Metallurgical Failure Analysis: A Case Study of Observing a Leak in a Stainless Steel SS304 Pipe

Abstract

In this study, metallurgical failure analysis of leak observed in SS304 pipe of 355.6 mm out side diameter and 4.78 mm wall thickness is invistigated. The pipe was hydrostatic pressure tested, and the leakage was observed on the pipe after priod of time. Visual test, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), and energy dispersive X-ray spectroscopy (EDS) were carried out on the samples. Heat tint and griding marks were observed during visual inspection. In addition, scanning electron microscopy reveales many pinholes, tunnel-types in the leaked area. Energy-dispersive X-ray spectroscopy also shows that a multifactorial corrosion process due to stagnant water conditions, bacterial activity, corrosive elements contribte to the leak in the pipe. The results show that the leak damage essentially due to stagnancy of water—improper dry-out of the pipe after hydro test leading to chloride pitting attack and eventually causing leakage. The decomposition of the passive oxide layer due to the high concentration of chlorine and accumulation of microbial byproducts played an important role in examining the SS304 pipe. Preventive measures such as proper inspection, proper welding practices, sanitation, disinfection, and water management are important for corrosion prevention.