fluid from the extractor flows into
6.1.8 Consider incorporating additional analyzers in the
the primary sample container;
sampling system design that would provide for valuable
6.1.25 Ensuring all of the samples taken during the batch go
feedback with regards to the stream being sampled;
into the primary sample container, the sample container con-
6.1.9 Consider the failure and maintenance of any devices
tents are properly mixed, and any portion extracted for analysis
inserted directly into the process pipeline and their ability to
is representative; and
withstand pressure surges. Additionally, consider bending mo-
6.1.26 Ensuring that good sampling and handling proce-
ment and vibrations caused by flow-induced vortices that the
dures are followed to maintain representativeness at each stage
devices may encounter;
of the mixing, distribution, and handling of the sample from
6.1.10 Consider the interconnection between the sample
point of first receipt into the primary sample container to its
extractor and the primary sample container to ensure the
analysis.
sample remains representative of the batch;
6.1.11 Provide a flow measurement device or a method to
6.2 Other Considerations:
provide a flow signal for flow proportioning the sampling
6.2.1 High Reid Vapor Pressure (RVP) Fluids (Examples
system. The flow proportioned approach allows for a represen-
are Crude and Condensate)—Where the crude oil or crude
tative sample with varying flow rates encountered over the
condensate has a RVP greater than 96.53 kPa, the process and
duration of a batch. The frequency of sample grabs is in
practicalities of handling and transporting large pressurized
proportion to the flow rate in the process.
(constant pressure) containers precludes the possibility of
taking 9604 grab samples. A practical expectation for handling
NOTE 3—Varying flow rates may be due to normal process startup,
is normally 1 L to 4 L. Systems and processes that yield
process production changes, process shutdown, external factors, etc.
samples based on less than 9604 grabs should be established
6.1.12 The time proportioned approach allows for a repre-
and agreed between all interested parties.
sentative sample only if the flow rate does not vary (see 5.1.3)
6.2.2 Representative Sample—Sample Extractor to
for the duration of a batch. The frequency of sample grabs does
Container—Sample grabs are extracted from the flowing pipe
not change throughout the batch.
by the sample extractor. At the beginning of each batch, the
NOTE 4—Applying time proportional sampling with flow rates that vary volume retained in the internal mechanism of the sampling
more than 6 10 % from the average flow rate (see 5.1.3) will not deliver
device or tubing between the sample extractor and sample
a representative sample.
container may contaminate the properties of the subsequent
6.1.13 Ensure the tubing from the sample probe or extractor batch if not properly displaced. This may be minimal where the
to the sample container slopes continuously downward towards sampling process is measuring identical products in sequential
the sample container point of entry; batches belonging to a common owner. However, where
sequential batches may possess significantly different
6.1.14 Provide a control system (which may include an
overall supervisory reporting system (Human-machine Inter- properties, be different types of refined products or be of
differing ownership, the volume between the point of sample
face (HMI)/Supervisory Control and Data Acquisition
(SCADA))) to operate the sample system in proportion to flow; extraction and the sample container has the potential to
produce non-representative samples. These non-representative
6.1.15 Use performance monitoring equipment to verify
samples can impact the integrity of the custody transfer and
that samples are being taken in accordance with the sampling
volumetric reconciliations of each batch transferred and may
system design and this practice;
also result in unwarranted product quality concerns. Consider
6.1.16 Provide environmental protection that may consist of
the evaluation of this interface and minimize the dead volume.
a building, enclosure, or shelter and heating or cooling sys-
Purging with alternate fluids, air, or inert gas has the potential
tems. Heating may impact the electrical certification. It may be
to displace this linefill into the proper sample container, but
necessary to install parts or all of the sampling system in heated
exercise caution to ensure that other quality properties of the
(or cooled) or enclosed environments to maintain the integrity
sample are not impacted. A sampling system capable of
of the samples taken, sample handling, or reduce the incidence
purging through the sampling container and using multiple
of mechanical failure, for example, caused by increased
containers may also be an alternative.
