NBL Engineering Services Pvt. Ltd.

Tremendous amount of heat generated during welding induces two types of stresses (elastic and residual stress) and increases the ductility of the metal. Post heated weldments have significantly less residual stress compared to untreated welds, therefore having better resistance to corrosion & caustic embrittlement. Residual stresses developed through machining affects dimensional stability of the components by continuous micro movements of plastically misfit and unstable atoms. PWHT helps reorient these atoms into a new equilibrium position.

Advantages:

• Controls and documents welding preheat to reduce thermal stress.

• Improves the microstructure and durability of the heat-affected zone.

• Tempers the metal and reduces tensile stresses, minimizing the risk of brittle fracture, stress, corrosion cracking and metal fatigue.

• Ensures the structural integrity of the vessel or unit during treatment