Session: MF-20-02 Material Quality and Failure Analysis-2

Paper Number: 152260

152260 - Failure Analysis of the Cracked Synthetic Gas Pipe 

Abstract: 

A synthetic gas pipe in a certain chemical plant were found to leak after one years of normal operation. The pipe was made of 20G material, with CO and H₂ synthetic gas as the medium, and the insulation layer material was aluminum silicate fiber pipe shell. The operating temperature for synthetic gas pipe is 135℃.There were obvious grooves and corrosion marks at the near location of the cracked synthetic gas pipe.

By means of macroscopic inspection, chemical composition analysis, metallographic examination, crack morphology analysis, fracture microstructure analysis, and energy spectrum analysis, the failure analysis of the cracked synthetic gas pipe was carried out to determine the cause of the cracking of the synthetic gas pipe, so as to avoid similar leakage accidents. The analysis results indicate that the cracking of the synthetic gas pipe was attributed to caustic stress corrosion crack, and the crack starts from the outer wall of the pipe and gradually extends to the inner wall. The reason for the cracking was that the caustic solution in the external environment infiltrated the insulation layer, which accumulated and concentrated in the grooves on the surface of the synthetic gas pipe, resulting in caustic stress corrosion crack and ultimately leading to the synthetic gas pipe leakage.

Presenting Author: Jun Si Shanghai Institute of Special Equipment Inspection and Technical Research (SSEI)

Presenting Author Biography: Jun Si, senior engineer, has worked in inspection of special equipment for about sixteen years at SSEI. He received his Ph.D degree from ECUST in March 2009. He was qualified as senior inspector and risk-based inspection(RBI) analyst. He has been engaged in related research on Fitness-for-Service(FFS). His current activities include leading structural integrity projects for FFS assessment for mechanical equipment.
His research interests are in structure integrity assessment, failure analysis, simulation technique of material aging, NDT etc.

Authors:

Jun Si Shanghai Institute of Special Equipment Inspection and Technical Research (SSEI)
Xiaolong Xue Shanghai Institute of Special Equipment Inspection and Technical Research (SSEI)
Kun Li Shanghai Institute of Special Equipment Inspection and Technical Research (SSEI)