Welding Process - WIKA TC59-W Betriebsanleitung

6. Commissioning, operation
6.4 Tests/Checks
Test loop resistance of the thermocouple circuit at ambient temperature prior to welding/
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routing the WELD-PAD, record results.
After completing the welding/routing of the WELD-PAD to the tube, test loop resistance
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at ambient temperature and compare.
EN
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If a deviation of greater than 5 % between readings occurs, please contact WIKA.
Perform any non-destructive examination or heat treatment as required.
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Ensure adequate tube wall thickness at the weld locations. This can be checked by
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thickness testing to customer specifications.

6.5 Welding process

Gas Tungsten Arc Welding (GTAW) is the suggested welding process due to its relatively
clean weld. During welding operation, the requirements of the relevant material data
sheets and the applicable directives and standards must be considered regarding the
heat treatment, filler rods or welding procedures. Proper installation is a major step in the
success of a WELD-PAD installation. Although the WELD-PAD is one of the most rugged
sensors available, it can be destroyed by improper welding.
6.6 WELD-PAD welding
Locate the thermocouple at the appropriate location on the tube.
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Weld the thermocouple pad to the tube.
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Use 3.2 mm (1/8") fillet weld to weld 3 sides using one continuous pass (see figure 1).
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WARNING!
Do not weld the end where the sheath leaves the WELD-PAD.
WARNING!
Ensure the thermocouple tip is in contact with the furnace tube.
Figure 1: Welding details
Fillet
weld
12 WIKA operating instructions model TC59-W (WELD-PAD)