In Process Safety and Loss Prevention, Hazard and Risk are two basic and important concepts.
What is Hazard?
A Hazard is something that has the potential to cause harm.
Examples:
- Flammable material
- Toxic material
- High pressure
- High temperature
- Reactive chemicals
- Stored energy
What is Risk?
Risk is the potential for a hazard to result in an unwanted consequence.
A simple way to understand it is:
Risk = Hazard × Consequence
However, in a more practical process safety context, risk is generally considered as:
Risk = Likelihood × Consequence
Where:
- Hazard = What can cause harm?
- Likelihood = How likely is it to happen?
- Consequence = How severe could the outcome be?
- Risk = Overall significance of the scenario
Simple Example
Consider a high-pressure flammable gas pipeline.
Hazard:
Flammable gas at high pressure.
Event:
Pipeline leak.
Consequence:
Fire, explosion, injury or equipment damage.
Risk:
The likelihood of the leak and subsequent event combined with the severity of the consequence.
So, in simple terms:
Hazard = Potential to cause harm
Risk = Likelihood × Consequence
This simple distinction is the foundation of many Process Safety studies such as HAZID, HAZOP, QRA, SIL Assessment and Bow-Tie Analysis.
