Controlling the temperature during Post-Weld Heat Treatment (PWHT) is crucial to ensure uniform heating, stress relief, and metallurgical stability of the welded component. This process involves using thermocouples for temperature measurement and a temperature controller to regulate heating. Here's a step-by-step guide on how to do it effectively:
1-Install Thermocouples
Use Type K or N thermocouples for high temperatures.
Attach at least two thermocouples: one near the weld joint and one at the edge for temperature uniformity.
2-Connect to Temperature Controller
Connect the thermocouples to the PID temperature controller for precise control.
Set the target temperature, heat-up rate, holding time, and cooling rate.
3-Control Heating Pads
The controller adjusts power to the heating pads using a solid-state relay (SSR).
Monitor the temperature regularly to ensure even heating.
4-Safe Cooling
Gradually cool the workpiece at 50-100°C per hour to avoid thermal shock.
Ensure the temperature drops below 200°C before removing the heating pads.
With this setup, you can maintain precise and uniform heating during the PWHT process.
