Two temperatures can describe different points in the joining sequence.
Identify the observation stage
TWI defines preheat before welding begins and interpass temperature for subsequent runs. An interpass requirement can include a different lower or upper condition in the actual procedure. Primary reference: TWI technical explanation.
The stage identity belongs beside each observation. A temperature taken before the first run cannot simply be relabeled as evidence of the condition before a later run. Preserve the relevant location and timing as well.
Read an invented sequence
Imagine a fictional record reports 90°C before the first run. After that run and its waiting interval, it reports 150°C before the next run. Those observations occupy different stages even though both describe the same assembly.
They do not prove compliance with an unspecified procedure, and neither is a recommended temperature. A sheet retaining only one field called weld temperature would lose the sequence and make a later comparison difficult to interpret.
Build the stage record
Create rows for run identity, observation time, location, stated temperature and the procedure condition being reviewed. Record the relevant minimum or maximum only from the actual authorized requirement.
Ask which observation supports each required stage rather than using one favorable value for the entire multi-run joint. This gives a reviewer a clear evidence request while keeping the material/process assessment separate from the temperature timeline. The example supplies no holding interval, reheating instruction or fabrication qualification.
Customer Questions
When does the cited preheat description apply?
Before welding begins.
Which invented reading precedes the later run?
The 150°C observation.
Do the values establish procedure compliance?
The actual requirements and observation basis are still needed.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
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