Estudo de caso: reparo de tubulão de caldeira aquatubular por processo de soldagem

Abstract

This work aims to present a technical analysis of a modification and repair project carried out on a steam drum of a CBC-VU60 boiler, focusing on the welding processes employed and the non-destructive tests applied before and after the repairs. The research was motivated by the identification of through-thickness cracks in critical areas of the component, compromising the structural integrity required for the safe and efficient operation of the steam boiler. Subsequently, non-destructive testing using liquid penetrant was performed in the regions indicated by the acoustic emission test, with the objective of identifying possible cracks in the equipment. The results of this test indicated the presence of two areas of acoustic activity, delimiting the regions of interest, since it is a qualitative test. Another qualitative liquid penetrant test was then carried out in the regions indicated by the acoustic emission test, again aiming to identify possible cracks in the equipment. The repair stage involved mechanical grinding of the cracks, controlled preheating of the affected regions, and welding using the SMAW process with E7018-H4 electrodes. To validate the repairs, new liquid penetrant tests, visual inspection, and Phased Array ultrasonic testing were applied. All processes were documented in a technical report and included in the equipment’s records. It is concluded that the procedures adopted met the requirements of ASME Sections I and VIII, as well as Regulatory Standard No. 13, ensuring the reliability of the repairs and extending the operational service life of the steam drum. This study reinforces the importance of integrating inspection techniques and welding practices in the maintenance of critical components of steam boilers.