viscosity or wax content. Safety protections in regard to static
electricity and flammable vapors when sampling shall also be
7. Automatic Sampling Systems
considered;
6.1.17 Consider sample system integrity and security;
7.1 Automatic sampling systems may be fixed or portable
6.1.18 Ensure all applicable regulatory requirements are
and are divided into two types: in-line or slip stream sample
met;
loop. Each system design has a sample extraction mechanism
6.1.19 Consider the properties of interest to be analyzed;
that isolates a sample from the stream. The sample extractor
6.1.20 Extracting samples in proportion to flow or time; can be within the flowing stream or mounted offset as in the
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D4177 − 22
case of a volume regulator (Fig. 3). When a fixed system is not 7.3.2 Avoid blockage in the slip stream sample loop or
practical, the use of portable designs may be considered, see pressure pulses created by sample extractors. See Fig. 2. For
Figs. 1 and 2. more information on crude oil design characteristics, refer to
18.4.
7.2 In-line Sampling Systems—An in-line sampling system
places the sampling extraction mechanism or the take-off probe 7.4 Portable Sampling Systems—Portable samplers are
of a volume regulator sampler directly within the flowing those that may be moved from one location to another. The
stream. See Fig. 1 and Fig. 3. requirements for obtaining a representative sample with a
portable sampler are the same as those of a fixed sampling
7.3 Slip Stream Sample Loop System—A slip stream sample
system.
loop system has a take-off probe located in the main pipeline
7.4.1 In crude oil, fuel oil, or product sampling applications,
that directs a portion of the fluid flow into the slip stream
a typical application of a portable sampling system is on board
sample loop (see Fig. 2) and past a sample extractor or the
at the manifold of a marine vessel or barge. There are also
take-off probe of a volume regulator sampler (see Fig. 3).
occasional applications on shore.
7.3.1 Give consideration to the following aspects involving
7.4.2 The same design criteria for representative sampling
the take-off probe placement and design to prevent stratifica-
apply to both portable and stationary sampling systems. An
tion or separation of the hydrocarbon stream components or
example of portable samplers is shown in Fig. 4.
significant lag time:
7.3.1.1 The opening size;
8. Sampling Location
7.3.1.2 Forward facing; and
7.3.1.3 Sufficient velocity through interconnecting piping, 8.1 System Location—The optimal location for installation
sample extractor or analyzers, and slip stream sample loop of the sampling system is to be as close as possible to the
system. custody transfer point. Consideration should be given to
FIG. 1 In-Line Sampling System
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FIG. 2 Slip Stream Sample Loop Sampling System
FIG. 3 Sample Volume Regulator
onshore, offshore, shipboard, tanker, rail car, loading arm 8.2 Sample Take-Off Probe Location—For sample extractor
installations, and linefill issues that may impact the location, probes or sample take-off probes, to prevent the sample from
geography, or environmental restrictions, and other possible being misrepresentative of the flowing line, insert the sample
locations. It may not be practical to place the system close to probe in the center half of the flowing stream. Verify that the
this optimal position; therefore, minimize the distance from the probe is installed correctly, the probe opening is facing in the
system to the custody transfer point. See Fig. 5. desired appropriate direction for the application, and the
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D4177 − 22
FIG. 4 Typical Portable Installation
FIG. 5 Linefill
external body of the probe is marked with the direction of flow. 8.2.4 When possible, the preferred orientation of the extrac-
See Fig. 6 (probe design).
tor probe is horizontal.
8.2.1 The sample probe shall be located in a zone in which
8.2.5 Use a sample take-off probe of sufficient strength to
sufficient mixing results in adequate stream conditioning (see
resist the bending moments and vortices that may be created
19.2).
across the full process range.
8.2.2 The recommended sampling area is approximately the
8.3 Sample Extractor Location—The position and design of
center half of the flowing stream as shown in Fig. 7.
