AI Quick Summary

Detailed timeline guide for MHI risk assessments in South Africa, covering each phase duration, factors affecting timeline, and how to plan effectively.

MHI Assessment Timeline: How Long Does It Take?

One of the first questions facility managers ask is: "How long will the MHI assessment actually take?" The answer depends on facility size, complexity and documentation.
This article gives realistic timelines so you can plan properly:

  • Typical overall duration for small, medium and large facilities.
  • Week‑by‑week phases from engagement to final report.
  • Key factors that speed up or delay the work.
  • Practical tips to keep your project on schedule.

Typical MHI Assessment Timeline

Standard Timeline: 10-12 Weeks

Small to Medium Facilities:

  • Total duration: 10-12 weeks
  • HAZOP sessions: 5-10 days
  • From engagement to final report
    Large/Complex Facilities:
  • Total duration: 16-20 weeks
  • HAZOP sessions: 15-30 days
  • Additional modeling and analysis time

Phase-by-Phase Timeline

Phase 1: Pre-Assessment Planning (Week 1)

Duration: 1 week
Activities:

  • AIA selection and engagement
  • Scope definition
  • Team formation
  • Project planning
  • Budget approval
    Deliverables:
  • Engagement contract
  • Project plan
  • Team roster
  • Schedule
    Tips to Expedite:
  • Pre-qualify AIAs
  • Have budget approved
  • Identify team early

Phase 2: Information Gathering (Weeks 1-3)

Duration: 2-3 weeks (overlaps with Phase 1)
Activities:

  • Document compilation
  • P&ID updates
  • Procedure review
  • Chemical inventory verification
  • Historical data gathering
    Deliverables:
  • Complete documentation package
  • Updated P&IDs
  • Chemical inventory
  • Procedures
    Common Delays:
  • Outdated P&IDs (add 2-4 weeks)
  • Missing documentation (add 1-2 weeks)
  • Incomplete procedures (add 1-2 weeks)
    Tips to Expedite:
  • Start documentation update early
  • Assign dedicated coordinator
  • Prioritize P&ID updates

Phase 3: Site Familiarization (Weeks 3-4)

Duration: 1-2 days
Activities:

  • Site tour
  • Process walkthrough
  • Personnel interviews
  • Facility observation
  • Photography
    Deliverables:
  • Site visit report
  • Preliminary observations
  • Clarification questions
    Tips to Expedite:
  • Schedule during documentation phase
  • Arrange access in advance
  • Have knowledgeable guide

Phase 4: Hazard Identification - HAZOP (Weeks 4-6)

Duration: 1-3 weeks (depending on complexity)
Small Facility (5-7 days):

  • 10-15 nodes
  • 1-1.5 weeks
  • 2 sessions per day
    Medium Facility (10-15 days):
  • 20-30 nodes
  • 2-3 weeks
  • 2 sessions per day
    Large Facility (20-30 days):
  • 40-60+ nodes
  • 4-6 weeks
  • 2 sessions per day
    Factors Affecting Duration:
  • Process complexity
  • Number of nodes
  • Team availability
  • Documentation quality
    Common Delays:
  • Team member absences (add 20-30%)
  • Documentation issues (add 10-20%)
  • Scope changes (add 1-2 weeks)
    Tips to Expedite:
  • Ensure team availability
  • Limit session interruptions
  • Stay focused on scope

Phase 5: Risk Analysis (Weeks 6-8)

Duration: 2-3 weeks
Activities:

  • Consequence modeling
  • Fire modeling
  • Explosion modeling
  • Toxic dispersion modeling
  • Likelihood assessment
  • Risk ranking
    Deliverables:
  • Modeling results
  • Risk rankings
  • Scenario analysis
    Factors Affecting Duration:
  • Number of scenarios
  • Modeling complexity
  • Software availability
  • Data availability
    Tips to Expedite:
  • Prioritize critical scenarios
  • Use appropriate tools
  • Have data ready

Phase 6: Risk Evaluation (Week 8)

Duration: 1 week
Activities:

  • Risk acceptability assessment
  • Comparison to criteria
  • Gap identification
  • Prioritization
    Deliverables:
  • Risk evaluation summary
  • Priority rankings
  • Gap analysis

Phase 7: Recommendations (Weeks 8-9)

Duration: 1-2 weeks
Activities:

  • Recommendation development
  • Hierarchy of controls application
  • Prioritization
  • Implementation guidance
  • Cost-benefit considerations
    Deliverables:
  • Recommendation register
  • Priority rankings
  • Implementation guidance

Phase 8: Report Preparation (Weeks 9-10)

Duration: 2-3 weeks
Activities:

  • Draft report writing
  • Internal review
  • Quality assurance
  • Graphics and formatting
    Deliverables:
  • Draft report
  • HAZOP worksheets
  • Modeling results
  • Appendices
    Tips to Expedite:
  • Document during HAZOP
  • Use templates
  • Parallel activities

Phase 9: Review and Finalization (Weeks 11-12)

Duration: 2-3 weeks
Activities:

  • Client review
  • Management presentation
  • Comment incorporation
  • Final report issuance
    Deliverables:
  • Final report
  • Presentation materials
  • Regulatory submission package
    Common Delays:
  • Extended client review (add 1-2 weeks)
  • Multiple revision rounds (add 1-2 weeks)
  • Management scheduling (add 1 week)
    Tips to Expedite:
  • Set review deadlines
  • Limit revision rounds
  • Schedule presentation early

Timeline by Facility Type

Chemical Manufacturing

Small Plant:

