Day 1 – Foundations of Inherent Safer Design
Morning Session: ISD Philosophy and Principles
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- Historical evolution of ISD (Trevor Kletz, Flixborough accident lessons).
- ISD vs. engineered safeguards: prevention vs. mitigation.
- Four main ISD strategies:
- Substitution – replace hazardous chemicals or processes.
- Minimization – reduce inventory and process volumes.
- Moderation – operate under less hazardous conditions.
- Simplification – design out complexity and failure modes.
Afternoon Session: Regulatory and Standards Context
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- Role of ISD in OSHA 29 CFR 1910.119 and EU Seveso III Directive.
- CCPS Guidelines for Inherently Safer Chemical Processes (4th edition).
- IChemE Inherent Safety Guide: best practice applications.
- Case study analysis: Bhopal disaster and the missed ISD opportunities.
Day 2 – Hazard Identification and ISD Integration
Morning Session: Hazard Identification Tools
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- Hazard Identification Frameworks:
- Hazard Identification (HAZID) workshops – early phase hazard spotting.
- Hazard and Operability Studies (HAZOP) – identifying design deviations.
- “What-if” analysis and Checklists – fast-track assessments.
- Integration of ISD with Hazard Studies:
- Embedding ISD prompts in HAZOP guidewords.
- Linking findings to potential substitution, moderation, or simplification actions.
- Ensuring ISD is considered at Stage-Gate reviews (Concept → FEED → Detail).
- Analytical Tools Supporting ISD:
- Quantitative Risk Assessment (QRA) – identifying high-consequence risks where ISD is most impactful.
- Consequence modeling for toxic dispersion, jet fires, and BLEVEs.
- Computational Fluid Dynamics (CFD) to visualize benefit of ISD design changes.
Afternoon Session: ISD in Practice – Hazard Elimination
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- Substitution Strategies:
- Replacing hazardous materials with safer alternatives:
- Chlorine gas → Sodium hypochlorite
- Anhydrous ammonia → Aqueous ammonia, and
- Benzene solvents → Toluene/less toxic solvents.
- Changing hazardous reaction pathways:
- Phosgene-free polymer synthesis.
- Minimization Approaches:
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- Reducing hazardous inventories:
- Small storage tanks vs. large bulk storage, and
- Continuous processing vs. batch operation.
- Minimizing energy densities:
- Lowering system pressures, and
- Designing for smaller inventories in piping (shorter runs, sectionalizing).
- Workshop Exercise:
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- Hazard study case: Hydrocarbon storage terminal:
- Identify substitution opportunities (e.g., safer refrigerants)
- Define inventory minimization strategies (tank sizing, inventory management), and
- Prioritize ISD interventions over engineered add-ons.
Day 3 – ISD in Process and Equipment Design
Morning Session: Process-Level ISD Strategies
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- Reaction Chemistry and Process Routes:
- Selecting inherently safer chemical pathways (e.g., catalytic vs. non-catalytic).
- Choosing aqueous systems over solvent-based reactions.
- Reducing exothermicity to moderate runaway potential.
- Operating Condition Moderation:
- Reducing pressure: low-pressure distillation with vacuum systems.
- Lowering temperature: cryogenic separations vs. high-temperature cracking.
- Designing to minimize flammable/explosive ranges (e.g., inerting strategies).
- Simplification of Unit Operations:
- Avoiding unnecessary recycle loops that add complexity.
- Standardizing equipment to reduce unique failure modes.
- Simplifying startup/shutdown sequences to reduce operator error.
Afternoon Session: Equipment and Layout Design
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- Equipment-Level ISD:
- Vessels and tanks:
- Use of double-walled tanks for cryogenics, and
- Vertical vs. horizontal orientation for inherent containment.
- Piping systems:
- Minimizing dead-legs to reduce corrosion, and
- Sectionalizing with isolation valves to reduce inventory in failure scenarios.
- Plant Layout Considerations:
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- Inherent separation of hazardous units (distancing, segregation).
- Domino effect reduction: firewalls, blast walls, and layout spacing.
- Locating occupied buildings outside hazard zones.
- Modeling and Analysis:
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- Use of CFD for vapor cloud dispersion and explosion overpressure.
- Quantitative comparison of layouts for inherent safety improvements.
- Workshop Exercise:
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- Re-designing a compressor station:
- Apply ISD layout spacing principles
- Select simpler piping arrangements, and
- Validate improvements using CFD outputs.
Day 4 – Lifecycle Integration and Human Factors
Morning Session: ISD Across the Plant Lifecycle
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- Design Phase Integration:
- Embedding ISD at FEED: early selection of safer processes
- Conceptual design reviews with ISD checklists.
- Trade-offs between ISD and capital cost.
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- Operational Phase:
- Monitoring ISD performance indicators during operation.
- Preventing hazard reintroduction through poor modifications.
- Linking ISD to Management of Change (MOC) systems.
- Maintenance and Decommissioning:
- Designing for maintainability (ease of access, fewer confined spaces).
- Reducing exposure to hazardous energy during maintenance.
- ISD considerations for safe dismantling and decommissioning.
Afternoon Session: Human & Organizational Dimensions
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- Human Factors and Simplification:
- Reducing operator dependence through inherently reliable design.
- Ergonomic considerations in control room design.
- Designing alarms and human–machine interfaces to avoid overload.
- Digital ISD Applications:
- Cybersecurity as an inherent design element in safety instrumented systems.
- Simplification of digital control architectures.
- Case Study Analysis:
- LNG facility design:
- Cryogenic hazards and inventory minimization, and
- Human-factor considerations in emergency response.
- Workshop Exercise:
- Evaluate a process modification scenario:
- Identify hazard reintroduction risks, and
- Propose ISD countermeasures to simplify and reduce hazards.
Day 5 – ISD Implementation and Governance
Morning Session: ISD Implementation Roadmap
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- Policies and Governance Structures:
- Embedding ISD into company safety management systems.
- Defining accountabilities for ISD in project teams.
- Role of leadership in enforcing ISD principles.
- Design Reviews and Decision Gates:
- Gate reviews (Concept, FEED, Detailed Design, Commissioning.
- Embedding ISD checklists in HAZOP/LOPA/QRA studies.
- Decision-making frameworks: balancing ISD vs. engineered safeguards.
- Tools and Frameworks:
- ISD checklists for project reviews.
- Scoring systems for prioritization of ISD opportunities.
- Integration with lifecycle cost-benefit analyses.
Afternoon Session: Assurance and Continuous Improvement
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- ISD Auditing & KPIs:
- Key metrics: inventory reduction, substitution achieved, simplification applied.
- Auditing ISD across project lifecycle.
- Independent verification of ISD application.
- Continuous Improvement:
- Lessons learned from global incidents where ISD failed or succeeded.
- Feedback loops into new projects (knowledge management systems).
- Final Workshop:
- Develop a 12-month ISD improvement plan for a case study plant:
- Identify top 5 ISD interventions
- Assign roles, responsibilities, and milestones
- Define ISD KPIs and tracking mechanisms, and
- Present roadmap to class for peer review.