Assessment of premature degradation of a gas injection pipeline due to hydrogen released by the benzene hydrofining equipment

The present research aimed to identify the causes that led to the deterioration of a pipeline comprised in the benzene hydrofining equipment of a refinery. The pipeline ascending branch was perforated, therefore the installation was stopped in order to remove it and replace it. To find the causes of the premature degradation the following investigations were performed: macroscopic examination of the pipe elbow, chemical composition, microstructure and hardness, analysis of the porosity zone from the welded joint, analysis of corrosion products deposit samples taken from inside the pipe by X-ray fluorescence and X-ray diffractometry, assessment of the different corrosion processes affecting the pipeline.