Failure analysis of admiralty brass tubes in a surface condenser: a case study at the petrochemical industry

摘要

The surface condenser in the steam turbine plays an essential role during the condensation process. Failure of surface condenser tubes is a critical factor for its efficiency and lifetime. This paper presents the failure of a surface condenser's admiralty brass tubes from a petrochemical plant in Indonesia after four years out of twenty years of expected lifetime. Eddy Current inspection results show some of the leaks were in the condensing zone. The characteristics of ammonia corrosion were found after visual and SEM examinations. Examination using stereo and metallurgical microscopes showed that the tubes' external surface experienced corrosion, grooving attack, and significant wall thinning. SEM observation at the edge of the baffle revealed the preferential attack at the alloy's grain boundaries. Water quality analysis indicated high ammonia concentration because the excess amount of Elimin-Ox oxygen scavenger in the water can produce ammonia that corroded the tubes, leading to leakage and failure.