Analysis of the recomposition of thickness with welding of tubes coated with overlay of the furnace of chemical recovery boilers

Abstract

Welding processes are often used in the repair of furnace tubes of chemical recovery boilers during maintenance interventions. However, this method of repair can cause changes in the mechanical and metallurgical properties of the base materials. These changes in the cross section of the tube, in practice, cannot always be verified immediately, due to the lack of specific methodologies, which are reliable and economically viable versus the need for operational return of the component. This work was carried out in order to collect the basic information necessary for the reliability of this repair procedure, and what risks these can bring to the operation of the equipment. For this, thinnings were performed located in tubes with manufacturing overlay and performed later recomposition of the overlay, in order to simulate the repair procedures performed during the equipment maintenance shutdowns. The evaluation was made through the microstructural analysis, the residual thickness and the mechanical property of hardness in the region repaired with weld to recompose the coating, revealing no relevant concern in view of what is currently carried out in the field.