Failure Analyses

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Forensic Engineering are primarily concerned with the correct reconstruction of an incident which resulted in failure, loss, injury or death. As such, Forensic Engineering is also often utilized in investigations with a commercial or industrial focus. Engineering knowledge, concepts and techniques are used in order to arrive at the required reconstruction.

The forensic engineer meticulously investigates accidents and failures with the objective of establishing causation and the sequence of events leading to the accident. This work can also be utilized by the legal profession for both civil and criminal court proceedings.

Grayston Road temporary pedestrian bridge collapse
Grayston Road temporary pedestrian bridge collapse

Reconstructing the sequence of failure events of a reclaimer collapse

Due to the increasing complexity of plants and the high cost of capital equipment, a failure of a critical item of equipment could amount to many millions of Rand in terms of lost production and equipment replacement costs, not to mention the possibility of lost lives.

In order to prevent a failure from re-occurring, it is essential that a thorough understanding of the root cause of the failure be gained. SecMet has conducted countless failure investigations over the years, which range in complexity from a relatively simple fatigue failure of a shaft to explosion of pressurized equipment and collapsed bridges which resulted in fatalities, and as a consequence have developed comprehensive competence in this field.

Failed Shaft
Failed Shaft

 

The typical stages of failure investigations are:

  • A site visit for documenting the site and prevailing conditions before and during the failure.
  • Consultation with stakeholders and recording of testimony of key personnel (where applicable).
  • On-site post-mortem of the damage and identification of key components earmarked for further scrutiny.
  • Recording of the incident area and failed components with relative placement via digital photography and/or geographical measurements (e.g. laser scanning).
  • A detailed analysis and characterisation of the failed component(s) via:
    • Macroscopic examination supplemented by stereo microscopy.
    • Chemical analysis
    • Mechanical testing and material conformance verification. This range from basic hardness testing to comprehensive fracture toughness assessments.
    • Metallographic examination via optical microscopy.
    • Fractography (the characterisation of the fracture surface) using scanning electron microscopy with spectrometry to identify aggressive reagents that may have caused or assisted the failure.
  • Devising of Root Cause Analysis (RCA) charts (e.g. “Cause-and-Effect” or “Fishbone” diagrams).
  • Comprehensive report providing conclusions and recommendations.
  • Follow-up to assess implementation of recommendations and suitable mitigation of the root cause.
fishbone diagram
Example of a fishbone diagram indicating the root cause via the red highlighted aspects for the failure of heat exchanger tube. (Click to enlarge)
SEM image of globe filament that failed in ductile manner
SEM image of globe filament that failed in a ductile manner
Microstructure with stress corrosion cracking
Microstructure with stress corrosion cracking