ASTM D8468-23

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: D8468 − 23
Standard Practice for
Data Recording Procedure for Welding Devices Used to
1
Produce Thermal Fusion Welds in Geomembrane Systems
This standard is issued under the fixed designation D8468; 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 3. Summary of Practice
1.1 This practice establishes the minimum required data 3.1 This practice specifies data acquisition capabilities for
recording, saving, and reporting requirements for data acqui- the purpose of recording the welding parameters used in any
sition devices used in thermal fusion welding of geomembrane location along the entire length of a weld. The recording of the
systems. Thermal fusion welding devices may include hot- welding parameters allows for real-time monitoring as well as
wedge or hot-air wedge welders. From the data collected using post-production seam analysis comparison to the trial welds
this practice, it is possible to compare the welding parameters carried out.
used on any production weld to those obtained during the trial
3.2 The data recorded can be used for construction quality
welding and to the set welding parameters. This practice does
control, construction quality assurance, and other metrics.
not purport to identify the quality of any given weld. This
standard can be used for all geomembranes, homogeneous or
4. Significance and Use
scrimreinforced, that can be seamed by thermal fusion welding
4.1 Standard wedge welding devices rely on the operator to
methods.
properly adjust the welding parameters (temperature, speed,
1.2 This standard does not purport to address all of the
and pressure) which are needed to create a sound weld.
safety concerns, if any, associated with its use. It is the
Changes in one or more of these parameters during production
responsibility of the user of this standard to establish appro-
seaming, whether deliberate or accidental, can lead to poor
priate safety, health, and environmental practices and deter-
weld quality. Prior to data acquisition systems, verifying
mine the applicability of regulatory limitations prior to use.
welding parameters throughout the welding process relied
1.3 This international standard was developed in accor-
solely on periodic visual observations and documentation,
dance with internationally recognized principles on standard-
leaving substantial room for error. This ASTM standard
ization established in the Decision on Principles for the
practice, which requires a data acquisition system to be
Development of International Standards, Guides and Recom-
installed on thermal fusion welding devices, allows for the
mendations issued by the World Trade Organization Technical
recording of these welding parameters along the entire length
Barriers to Trade (TBT) Committee.
of the welded seam at pre-determined intervals, throughout the
entire thermal fusion seaming process.
2. Terminology
4.2 The acquired data can be used in the construction
2.1 Definitions:
quality control / construction quality assurance program to
2.1.1 construction quality assurance (CQA)—a planned sys-
compare the welding parameters at recorded locations along
tem of activities that provides the owner and permitting agency
the welded length to preset values, such as the values obtained
assurance that the facility was constructed as specified in the
during the trial seam, to facilitate detection of anomalies
design.
anywhere on the welded length.
2.1.2 construction quality control (CQC)—a planned system
4.3 This practice does not cover the precision of the
of inspections that is used to directly monitor and ensure that
measurement, that is, the accuracy of the recorded values of
a minimum standard of materials and workmanship is used to
temperature, speed, pressure, or position on the site. It is
ensure the performance of the facility according to the design.
limited to the data acquisition process.
2.1.3 data recording device (“device”)—an instrument that
4.4 Data acquisition parameters, such as the frequency at
obtains and stores information.
which the data are recorded, may be adjusted by the user
depending on project specifications.
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This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-
thetics and is the direct responsibility of Subcommittee D35.10 on Geomembranes.
5. Apparatus—General Requirements
Current edition approved Jan. 1, 2023. Published January 2023. DOI: 10.1520/
D8468-23. 5.1 Data Recording Devi
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