ASTM D8468-23

4.1?Standard wedge welding devices rely on the operator to properly adjust the welding parameters (temperature, speed, and pressure) which are needed to create a sound weld. Changes in one or more of these parameters during production seaming, whether deliberate or accidental, can lead to poor weld quality. Prior to data acquisition systems, verifying welding parameters throughout the welding process relied solely on periodic visual observations and documentation, leaving substantial room for error. This ASTM standard practice, which requires a data acquisition system to be installed on thermal fusion welding devices, allows for the recording of these welding parameters along the entire length of the welded seam at pre-determined intervals, throughout the entire thermal fusion seaming process.

4.2?The acquired data can be used in the construction quality control / construction quality assurance program to compare the welding parameters at recorded locations along the welded length to preset values, such as the values obtained during the trial seam, to facilitate detection of anomalies anywhere on the welded length.

4.3?This practice does not cover the precision of the measurement, that is, the accuracy of the recorded values of temperature, speed, pressure, or position on the site. It is limited to the data acquisition process.

4.4?Data acquisition parameters, such as the frequency at which the data are recorded, may be adjusted by the user depending on project specifications.

1.1?This practice establishes the minimum required data recording, saving, and reporting requirements for data acquisition devices used in thermal fusion welding of geomembrane systems. Thermal fusion welding devices may include hot-wedge or hot-air wedge welders. From the data collected using this practice, it is possible to compare the welding parameters used on any production weld to those obtained during the trial welding and to the set welding parameters. This practice does not purport to identify the quality of any given weld. This standard can be used for all geomembranes, homogeneous or scrim reinforced, that can be seamed by thermal fusion welding methods.

1.2?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.

1.3?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.