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PWHT / Preheat

Post Weld Heat Treatment Services ( PWHT ) is defined as one of heat treatments done after welding/machining to improve the Chemical mechanical properties of weldment / machined surfaces. In concept, PWHT covers many different potential treatments. However, in steel fabrication, most common procedure used is Stress Relieving.

Post-Weld Heat Treatment/PWHT purpose

The primary reasons that components are required to be subjected to PWHT within the ASME Code rules are that PWHT reduces residual stresses and tempers hardened microstructures. PWHT will achieve both of these results but might not positively benefit the overall properties of the weldment if not properly controlled, particularly in terms of the toughness in the heat-affected zone. When toughness is a requirement, the Codes will impose additional controls on the PWHT, such as time at temperature controls. PWHT done to meet the Code requirements is typically performed at subcritical temperatures.

IEQS has a talented crew that uses diesel fuel as source of heating for stress relieving for pressure vessels with the sole objective of reinforcing process and component integrity and quality. The experience heat treaters from IEQS have the experience, equipment, and expertise to develop custom configuration for your particular process. Our heating processes include low-Range, Mid-Range & High-Range Temperature Heating.