ASTM D5503-94(2003)
(Practice)Standard Practice for Natural Gas Sample-Handling and Conditioning Systems for Pipeline Instrumentation
Standard Practice for Natural Gas Sample-Handling and Conditioning Systems for Pipeline Instrumentation
SIGNIFICANCE AND USE
A well-designed sample-handling and conditioning system is essential to the accuracy and reliability of pipeline instruments. Approximately 70 % of the problems encountered are associated with the sampling system.
SCOPE
1.1 This practice covers sample-handling and conditioning systems for typical pipeline monitoring instrumentation (gas chromatographs, moisture analyzers, and so forth). The selection of the sample-handling and conditioning system depends upon the operating conditions and stream composition.
1.2 This practice is intended for single-phase mixtures that vary in composition. A representative sample cannot be obtained from a two-phase stream.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 The values stated in SI units are to be regarded as standard. The values stated in English units are for information only.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D5503–94 (Reapproved 2003)
Standard Practice for
Natural Gas Sample-Handling and Conditioning Systems for
Pipeline Instrumentation
This standard is issued under the fixed designation D 5503; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This practice covers sample-handling and conditioning 3.1 Definitions:
systems for typical pipeline monitoring instrumentation (gas 3.1.1 compressed natural gas—natural gas compressed to
chromatographs, moisture analyzers, and so forth). The selec- approximately 3600 psi.
tion of the sample-handling and conditioning system depends 3.1.2 density—mass per unit volume of the substance being
upon the operating conditions and stream composition. considered.
1.2 This practice is intended for single-phase mixtures that 3.1.3 dew point—the temperature and pressure at which the
vary in composition. A representative sample cannot be ob- first droplet of liquid forms from a vapor.
tained from a two-phase stream. 3.1.4 lag time—time required to transport the sample to the
1.3 This standard does not purport to address all of the analyzer.
safety concerns, if any, associated with its use. It is the 3.1.5 natural gas—mixture of low molecular weight hydro-
responsibility of the user of this standard to establish appro- carbons obtained from petroleum-bearing regions.
priate safety and health practices and determine the applica- 3.1.6 sample probe—device to extract a representative
bility of regulatory limitations prior to use. sample from the pipeline.
1.4 The values stated in SI units are to be regarded as 3.1.7 system turnaround time—the time required to trans-
standard.The values stated in English units are for information port the sample to the analyzer and to measure the desired
only. components.
2. Referenced Documents 4. Significance and Use
2.1 ASTM Standards: 4.1 Awell-designed sample-handling and conditioning sys-
D 1142 Test Method for Water Vapor Content of Gaseous tem is essential to the accuracy and reliability of pipeline
Fuels by Measurement of Dew-Point Temperature instruments.Approximately 70 % of the problems encountered
D 3764 Practice for Validation of Process Stream Analyz- are associated with the sampling system.
ers
5. Selection of Sample-Handling and Conditioning
2.2 Other Documents:
4 System
ANSI/API 2530 (AGA Report Number 3)
5.1 The sample-handling and conditioning system must
AGA Report Number 8
NACE Standard MR-01-75 extract a representative sample from a flowing pipeline, trans-
port the sample to the analyzer, condition the sample to be
compatible with the analyzer, switch sample streams and
This practice is under the jurisdiction of ASTM Committee D03 on Gaseous
calibration gases, transport excess sample to recovery (or
Fuels and is the direct responsibility of Subcommittee D03.01 on Collection and
disposal), and resist corrosion by the sample.
Measurement of Gaseous Samples.
Current edition approved May 10, 2003. Published August 2003. Originally 5.2 The sample probe should be located in a flowing
approved in 1994. Last previous edition approved in 1994 as D 5503 – 94.
pipeline where the flow is fully developed (little turbulence)
Annual Book of ASTM Standards, Vol 05.06.
and where the composition is representative. In areas of high
Annual Book of ASTM Standards, Vol 05.02.
turbulence, the contaminates that normally flow along the
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036.
bottom or the wall of the pipeline will form aerosols.
Available from American Gas Association, 1515 Wilson Blvd., Arlington, VA
5.3 The purpose of the sample probe is to extract a repre-
22209.
