Risk Assessment per EN ISO 12100: The Process Explained
Risk Assessment per EN ISO 12100: The Process Explained
Risk assessment is one of the central pillars of the CE conformity process. It is legally required – among others by the Machinery Directive and the Pressure Equipment Directive – and must be carried out by the manufacturer before a product is placed on the market. Skipping it or handling it superficially creates a real legal risk.
Risk Assessment, HAZOP, Hazard Assessment – Not the Same Thing
These terms are often used interchangeably in everyday language. For clarity:
Risk assessment – legally required, carried out by the manufacturer before placing the product on the market. For plant engineering, the basic safety standard EN ISO 12100 is the key reference.
HAZOP (Hazard and Operability) – a specific method for risk analysis, originally from the UK, defined in DIN EN 61882. It is particularly suited to the chemical and power plant industries. Important: HAZOP alone does not fulfil the legal requirement – it only covers the risk analysis, not the additionally required risk evaluation.
Workplace hazard assessment – not to be confused with a product risk assessment! It concerns the operation of a facility after it has been placed on the market and must be carried out by the employer.
The Process: Risk Analysis, Risk Evaluation, Decision
A risk assessment generally follows a series of interconnected steps:
Risk analysis – hazards are identified within defined limits.
Risk evaluation – each identified hazard is assessed for severity of harm and probability of occurrence.
Decision – is the risk sufficiently low? If not, risk reduction measures are required – and the entire process is repeated to verify those measures.
The standard EN ISO 12100 provides a procedure tailored to machinery and is applied in practice together with DIN ISO/TR 14121-2, which offers a practical guide to implementation.
What Is "Risk" Anyway – the Definition per Standard
Risk is not a subjective feeling but is defined as a numerical value:
Risk = Probability (frequency) × Severity of harm
This gives rise to two important related terms:
Acceptable risk – the risk that is deemed tolerable based on current societal values.
Residual risk – the risk that remains despite all protective measures. It must be described in the user manual.
Risk Reduction: The Three-Step Safety Concept
If a risk is assessed as too high, the standard prescribes a fixed order of countermeasures:
Inherently safe design – avoid hazards through the design itself (e.g. eliminating sharp edges, enclosing hazard sources).
Technical protective measures – when design solutions are insufficient: separating guards, sensitive protective equipment, defined safety functions with the corresponding Performance Level or SIL.
User information and work instructions – as a last resort: guidance on safe use, required personal protective equipment, training measures.
This order is not a recommendation but binding – step 3 must not be used as a substitute for missing design or technical solutions.
Why Documentation Determines Legal Certainty
In the event of personal injury, manufacturers, designers, or those placing products on the market face potential criminal consequences – particularly where negligence, violation of safety standards, or missing warnings can be proven. Clean, thorough documentation of the risk assessment is the decisive evidence that the process was carried out correctly – and thus the most effective protection against an accusation of negligence.
Free Excel Template for Risk Assessment
To make getting started easier, there is a free spreadsheet template for carrying out risk assessments of machinery per DIN ISO/TR 14121-2 – covering all seven usage phases of a machine (transport, assembly/installation, setup, operation, cleaning/maintenance, troubleshooting, decommissioning). Currently available in German.
For the complete methodology – including the HAZOP approach, SIL/Performance Level determination, and the full instructions for the template – the e-book "CE Marking in Plant Engineering" provides a step-by-step guide.
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