Corrosion Case Study of SS316L Amine/Amine Plate Heat Exchanger at SPGC Ethane Refining Unit

摘要

Ethane treatment process unit at South Pars Gas Complex includes sweetening the gas by acid gas absorption with Di-Ethanol Amine (DEA). In this process hot lean amine discharging from regeneration tower, pre-heats the rich amine by a plate heat exchanger (PHE). The operation, in SPGC recorded a noticeable decrease in PHE performance and recommended to isolate for inspection. Primary visual inspections revealed significant scaling in rich amine side. Consequently, chemical composition of scales was analysed which iron oxide detected as predominant compound. Also penetration test (PT) revealed pitting corrosion on gasket seat. Pitting morphology and mechanism investigated using Stereo Microscope (SM), Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). In addition gasket glue was analysed using FTIR spectroscopy to find halide compounds. Results show that the chlorine extracted from PVC compound of gasket glue and caused pitting initiation. Besides, residual stresses from cold work during plate forming activated the Chloride Stress Corrosion Cracking (CLSCC) mechanism which initiated from bottom of pits and then cracks propagated through grain boundary.