Hazard identification according to ISO 12100: an engineering-first guide to safer machines

Hazard identification according to ISO 12100 sits at the core of every credible machine risk assessment. When you apply the standard the way it was intended—systematically and with an engineering-first mindset—you reduce risk as far as reasonably practicable without sacrificing the machine’s function, usability, or viability. This article walks you through how to prepare, execute, and use hazard identification to drive effective, documented, and legally robust risk reduction.

Why risk reduction starts with Hazard identification according to ISO 12100

ISO 12100 defines general design principles and the risk assessment process for machinery. The objective is simple to state but demanding in practice: reduce risk as far as practically achievable while keeping the machine functional, usable, and economically feasible. The standard organizes risk reduction around four drivers in a deliberate order—an order you should mirror in every decision:

• Safety through the entire life cycle – Design, build, operate, service, and decommission the machine so that people stay safe at every stage, from installation to disposal.
• Ability to perform the intended function – Safety measures must not cripple the task the machine was built to do. If it cannot perform its function, users will bypass safeguards.
• Usability and ergonomics – Operators must work efficiently and comfortably. Overly burdensome protections invite circumvention; well-designed ones guide correct behavior.
• Costs of implementation, operation, and end‑of‑life – Aim for risk reduction that delivers value over the machine’s lifetime, including maintenance and decommissioning.

Put safety first and cost last. Then iterate. After you implement protective measures, reassess. If risk remains too high, add better safeguards and reassess again. Repeat until the residual risk meets your acceptance criteria. This iterative loop, grounded in state‑of‑the‑art technology and sound engineering practice, yields machines that are safe, effective, and legally credible. At the time of writing, ISO 12100 confers presumption of conformity under the Machinery Directive 2006/42/EC; a revision intended to support Regulation (EU) 2023/1230 is in preparation.

The ISO 12100 risk assessment workflow

A risk assessment under ISO 12100 comprises analysis and evaluation. In practice, you will work through four major steps: define the machine limits; perform hazard identification; estimate risk; evaluate risk. You only select and implement protective measures after you complete the analysis and determine what must change to reach an acceptable residual risk. Because the quality of every later step depends on what you identify upfront, this article focuses on the mechanics of high‑fidelity hazard identification.

Information sources for Hazard identification according to ISO 12100

Prepare before you identify hazards. Collect the information that sets your scope and prevents blind spots:

• Machine documentation and user requirements – Functional description, intended use, operating modes, technical specifications, drawings, bills of materials, utilities, and performance expectations from stakeholders.
• Applicable legislation and standards – The base standard (ISO 12100) and relevant type‑B and type‑C standards (control system safety, electrical equipment, ergonomics, noise, fluids, flammables, powders, and any sector‑specific documents). This corpus frames mandatory and state‑of‑the‑art protective measures.
• Operational experience with similar machines – Accident and near‑miss histories, service data, failure statistics, misuse patterns. Absence of past incidents does not prove low risk; it may indicate luck or underreporting.
• Ergonomic and environmental context – Who will operate and service the machine, in which postures, and under which conditions (indoor/outdoor, temperature, humidity, dust, lighting, weather, hygiene). These factors both generate hazards and influence the effectiveness of safeguards.

Keep this information live and current as the design evolves. It will drive a more accurate picture of hazards and hazardous situations across the machine life cycle.

Defining machine limits (Step 1)

Start by defining the machine’s limits—the boundaries within which your assessment holds. You will examine four dimensions: use, space, time, and other constraints that stem from materials and environment.

• Limits of use – Specify the intended use and the reasonably foreseeable misuse. Map operating modes (automatic, manual, teach, service), interventions during jams or faults, and the user population (trained operators, maintenance technicians, contractors, trainees, visitors). Account for human characteristics that influence safety—training, experience, stature, handedness, and possible impairments.
• Spatial limits – Define motion envelopes of moving parts, hazardous zones, and safe access paths. Ensure adequate operator and maintenance space for every task. Verify human‑machine interfaces, visibility, reach, and utilities routing so that cables, hoses, and ducts do not introduce tripping or snagging risk.
• Time limits – Establish the life expectancy of the machine and its subsystems, duty cycles, and preventive maintenance intervals. Frequency of exposure matters; intensive, multi‑shift operation increases risk without robust design and maintenance.
• Other constraints – Consider processed materials and process media (toxic, corrosive, flammable, sharp, heavy, hot, cold), cleanliness and wash‑down requirements, and environmental conditions (temperature, humidity, dust, weather, explosive atmospheres). These conditions affect both hazard creation and the durability of safeguards.

This context anchors every subsequent decision. With the limits defined, you can now identify hazards with precision.

Systematic Hazard identification according to ISO 12100 (Step 2)

Hazard identification means listing all credible sources of harm, the hazardous situations in which a person may be exposed, and the hazardous events that can lead to injury or damage. ISO 12100 requires you to cover every life‑cycle phase: transport, installation, commissioning, testing, normal operation, setup and changeover, cleaning, fault clearance and restart, maintenance, decommissioning, and dismantling. Each phase introduces different risks; cover them all.

Tasks and human–machine interactions across the lifecycle

Map what the machine does and what people do around it. Build a task list and study each activity step by step. Then ask, for every step: what could go wrong, what could a person contact, and how could harm occur?

