Title of article :
Root cause analysis for 316L stainless steel tube leakages
Author/Authors :
Kaewkumsai، نويسنده , , S. and Auampan، نويسنده , , S. and Wongpinkaew، نويسنده , , K. and Viyanit، نويسنده , , E.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2014
Abstract :
Perforation of ASTM A270 TP316L stainless steel tube, used for transportation of ozonated high purity water in a pharmaceutical plant, was discovered after 3 months in actual service. The current investigation was conducted in order to explore the root causes of failure. Various techniques including on-site investigation, emission spectroscopy, ion chromatography, radioscopy, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and intergranular corrosion testing were implemented for failure analysis of the tube components. The results revealed that the perforation of tube was initiated from the outer wall and extended to the inner wall by pitting corrosion. The stagnant state of chloride-containing water was the main reason for inducing such corrosion attack. The weld metal was the most susceptible to corrosion attack leading to perforation of the wall thickness, although initiation sites of pitting corrosion were also observed in the base metal. The dimensions of each pit mouth are very small, but enlarged subsurface cavities were observed. The selective dissolution of material due to galvanic effects between delta-ferrite and the austenite matrix occurred in the weld zone. It is suggested that failure prevention could be achieved by controlling the quality of the insulation system. In addition, careful control of welding conditions must be implemented during fabrication.
Keywords :
Pitting corrosion , Welding defect , Tubing failure , Stainless steel
Journal title :
Engineering Failure Analysis
Journal title :
Engineering Failure Analysis