Lecture 3 - Hazards and Controls

Question 1

What are hazards?

Answer 1

Hazards are a risk source, often classified into groups

Question 2

What is a control?

Answer 2

• A control is defined in ISO 31000:2018 as a “measure that maintains and/or modifies risk.”
  1. Note 1: controls include, but are not limited to, any process, policy, device, practice or other conditions and/or actions which maintain and/or modify risk.
  2. Note 2: controls may not always exert the intended or assumed modifying effect.
• There is a hierarchy of controls (see slides)
• Engineering Controls and assuring their performance standards are adhered to is a key focus in safety management systems.

Question 3

What are barriers?

Answer 3

Barriers are a type of ENGINEERING RISK CONTROL
* Aimed at separating people from the hazard
* Barriers can be tangible physical barriers (walls, pipes, cladding) or use distance from hazard to source, or provide shielding for the subject e.g. PPE, bunkers.

Question 4

How to identify challenges to engineering controls?

Answer 4

• Once controls are identified, the requirements for maintaining each barrier also needs to be identified.
• We need to identify what is needed to maintain the integrity of each barrier.
• This is because barriers can fail due to:
• Physical processes (deformation, erosion, corrosion, loss of toughness and yield strength, change in material properties, internal/ external forces.
• Malfunction of equipment.
• Human practices and decisions
• Poor design or maintenance
• Adverse natural phenomena
• And many other reasons….
• Our expectations about the performance of the barriers has to be tested

Question 5

How to establis consequences for failure of engineering controls

Answer 5

Consequence estimates are often complex and require an estimation of who and what is impacted and the nature of the impact.
* In some industries it is a requirement to use formal methods to identify hazards, scenarios, barrier, likelihood and consequence estimates.
* A practice in high hazard industries is quantitative risk assessment (QRA) which uses models and numbers to quantify both the likelihood and consequence of events.