Root Cause Failure Analysis and Remaining Life Assessment of CO Reformer Tubes
ETD carried out Root Cause Failure Analysis and Remaining Life Assessment of CO Reformer Tubes for a Petrochemical Plant. It is reported that the failures occured at catalyst tubes and flexi tubes of the CO reformer section.
The scope of work carried out included:
- Visual examination of all tube samples including internal deposit and external appearance;
- Assessment of condition of the tubes inner & outer surfaces and bulged areas;
- Dimensional examination of the tube samples to examine diameter growth;
- Chemical analysis of base material to determine the chemical composition of the tube material to establish actual material constituents;
- Metallographic examination of the tube samples using optical microscopy to assess the condition of internal and external surfaces and also to identify the damage mechanism(s) (i.e. creep, carburization, localized heating or others);
- Metallographic examination of two tube samples (two worse tubes will be selected based on visual examination) using SEM (Scanning Electron Microscope) to confirm the damage mechanism(s);
- Mechanical testing (Hardness & Tensile testing) and evaluation to determine the equivalent tensile strength values (using published hardness/UTS correlation tables) to assess the mechanical strength or softening of the tube materials or welds;
- Basic review of design drawings, operating parameters, previous failure and maintenance history.
- Root Cause Failure Analysis (RCA) based on the findings of above investigations.
- Measurements of the thickness of tube internal oxide/scale to determine the actual operating temperature;
- Assessment of tube remaining life based on the estimation of actual tube operating temperature and the data from published literature;
- A report covering results of investigations, RCA & RLA analysis and recommendations for any further actions to be taken for safe operation of the components.
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