Post Weld Heat Treatment (PWHT)

Intertek offers post weld heat treatment (PWHT) to improve weld microstructure and reduce residual stresses developed during welding.

Intertek specialises in performing PWHT for the steel and metal fabrication industries including the construction of pressure vessels, pressure piping, storage tanks, buildings, bridges, offshore platforms, power plants, oil and gas refineries, and petrochemical plants.

There is often a mandatory requirement for PWHT due to compliance with welding codes and specifications on certain materials including but not limited to carbon steels, stainless/high alloy steels and work hardened steels. There may also be PWHT requirements based on the wall thickness of the parts being welded together.

PWHT reduces or redistributes the residual stress introduced by the welding process with a technique that involves heating, soaking and cooling the weldment/machined surface to controlled temperatures. This improves the properties of the weldment/machined surface. Other benefits of PWHT include:

• Improved ductility of the material
• Improved or reduced hardness
• Reduced risk of brittle fracture
• Relaxed thermal stress
• Tempered metal
• Removal of diffusible hydrogen (to prevent hydrogen induced cracking)
• Improved metallurgical structure

Intertek can perform PWHT at both our own premises and at our customers’ sites. Our onsite facilities include large furnaces where we can place numerous weldments/machined surfaces for PWHT. In addition, we provide a pick-up and delivery service. Intertek can carry out PWHT at our customers’ sites at any offshore and onshore location utilizing our portable equipment. 

Our team of highly skilled and trained PWHT technicians ensures that all weldments/machined surfaces brought in for treatment will meet the specified welding code requirements and be fit for purpose.

By partnering with Intertek for PWHT, you will also benefit from our global services and experience. We can provide the non-destructive inspections that are normally required after PWHT is completed - including hardness testing, magnetic particle inspection and after stress radiography. Our metallurgical laboratories and experienced engineers with metallurgical backgrounds add to the wealth of knowledge and expertise needed to execute any critical PWHT while providing Total Quality Assurance.