  • Timeline: 10-12 weeks
  • HAZOP: 5-10 days
  • Complexity: Moderate
    Medium Plant:
  • Timeline: 12-16 weeks
  • HAZOP: 10-20 days
  • Complexity: High
    Large Plant:
  • Timeline: 16-24 weeks
  • HAZOP: 20-40 days
  • Complexity: Very high

Oil & Gas Refineries

Small Unit:

  • Timeline: 12-14 weeks
  • HAZOP: 10-15 days
  • Complexity: High
    Medium Refinery:
  • Timeline: 16-20 weeks
  • HAZOP: 20-30 days
  • Complexity: Very high
    Large Refinery:
  • Timeline: 20-30 weeks
  • HAZOP: 30-50 days
  • Complexity: Extremely high

Mining & Mineral Processing

Small Operation:

  • Timeline: 8-10 weeks
  • HAZOP: 5-8 days
  • Complexity: Moderate
    Medium Operation:
  • Timeline: 10-14 weeks
  • HAZOP: 10-15 days
  • Complexity: Moderate to high
    Large Operation:
  • Timeline: 14-20 weeks
  • HAZOP: 15-25 days
  • Complexity: High

FMCG / Cold Storage

Small Facility:

  • Timeline: 8-10 weeks
  • HAZOP: 3-5 days
  • Complexity: Low to moderate
    Medium Facility:
  • Timeline: 10-12 weeks
  • HAZOP: 5-10 days
  • Complexity: Moderate
    Large Facility:
  • Timeline: 12-16 weeks
  • HAZOP: 10-15 days
  • Complexity: Moderate to high

Factors Affecting Timeline

1. Facility Complexity

Simple:

  • Standard processes
  • Few interconnections
  • Well-documented
  • Shorter timeline
    Complex:
  • Multiple units
  • Extensive interconnections
  • Specialized equipment
  • Longer timeline
    Impact: +50% to +200% for high complexity

2. Documentation Quality

Good Documentation:

  • Current P&IDs
  • Complete procedures
  • Available data
  • Faster progress
    Poor Documentation:
  • Outdated drawings
  • Missing information
  • Delays and rework
  • Extended timeline
    Impact: +20% to +50% for poor documentation

3. Team Availability

Consistent Availability:

  • All members present
  • Focused sessions
  • Efficient progress
    Availability Issues:
  • Members missing
  • Repeated discussions
  • Extended timeline
    Impact: +20% to +40% for availability issues

4. Scope Changes

Well-Defined Scope:

  • Clear boundaries
  • No surprises
  • On schedule
    Scope Creep:
  • Expanding boundaries
  • Additional areas
  • Timeline extension
    Impact: +10% to +30% for scope changes

5. Urgency

Normal Timeline:

  • Adequate preparation
  • Proper scheduling
  • Quality outcomes
    Rushed Timeline:
  • Compressed phases
  • Potential quality issues
  • Higher stress
    Impact: Can compress by 20-30% but risks quality

How to Minimize Timeline

Before Assessment

1. Plan Early (6-8 weeks ahead):

  • Engage AIA early
  • Update documentation
  • Form team
  • Secure budget
    2. Prepare Documentation:
  • Update P&IDs first
  • Compile procedures
  • Verify inventory
  • Gather historical data
    3. Secure Resources:
  • Team availability
  • Management commitment
  • Budget approval
  • Facilities

During Assessment

4. Maintain Focus:

  • Stay on scope
  • Limit interruptions
  • Manage time
  • Document efficiently
    5. Ensure Availability:
  • Team commitment
  • Backup personnel
  • Minimize absences
  • Schedule appropriately
    6. Communicate Effectively:
  • Regular updates
  • Quick decisions
  • Address issues promptly
  • Maintain momentum

After Assessment

7. Review Promptly:

  • Set deadlines
  • Provide feedback quickly
  • Limit revision rounds
  • Make decisions
    8. Plan Implementation:
  • Start planning early
  • Allocate resources
  • Track progress
  • Close loop

Realistic Planning

Best Case Scenario

Ideal Conditions:

  • Perfect documentation
  • Full team availability
  • No scope changes
  • Efficient execution
    Timeline: Minimum realistic duration
    Probability: 10-20% of projects

Typical Scenario

Normal Conditions:

  • Good documentation
  • Mostly available team
  • Minor issues
  • Standard execution
    Timeline: Standard duration
    Probability: 60-70% of projects

Worst Case Scenario

Challenging Conditions:

  • Poor documentation
  • Availability issues
  • Scope changes
  • Multiple delays
    Timeline: Extended duration (+30-50%)
    Probability: 10-20% of projects

Planning Recommendation

Add Buffer:

  • Plan for typical scenario
  • Add 20% buffer
  • Communicate realistic timeline
  • Manage expectations

MMRisk Timeline Commitment

Our Standard Timeline

Small to Medium Facilities:

  • 10-12 weeks typical
  • Clear milestones
  • Regular updates
  • On-time delivery
    Large/Complex Facilities:
  • 16-20 weeks typical
  • Phased approach
  • Progress tracking
  • Managed expectations

Our Process

Efficient Execution:

  • Experienced facilitators
  • Proven methodology
  • Quality documentation
  • Timely delivery
    Communication:
  • Regular updates
  • Issue escalation
  • Milestone tracking
  • Transparency

Conclusion

MHI assessment timelines vary based on facility complexity, documentation quality, and team availability. Typical timelines range from 10-20 weeks, with proper planning and execution being key to staying on schedule.
Understanding realistic timelines helps with planning, budgeting, and managing stakeholder expectations.
Need help planning your MHI assessment timeline? Contact MMRisk for realistic scheduling and efficient execution.

MMRisk: Efficient MHI assessments delivered on time across South Africa.