According to ISO 13916:2017, interpass temperature is a critical parameter in welding that directly influences the heat-affected zone (HAZ) microstructure and mechanical properties. Exceeding the recommended interpass temperature can lead to grain coarsening, reduced toughness, and increased susceptibility to hydrogen-induced cracking.
Most fabrication shops still rely on manual temperature measurement using contact thermometers or infrared pyrometers. However, the timing and location of measurement are often inconsistent. ISO 13916 specifies that the interpass temperature should be measured at a defined distance from the weld toe, typically 25 mm, and recorded before each subsequent pass.
Key considerations for effective interpass temperature control:
• Always measure at the same location relative to the weld toe.
• Allow sufficient time for temperature stabilization before measurement.
• Document interpass temperature readings on the weld log for traceability.
• For low-alloy steels, maintain the interpass temperature below the preheat temperature to avoid HAZ softening.
• Use calibrated equipment and verify measurement technique during welder qualification.
Auditors typically check interpass temperature records against the WPS. Missing or inconsistent readings are a common non-conformance. A simple digital log in Excel can help track trends and flag deviations in real time.
How do you ensure interpass temperature compliance on your site?
Source: ISO 13916, 2017