Welcome
From hazard identification to risk control
Welcome to Lesson 05 of Component 12. This lesson develops your understanding of the full risk assessment process.
You will move from identifying hazards using HAZID and HAZOP, to evaluating likelihood and consequence, calculating risk scores, and choosing suitable controls.
How can an engineer turn a hazard they can see into a clear, evidence-based decision about what control is needed?
Learning Outcomes
What should you know by the end?
Prior Knowledge Check
Hazard, risk and control
Why This Matters
Risk assessment is at the heart of safe engineering
Engineers regularly work with machinery, electrical systems, stored energy, hazardous substances and changing work environments. Before work begins, the risks to the engineer and to others must be assessed.
A good risk assessment helps decide whether existing controls are enough or whether further action is required before the task continues.
A lathe has a known guarding problem. Would simply issuing PPE make the task safe enough? Explain why or why not.
Main Learning Content
The risk assessment process
Key Definitions
Stages of Risk Assessment
- Hazard identification (HAZID).
- Hazard and operability study (HAZOP), where appropriate.
- Evaluate risk using likelihood and consequence.
- Implement control measures.
- Record significant findings.
- Review and revise the assessment when necessary.
HAZID
Hazard identification is the first stage of risk analysis. Engineers identify activities, equipment, substances and conditions that could cause harm.
Equipment and tools • Stored energy • Electricity • Harmful substances and gases • Environment
HAZOP
A hazard and operability study is a structured and systematic technique used to identify and evaluate potential safety hazards within a process or system.
Risk Score
A common approach is: Risk score = Likelihood × Consequence. The score is then interpreted using a risk matrix.
Hierarchy of Controls
- Eliminate the hazard where possible.
- Substitute with something less hazardous.
- Engineering controls such as guards or extraction.
- Administrative controls such as procedures and training.
- PPE as the final line of defence.
Lesson Presentation
Teacher-led learning • PowerPoint 5
Risk Assessment
Use PowerPoint 5 for the teacher-led explanation of HAZID, HAZOP, likelihood, consequence, risk matrices and the hierarchy of controls.
▶ Open Lesson PresentationYour Lesson 05 PowerPoint or PDF will be connected here when it is uploaded.
Engineering Case Study
Evaluating a real engineering risk
Machine Operator Using a Lathe Without a Chuck Guard
A machine operator is asked to use a metal lathe, but the chuck guard is missing. The rotating chuck can catch clothing, strike the operator or eject material.
Discuss
- What is the hazard?
- Who could be harmed?
- How likely is an incident?
- How severe could the consequence be?
- What controls would lower the risk?
A strong answer links the hazard, the possible consequence and the selected control rather than simply naming PPE.
Risk Assessment Activity
Calculate, justify and control risk
Robot Arm Scenario
An engineer needs to make an adjustment to an industrial robot arm that has not been electrically isolated.
Check examiner-style mark guidance
Indicative marking points:
- Identifies stored/electrical energy as a hazard.
- Recognises possible movement of the robot arm.
- Considers likelihood of contact or unexpected movement.
- Considers severity of possible injury.
- Recommends isolation / lock-off before adjustment.
- Explains how the selected control reduces risk.
For higher-quality answers: justify the control using the hierarchy of controls, not only PPE.
Lesson Summary
Risk assessment in six steps
Identify
Use HAZID to identify hazards before exposure occurs.
Evaluate
Consider likelihood and consequence to determine the level of risk.
Control
Use the hierarchy of controls, prioritising stronger controls over PPE.
Review
Record findings and revise the assessment when the task or conditions change.
Exit Ticket
Check your risk assessment understanding
Check answer guidance
Q1: A hazard is a source of potential harm; risk considers the likelihood and consequence of that harm occurring.
Q2: HAZID is used to identify potential causes of harm before or during risk analysis.
Q3: Stronger controls act on the hazard itself, while PPE relies on correct selection, use and behaviour and does not remove the hazard.
Complete Worksheets 6, 7 and 8 to practise HAZID, risk evaluation and the hierarchy of controls.
Risk Assessment Worksheets
Worksheets 6, 7 and 8
Worksheet 6: Hazard Identification (HAZID)
Work through the HAZID mind-map activity and identify hazards linked to equipment and tools, stored energy, electricity, harmful substances and the environment.
Worksheet 7: Evaluation of Risks
Use likelihood and consequence tables together with a risk matrix to calculate and justify risk scores for engineering scenarios.
Worksheet 8: Hierarchy of Controls
Apply the hierarchy of controls and decide which controls are most effective for reducing engineering risks.
You should now be able to identify hazards, calculate a risk score and select controls using the hierarchy of controls.
AI Lesson Companion
Future VITHAAA learning support
Ask VITHAAA AI
Students will eventually be able to ask questions about HAZID, HAZOP, likelihood, consequence, risk matrices and control measures here.