8.2.3 When a main line mixing device is used, the manu- the extractor within the piping cross section may be influenced
facturer shall be consulted for the sample probe’s optimum by the basic properties of the product being sampled. Design
location with regard to downstream distance and piping.
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D4177 − 22
FIG. 6 Probe Design
FIG. 7 Sample Probe and Slip Stream Take-Off Probe Location for Vertical or Horizontal Pipe
and install the extractor in the pipeline in a position so that it 8.4.2 Linefill is a known or estimated volume and requires
minimizes any change to the properties of the sample as it is special consideration as part of cargo transfer calculations and
withdrawn. procedures. The simplest example is one ship or tank and one
8.3.1 Install the probe in a position on the cross section pipeline. Consider the volume of the batch to be sampled
considered as representative. Insertion of the probe within the between the take-off point and the transfer position, which is
center half of the flowing stream see Fig. 7 meets the criteria. known as linefill. The influence of the properties of interest in
8.3.2 If stream conditioning has been used to improve the relation to the overall batch volume may be significant enough
homogeneity at the sample position, install the sample extrac- to alter the composite sample.
tor in the optimal position downstream. The recommended
distance downstream will be supplied by the stream condi- 9. Mixing of the Flowing Stream
tioner manufacturer.
9.1 Stream Conditioning:
8.3.3 Use an extractor probe of sufficient strength to resist
9.1.1 Stream conditioning increases the level of turbulence
the bending moments and vortices that may be created across
by using additional energy. Ensure that, at the point of
the full process range.
sampling the fluid is homogenous so that, when the fluid is
8.4 Linefill Considerations—When the transfer happens, tested, the test result is representative of the entire stream.
when the receipt point and sample point are a substantial When there is not adequate turbulence, additional efforts are
distance apart such as in excess of a mile away from the meters required to condition the stream so that it will be representative
and sampling system, the linefill between the receipt point and at the point of sampling.
the sampling system will not be sampled until the next 9.1.2 Hydrocarbon fluids containing a denser phase product
movement occurs. Account for the linefill at a later date when (that is, water, sediment, or both) will require energy to
the volume is displaced. See Fig. 5 (linefill). disperse the contaminants within the flowing stream. Refined
8.4.1 Linefill—The linefill portion of a parcel may be petroleum products and non-crude feed stocks, such as
handled in a variety of ways. Some line fills are pushed the naphtha, are generally homogeneous and usually require no
final distance using water or inert gas. This clears the pipeline special stream conditioning. Exceptions include when free
of the batch and samples the last few cubic metres (bbl) of the water, sediment, or unique contaminants are present or if a
parcel into the same sample container. nonhomogeneous product is being sampled.
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9.1.3 Stream conditioning is impacted by upstream piping metering streams. Additionally, flow patterns within headers
elements such as elbows and valves. These elements can are unpredictable and impacted by the number and order of
promote mixing but may also skew the flow profile. Piping streams in service. The sampling system may be located
elements can be installed that are specifically designed to upstream or downstream of the metering system. If the velocity
develop a homogenous stream. Other elements can be installed of the product in the pipe at the sample point does not provide
to add energy to the stream, increasing turbulence. adequate homogeneity for sampling (under worst-case flow
and product conditions), the system requires additional stream
9.2 Stream Conditions:
conditioning. (For water-in-oil sampling, see C1/C2 calcula-
9.2.1 When assessing whether stream conditions require
tions in Annex A2 for further guidance around mixing.)
that additional measures be taken to ensure adequate mixing,
9.4.3 Stream Blending—Ensure automatic sampling systems
consider the following, in each case considering the worst-case
are sufficiently downstream of points where different streams
conditions:
are blended to enable thorough mixing to occur.