• Setting and adjustment – Configuring parameters, jogging axes to reference positions, calibrations.
• Testing and trial runs – Dry cycles, subsystem tests, controller programming, robot teaching and path verification.
• Changeover – Tooling changes, re‑fixture, product format change; often performed in the hazard zone.
• Start‑up and normal operation – Routine production, feeding and removing parts, supervision, minor interventions.
• Feeding and take‑off – Loading materials and removing products or scrap; many injuries occur at this interface.
• Stopping – Normal stop and emergency stop; consider run‑down of moving parts and stored energy release.
• Clearing jams and restarting – Fault recovery under time pressure; risky if restart can occur unexpectedly.
• Troubleshooting and service – Diagnostics, adjustments, replacements, lubrication, and calibration involving guard removal or lockout.
• Cleaning and housekeeping – Wash‑down, vacuuming, removing swarf and waste; chemicals and confined access often change risk profiles.
• Preventive and corrective maintenance – Periodic inspection and fix‑on‑fail repairs, sometimes with temporary measures that bypass protections.

Write simple, structured scenarios. One effective pattern is: during [task] + [hazard source] may lead to [consequence]. For example: during setup, sharp edges may cause a laceration. You will later assign probability and severity to each scenario to calculate risk and decide on risk reduction priorities.

Use experience aggressively. Consult seasoned operators and maintenance technicians; they see real‑world behaviors and failure modes that design teams often miss. Supplement interviews with checklists from standards and technical reports—Annexes that list typical hazards can act as prompts to prevent omissions. Software or structured templates help enforce completeness, but they do not replace engineering judgement or on‑site observation.

Typical hazard categories to screen

Once you map tasks and situations, screen for the recurring hazard families that appear in industrial machinery:

• Mechanical – Entanglement, drawing‑in, crushing, shearing, impact from moving parts (shafts, gears, belts, conveyors, presses, robot arms), trapping in gaps, ejected parts, and instability or collapse.
• Electrical – Electric shock, arc flash, static discharge, insulation failure, inadequate bonding and grounding, and fire from short circuits.
• Thermal – Burns from hot surfaces and fluids, frostbite from cryogenic media, ignition risk from high temperatures, and radiant heat exposure.
• Chemical – Toxic or corrosive substances, solvents, coolants, fumes, mists, dusts and powders; normal emissions and accidental releases (e.g., high‑pressure leaks).
• Radiation – Laser beams, UV from curing and welding, ionizing radiation in inspection equipment, and strong electromagnetic fields that may affect medical implants.
• Noise and vibration – Hearing damage, degraded communication, fatigue, and hand‑arm or whole‑body vibration effects.
• Ergonomics – Awkward postures, excessive force, repetitive motions, poor reach and visibility, and lighting deficiencies that increase error likelihood.

Beyond normal operation: faults, abnormal states and human error

Do not stop at nominal conditions. Consider single faults, software defects, power dips, component wear, external disturbances, and design oversights. Ask: if the machine fails to perform as intended, what happens? Do axes stop safely or drift? Do fragments eject if a tool breaks? Does material back up and prompt manual intervention? Also consider predictable human behavior under pressure: time‑saving shortcuts, routine‑induced complacency, distraction, and deliberate override of protections. If a person can enter a hazardous zone during operation, plan as if someone eventually will. These scenarios are real hazards that require risk reduction.

Standards evolve. ISO 12100 currently underpins conformity with Directive 2006/42/EC. A revision intended to support Regulation (EU) 2023/1230 is anticipated around 2026, likely with guidance on digital and cybersecurity‑related hazards.

Team composition and review for Hazard identification according to ISO 12100

Build a cross‑functional team: design engineers, controls specialists, operators, maintenance, and EHS professionals. For rigorous severity assessments, involve occupational health expertise when needed. After you draft the hazard list, perform an independent review or benchmark it against similar machines to catch omissions before you move to risk estimation.

What happens after Hazard identification according to ISO 12100?

The output of hazard identification is a structured list of hazards, hazardous situations, and events, each tied to the tasks and contexts in which exposure occurs. You now estimate risk for every scenario by combining severity, frequency/exposure, and the probability of occurrence or avoidance. Then you evaluate these risks against your acceptance criteria to decide which ones demand further reduction and in what order.

When you reduce risk, apply the three‑step method: first, inherently safe design measures; second, technical and complementary protective measures (guards, interlocks, functional safety functions); third, information for use (signage, instructions, training, PPE) to cover residual risks. Each iteration should bring the machine closer to the target residual risk while preserving function and usability.

Document everything. ISO 12100 expects a traceable record: limits and assumptions, identified hazards and scenarios, the risk ratings before and after measures, and the rationale for acceptability. This file supports CE marking, audits, and future modifications. Treat hazard identification as a living process. Update it after design or software changes, process or layout changes, incidents and near misses, or the publication of new standards. Periodic risk reviews and machine safety audits will keep your assessment relevant and your protections effective.

Executed with discipline, Hazard identification according to ISO 12100 delivers safer designs, fewer incidents, and smoother operations. It empowers teams to foresee harm before it manifests, engineer it out where possible, and protect people where it is not. In short: safety starts with seeing the hazards clearly—and acting on them.

FAQ