Heinrich’s traditional 5 Domino Theory on accident causation is the standard model used by health and safety professionals.

/ Exams & Certification / By

QUESTION 1 Heinrich’s traditional 5 Domino Theory on accident causation is the standard model used by health and safety professionals. This, he says is the way with workplace health and safety, where one undesirable event in the workplace will lead to others, and eventually to an accident. a) Illustrate Heinrich’s Domino Theory by giving an example if accident occur. 14 Marks b) Heinrich felt that the person responsible at a company for loss control should be interested in all factors, but be concerned primarily with accidents and the proximate causes of those accidents. Base on the reason, he came out with the corrective action. Describe THREE (3) corrective action sequences that implement in Henrich’s Domino Theory. 16 Marks c) A case study 2005, Texas City in Oil refinery explosion was cause 15 killed and 180 injured and estimated US$2 billion lost. As a safety officer, plan the costs that involve direct, indirect and investigation of the accident. 15 Marks QUESTION 2 Chemical industries have enriched our live and involve a lot of complex processes. More complex processes require more complex safety technology. Since 1950, significant technological advances have been made in chemical process safety. As chemical process technology becomes more complex, chemical engineers will need a more detailed and fundamental understanding of safety. a) Differentiate between a good safety program and outstanding safety program. 12 Marks b) A successful safety program requires SIX (6) ingredients. Describe and provide an explanation for each of the ingredients. [6 Marks) c) Chemical plants contain a large variety of hazards. Describe at least TWO (2) types of hazards in chemical plant and give an example for each type of the hazard. 12 Marks

The Correct Answer and Explanation is:

QUESTION 1

a) Heinrich’s Domino Theory Example (14 Marks)

Heinrich’s Domino Theory identifies five factors leading to accidents:

  1. Ancestry/Social Environment
  2. Fault of Person
  3. Unsafe Act/Mechanical or Physical Hazard
  4. Accident
  5. Injury

Example:
An untrained worker (1. poor background/training) becomes careless (2. personal fault), and neglects to wear PPE near machinery (3. unsafe act). The worker’s hand gets caught (4. accident), leading to a fracture (5. injury). Removing any of the dominoes prevents the final injury.

b) Three Corrective Action Sequences (16 Marks)

  1. Training and Education
    Improve worker behavior through skill-building and awareness. Training reduces unsafe acts by addressing personal faults.
  2. Engineering Controls and Safe Design
    Modify equipment or processes to eliminate hazards. For example, machine guards prevent contact with moving parts.
  3. Administrative Controls and Supervision
    Develop policies and enforce safety procedures. Effective supervision ensures compliance and timely hazard correction.

c) Cost Planning – Texas City Explosion Case Study (15 Marks)

As a safety officer, the cost breakdown includes:

  1. Direct Costs:
    • Medical treatment for injured (180 people)
    • Compensation to families of the 15 fatalities
    • Equipment damage and plant repair
  2. Indirect Costs:
    • Downtime and lost productivity
    • Employee morale decline and turnover
    • Legal fees and insurance premium increase
  3. Investigation Costs:
    • Forensic analysis and root cause investigation
    • Internal safety audits
    • Implementation of corrective actions and training

QUESTION 2

a) Good vs. Outstanding Safety Program (12 Marks)

  • Good Safety Program: Meets legal requirements, responds to incidents, provides basic training.
  • Outstanding Safety Program: Goes beyond compliance, integrates safety into culture, uses proactive risk assessment and continuous improvement.

Example: A good program might investigate accidents; an outstanding one prevents them through predictive analytics and active employee engagement.

b) Six Ingredients of a Successful Safety Program (6 Marks)

  1. Management Commitment
    Leadership actively supports and funds safety initiatives.
  2. Employee Involvement
    Workers participate in hazard identification and safety committees.
  3. Hazard Identification and Control
    Regular inspections and risk assessments are conducted.
  4. Training and Education
    Continuous safety education ensures all staff are competent.
  5. Accident Investigation
    Root cause analysis of incidents for learning and prevention.
  6. Monitoring and Continuous Improvement
    Safety performance is tracked, and programs evolve accordingly.

c) Two Types of Hazards in Chemical Plants (12 Marks)

  1. Chemical Hazards
    Example: Chlorine gas leak – causes respiratory harm and corrosion.
  2. Physical Hazards
    Example: High-pressure vessel explosion – leads to blast injuries or fire.

Understanding and controlling these hazards are vital for process safety.

Related Posts

Scroll to Top