6 sentative sample by obtaining it near the center of the pipeline
Available from National Association of Corrosion Engineers, 1440-T S. Creek
Dr., Houston, TX 77084. where changes in stream composition can be quickly detected.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5503–94 (2003)
5.3.1 Thetipinthesampleprobeshouldbepositionedinthe
center one third of the pipeline, away from the pipeline wall
where large particles accumulate.
5.3.2 Theprobeshouldbeaminimumoffivepipediameters
from any device that could produce aerosols or significant
pressure drop.
5.3.3 The sample probe should not be located within a
defined meter tube region (see ANSI/API 2530 AGA Report
Number 3 and AGA Report Number 8 for more information).
5.3.4 The sample probe should be mounted vertically from
thetoponhorizontalpipelines.Thesampleprobeshouldnotbe
located on vertical pipelines.
5.4 The sampling-handling system must transport the
sample to the analyzer and dispose of excess sample. Since the
sampling point and the analyzer may be separated by some
distance, the time required to transport the sample to the
analyzer can contribute significantly to the system turnaround
FIG. 1 Cross Section of Common In-Line Filters
time.
5.4.1 The analyzer should be located as close to the sam-
6. Apparatus
pling point as is practical to minimize the sample lag time.
6.1 The following are common components of a sample-
5.4.2 The sample-handling system should be equipped with
handling and conditioning system (see Refs (1) and (2) for
a full open ball valve and a particular filter.
more information).
5.5 The sizing of the sample transport line will be influ-
6.1.1 Ball valves, needle valves, and solenoid valves are
enced by a number of factors:
typically used for stream switching, sample shutoff, calibration
5.5.1 The sample point pressure and the location of the
gas introduction, or sample vent and bypass systems.
pressure reduction regulator.
6.1.2 Most pipeline samples require some filtering. Since all
filter elements eventually plug, they should be replaced on a
5.5.2 The acceptable lag time between the sample point and
regular maintenance schedule. There are several types of filter
the analyzer.
designs.
5.5.3 The requirements of the analyzer, such as flow rate,
6.1.2.1 In-Line Filter—All of the sample passes through an
pressure, and temperature for the analysis. For multistream
in-line filter. The active filter elements are available in Teflon
systems,thesamplelineandassociatedmanifoldtubingshould
polypropylene, copolymer, or stainless steel. (See Fig. 1.)
be flushed with sufficient sample to assure a representative
6.1.2.2 Bypass Filter—Only a small portion of the sample
sample of the selected stream.
passes through a bypass filter, while a majority of the sample
5.5.4 The presence of sample-conditioning elements will
passes across its surface keeping it clean. The active filter
contribute to the lag time and must be considered in the
element is either a disposable cartridge or a reusable sintered
calculation of the minimum sample flow rate.
metal element. (See Fig. 2.)
5.5.4.1 Each element could be considered as an equivalent
6.1.2.3 Cyclone Filter—The cyclone filter is a centrifugal
length of sample line and added to the length of line from the
cleanup device.The sample enters at high velocity tangentially
sample point to the analyzer.
to the wall of a cylindrical-shaped vessel with a conical-shaped
5.5.4.2 The purge time of each element is calculated as the bottom.The centrifugal force developed by the spinning action
of the gas as it follows the shape of the vessel forces particles
time necessary for five volumes of sample to flow through the
element. and droplets to the wall where they are removed through the
vent flow. (See Fig. 3.)
5.5.5 A vapor sample must be kept at least 10°C above the
6.1.2.4 Coalescing Filter—Coalescers,alsoknownasmem-
hydrocarbon dew point temperature to prevent condensation of
brane separators, are used to force finely divided liquid
thesample.Thesamplelineshouldbeheattracedandinsulated
droplets to combine into larger droplets so they can be
when appropriate.
separated by gravity. The design of the coalescer body forces
5.5.5.1 For compressed natural gas (CNG), the pressure
the heavier phase out the bottom and the lighter phase out the
must be reduced in two stages to avoid condensation of liquids
top. The flow rates out the top and the bottom are critical for
caused by the Joule-Thompson effect. In a heated zone at
proper operation. (See Fig. 4.)
approximately 50°C, the pressure should be dropped to ap-
(1) Since this process removes part of the sample, the
proximately10MPa(1500psig)andthentoasuitablepressure
impact on sample composition must be considered.
for the analyzer. Any conditioning of the sample must be
completed in the heated zone.
5.5.5.2 Thesamplelinefromtheheatedzonetotheanalyzer 7
The boldface numbers in parenthese
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