Investigation of hydrogen embrittlement failure in a steam separator by field metallography

In this work the failure by cracking of a steam separator vessel constructed from ASTM A-516 Gr.60 steel was investigated by field metallography. The application of this non-destructive method allowed the determination of failure mechanism, which was useful to give recommendations for repair by welding and prevent future failures. The cracks identifications were made by penetrant liquid and after this; the field metallography test was performed in the diverse regions with cracks. Finally, the replicas were analyzed in laboratory by optical microscopy. The failure was caused by hydrogen embrittlement process principally in the heat affected zone (HAZ) because of the high reinforcement welding joint, residual stresses values and elevated concentrations of compounds controlling the parameters of the boiler feed water.