Corrosion failure of superheat steam pipes of an ammonia production plant

The aim of the present work is to determine root causes and mechanisms of corrosion in steam pipes of an ammonia plant. In this order, the morphology of deposits as well as elemental and phase composition of corrosion products were studied by use of different characterization and analyzing techniques such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). In addition, ion chromatography is employed for detection and measuring the concentrations of the ionic species in the steam drum water. Based on the results, acid phosphate corrosion was recognized as the main mechanism for corrosion of the internal areas of steam lines due to improper implementation of phosphate treatment program.