9.2.1.1 Velocity of the Flowing Stream—It is most difficult
to ensure representative sampling at low-stream velocities. If 10. Proportionality
an in-line mixing element is installed, pressure drops will
10.1 An automatic sampling system controller paces a
increase as the stream velocity increases potentially resulting in
sampling device to extract representative samples throughout a
unacceptable pressure drops across the mixing element. For
batch or period. The proportionality of the samples being
streams at or near their bubble point, pressure drops across the
extracted can be defined by the following categories:
mixing element may lead to phase separation.
10.1.1 Flow-Proportional Sampling:
9.2.1.2 Water Content—It is more difficult to sample
10.1.1.1 Custody Transfer Meters—Use custody transfer
streams with higher water contents because water droplets in
meters to pace the sampler where available. When using a
the emulsion tend to be larger and slugging of the water can
single sampling point and measuring flow by multiple meters,
occur.
pace the sampler by the combined total flow signal. In some
circumstances, install a separate sampling system in each meter
9.3 Methods of Stream Conditioning:
run. In this case, pace the sampler by the meter it is supporting
9.3.1 Base Case Stream Properties—Some streams are suf-
(API MPMS Chapter 5).
ficiently homogenized because of the fluid properties and
10.1.1.2 Special Flow Rate Indicators—Automatic tank-
velocity so that additional stream conditioning is not required.
gauging system for custody transfer may pace the sampling
9.3.2 Upstream Piping Elements—Thoughtful selection of
system in proportion to flow API MPMS Chapter 3.
the location of the sampling point can improve the chances of
10.1.1.3 An add-on flow metering device such as a
a well-mixed stream. Harnessing the impact of upstream
clamp-on meter may be able to pace the sampling in proportion
elements such as valves, tees, elbows, flow meters, reducers,
to flow.
air eliminators, or pumps can enhance mixing of the flowing
10.1.2 Time-Proportional Sampling—Sampling in a time-
stream. To be effective, the sample point needs to be located in
proportional mode is acceptable if the flow rate variation is less
close proximity to selected upstream elements. The effective-
than 610 % of the average rate over the entire batch and if the
ness of this approach in generating a homogenous stream is not
sampling stops when the flow stops.
assured in any case and may not be adequate for all stream
conditions.
10.2 Care shall be taken not to sample faster than either the
9.3.3 Static Mixer—A device that uses the kinetic energy of
sample extractor or the sample control system is capable of
the moving fluid to achieve stream conditioning by placing a operating. Operating a sampling system in this manner will
series of internal obstructions in the pipe designed to mix and
result in a non-representative sample.
evenly distribute all stream components throughout the pipe
11. Sample Extractor Grab Volume
cross section.
11.1 Sample extractors extract a wide variety of volumes
9.3.4 Power Mixer—Power mixing systems use an external
per sample grab. When designing the sample system, consider
energy source; typically, an electric motor or pump to increase
the extractor grab volume and the container volume. The
fluid velocity and turbulence.
extraction of larger volumes per grab may require a larger
9.4 Location of Automatic Sampling System:
container to accommodate the number of grabs per batch. For
9.4.1 General—An automatic sampling system should be
non-homogeneous (for example, crude) applications, see An-
located in a position that best guarantees access to a homoge-
nex A1 to calculate the margin of error depending on the
neous stream. Consideration should be given to using any
number of grabs.
mixing benefits of upstream elements and avoiding partially
11.2 Larger grab volumes may also be required to fill a
filled pipes, dead legs, or headers.
container to an acceptable level per Practice D5854 (API
9.4.2 Multiple Run Metering Systems and Headers—When
MPMS Chapter 8.3) during small-volume batches delivered at
a sampling system is used in conjunction with a multiple-run
high flow rates. For the same overall volume collected, larger
metering system, the sample point should not be located on an
sample grab volumes will reduce the sample frequency and
individual meter run, inlet, or outlet header. For example, a
also the resolution of the sample.
