Overview
ISO 13916:2025 - Welding - Measurement of preheating temperature, interpass temperature and preheat maintenance temperature (3rd edition) specifies how to measure and record temperatures used to control fusion welding operations. The standard covers measurement points, timing, equipment options and minimum record content for preheating temperature, interpass temperature and preheat maintenance temperature. It applies primarily to fusion welding and can be used, as appropriate, for other welding processes. It does not cover post‑weld heat treatment temperature measurement.
Key topics and requirements
- Measurement points
- For piece thickness t ≤ 50 mm: measure on the surface facing the welder. If the heat source is centered on the joint, measure at A = 4 × t (maximum 50 mm) from the joint edge.
- If the heat source is outside the joint (e.g., fixed heaters), measure on the weld metal or immediately adjacent base metal surface.
- For t > 50 mm: required temperature must be met in base metal at ≥75 mm from the joint (or by agreement) in all directions.
- Timing of measurements
- Interpass temperature: measure in the weld zone just before the next pass.
- Preheat maintenance temperature: monitor during welding interruptions when specified.
- Equipment and methods
- Acceptable measurement materials include thermosensitive products (crayons/paints - TS), contact thermometers (CT), thermocouples (TE) and non‑contact optical/electrical devices (TB).
- ISO 17662 is referenced for calibration, verification and validation of temperature measurement equipment.
- Equilibration guidance
- When measuring on the heated side only, confirm temperature after allowing thermal equilibrium (approx. 2 minutes per 25 mm of base metal thickness) before recording.
- Records and designation
- When records are required, include measured preheat, interpass and preheat maintenance temperatures in °C and note any deviations.
- Standard gives designation examples for records (e.g., “Temperature ISO 13916:2025 T 155 - CT”).
Applications and users
Who uses ISO 13916:2025:
- Welding engineers and procedure writers preparing welding procedure specifications (WPS)
- Quality assurance and inspection personnel in fabrication and construction
- Welding contractors, fabricators, and inspectors ensuring process control
Practical uses include consistent welding temperature measurement, standardizing preheat/interpass control across projects, and documenting temperature records for compliance and traceability.
Related standards
- ISO 17662 - Calibration, verification and validation of welding temperature measurement equipment (referenced for equipment competence and calibration).
Keywords: ISO 13916, welding preheat, interpass temperature measurement, preheat maintenance, welding temperature measurement, thermocouple, contact thermometer, thermosensitive crayons.
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