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Layered Defense: Prevention and Mitigation in Asset Integrity and Process Safety


Layered Defense: Prevention and Mitigation in Asset Integrity and Process Safety






In the high-stakes worlds of Asset Integrity Management (AIM) and Process Safety Management (PSM), our goal is to operate safely and reliably. 




A key strategy in achieving this is the implementation of a layered defense, built upon the principles of Prevention and Mitigation.


Through Implementing principles of PSM, we aim to build layers of protection to stop incidents before they happen (Prevention) and to minimize the impact if they do (Mitigation).




Prevention: Stopping Incidents at the Source

In AIM and PSM, prevention is about being proactive. It involves:


  • Robust Design and Engineering: Selecting appropriate materials, designing for intended operating conditions, and ensuring sound engineering practices from the outset. This is the "Inherent Safe Plant Design" layer.

  • Strict Operating Procedures: Implementing and adhering to clear and safe work procedures ("Operations Procedures" in the Bowtie).

  • Regular Inspection and Maintenance: Proactively identifying and addressing potential degradation or failure mechanisms through scheduled inspections (like the Current Transformer (CT) testing we saw in the MV switchgear document [cite: 1]) and preventive maintenance programs. This falls under "Maintenance and Inspection."

  • Control and Alarm Systems: Utilizing control systems and alarms ("Control, Alarm & Shutdown System" and "Alarm & operator intervention") to maintain stable operations and alert personnel to deviations.

  • Safety Instrumented Systems (SIS): Implementing automated safety systems like Emergency Shutdown (ESD) to prevent hazardous situations from escalating ("Safety instrumented system").

  • Management of Change (MOC): Rigorously reviewing and controlling any changes to processes or equipment to prevent unintended safety consequences ("Management of Change").

  • Training and Competency: Ensuring that personnel have the necessary knowledge and skills to perform their tasks safely and effectively ("Training & Competency").



Mitigation: Limiting the Consequences


Despite our best preventative efforts, sometimes things can still go wrong. That's where mitigation comes in, aiming to reduce the impact of an incident:


  • Emergency Response Planning: Having well-defined and practiced plans to respond effectively to incidents ("Plant emergency response layer").

  • Physical Barriers: Implementing measures like dikes to contain spills ("Dike").

  • Pressure Relief and Fire & Gas Systems: Utilizing relief valves, rupture disks, and fire and gas detection/suppression systems to control and respond to specific hazards ("Relief valve, rupture disk, F&G system").



The Importance of Both


A truly effective safety strategy doesn't rely solely on prevention or mitigation. It requires a balanced approach where strong preventative measures reduce the likelihood of an incident, and robust mitigation measures minimize the potential consequences if one does occur.


As the text highlighted, this is a shared responsibility, guided by thorough risk assessment. By understanding the potential hazards and their risks, we can strategically implement layers of both prevention and mitigation to create a safer operating environment in asset-intensive and potentially hazardous industries.





What are your thoughts on the balance between prevention and mitigation in AIM and PSM? Share your insights below.

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