horizontal pipeline carrying crude oil and water will, at low
flow rate, have the potential for stratification resulting in free 11.3 Sample grab volumes should be repeatable within
water, which is likely to be divided unevenly between the 65.0 %. The nominal grab volume (as determined by the
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sample probe manufacturer) is not necessarily the same as the 12.1.4 Both the design and materials of a sample container
actual grab volume. For purposes of establishing the sampling shall be tailored for the application. Container components
frequency for a batch, only the actual volume should be used. including gaskets and O-rings, couplings, closures, seals, and
relief valves should be assessed when reviewing the compat-
11.4 The actual grab volume may be determined as an
ibility of container materials. The materials used in the
average by measuring 100 grabs into a suitably sized graduated
construction of the sample container shall be compatible with
cylinder. The volume contained in the cylinder at the end of test
the fluids to be collected and retained, as well as not compro-
shall be divided by 100 (or the number of grabs taken) to
mising the properties of interest to be tested. Some contami-
establish the actual grab volume.
nants may be adsorbed or absorbed by typical container
11.4.1 For example, if a sampler grabs 100 samples with the
materials. Special coatings or surface preparations may be
nominal grab size of 1.0 mL and an actual grab size of 1.2 mL,
required to avoid such effects.
the end result would be 120 mL. In that situation, the person
12.1.5 The design of the sample container shall facilitate
taking the sample could expect to observe anywhere from a
mixing of the sample to obtain a representative sample. The
low of 114 mL to a high of 126 mL during future verifications
sample container may require special construction details to
of the grab size.
obtain an aliquot or test specimen for the purpose of perform-
12. Containers
ing an analysis and sample retention. Some analyses require
that the sample not be exposed to air which will impact the
12.1 Sample Containers:
method of sealing the container as well as other design
12.1.1 A sample container is required to hold and maintain
considerations.
the composition of the sample in liquid form. This includes
both stationary and portable containers, either of which may be
NOTE 5—If an aliquot or test specimen is to be drawn directly into the
of variable or fixed volume design. If the loss of vapors will
testing device, the primary sample container may need to have the
significantly affect the analysis of the sample, a variable
capability of being homogenized.
volume type container should be considered. Materials of
12.1.6 Sample containers that are exposed to ambient envi-
construction should be compatible with the petroleum or
ronmental conditions (that is, sunlight, rain, heat, cold, ice, and
petroleum product sampled. In general, one sample container
other weather conditions) may impact the ability to mix and
should be used for each batch. Sampling a single batch into two
remove aliquots (for example, viscous or waxy products at
containers should be avoided since this will increase the
low-temperature extremes) or sample integrity (for example,
potential for error.
high-temperature loss of light ends of high RVP products).
12.1.2 Fixed primary sample containers require local mix-
12.1.7 A sampling system will typically be comprised of
ing. Perform flushing, cleaning, and inspection of the internal
one or more sample containers (see Fig. 8). Multiple containers
mixing system after each batch. Clean, flush, and inspect
may be required on systems moving multiple batches, to take
transportable primary containers either on location or at the
samples of linefill, or even to provide a safety backup.
laboratory.
Consider the number of containers to be used, how these will
12.1.3 The containers types will generally be either variable
be monitored, and whether the sample trapped in the intercon-
volume (constant pressure) or fixed volume (constant volume).
necting tubing will influence the representivity of the sample.
Sample containers may be stationary or portable and shall
Use methods to provide purging from the extraction point to
allow for cleaning and inspection. When designed for off-site
the container. Failure to purge into another empty container or
analysis, both in-line and slip stream sample loop-type sam-
drain system will compromise the integrity of the next sample.
pling systems will have primary sample containers. Use a
The purge volumes are variable and in a multi-product system,
sample container designed to hold and maintain the composi-
purge volumes required are often a multiplier of the actual
tion of the sample in liquid form. Stationary systems typically
volume to sweep clingage away. Consult with manufacturer for
require local product mixing for any potentially nonhomoge-
guidance with system purging requirements.
neous product. Stationary sample containers remain pe
...