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.
Risk assessment, HAZOP, hazard assessment: not the same thing
- 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 risk analysis method, defined in EN 61882 and particularly suited to the chemical and power plant industries. HAZOP alone does not fulfil the legal requirement: it covers the risk analysis, not the risk evaluation.
- Workplace hazard assessment: concerns the operation of a facility after it has been placed on the market and is the employer's duty.
The process
- Risk analysis: hazards are identified within defined limits.
- Risk evaluation: each hazard is assessed for severity of harm and probability of occurrence.
- Decision: is the risk sufficiently low? If not, risk reduction measures follow, and the process is repeated to verify them.
EN ISO 12100 provides a procedure tailored to machinery and is applied in practice together with ISO/TR 14121-2, a practical guide to implementation.
What is risk?
Risk is not a feeling. It is the combination of the probability of occurrence and the severity of harm. Two related terms matter:
- Acceptable risk: the risk deemed tolerable based on current societal values.
- Residual risk: the risk that remains despite all protective measures. It must be described in the instructions.
The three-step method
If a risk is too high, the standard prescribes a fixed order of measures:
- Inherently safe design
- Technical protective measures: guards, protective devices, safety functions with the required Performance Level or SIL
- Information for use: guidance on safe use, personal protective equipment, training
This order is binding. Step 3 must not replace missing design or technical solutions.
Why documentation decides legal certainty
In the event of personal injury, manufacturers, designers and those placing products on the market face potential criminal consequences, particularly where negligence or missing warnings can be shown. Thorough documentation of the risk assessment is the decisive evidence that the process was carried out correctly.
A free Excel template for machinery risk assessment per ISO/TR 14121-2, covering all seven life-cycle phases, is available on the German download page (currently in German only). The complete methodology is in the e-book CE marking in plant engineering.
This article is a technical working aid. It does not replace reading the legal texts or individual advice.