EN 17975:2025 and safety in maintenance operations. The HOT LoToTo solution.

Serious accidents occur every week during maintenance operations on installations. In this context, the European standard EN 17975:2025 has been published in order to reinforce the safety of maintenance work.

The objective of maintenance is to "maintain or restore the operation" of an installation or machine. This concept covers a wide range of activities:

• Routine maintenance (cleaning, adjustment, lubrication, etc.).
• Emergency repairs, corrective maintenance.
• Preventive maintenance, inspections.
• Improvement maintenance, modifications, new works.
• Etc.
  
  

These operations are carried out and managed by multiple actors, not only by the technical departments:

• General services (maintenance, facility management).
• Contractors, new works, design office (projects).
• External companies, project management (works).
• Operators, production teams (self-maintenance).
  

All of these players are exposed to risks during maintenance operations.

INSST data on accidents during maintenance operations show that the probability of serious accidents is 1.5 times higher than the national average, the probability of illness is 1.4 times higher and the fatality rate is 3.6 times higher.

Interacting with a machine during maintenance means exposure to the dangers associated with energy and fluids.

EN 17975:2025 provides guidelines and recommendations for controlling the risks associated with energy and fluids during maintenance operations.

More than 50% of the accidents that occur during maintenance work are due to poorly controlled energies and fluids (electrical, hydraulic, pneumatic, mechanical, steam, chemicals, etc.).

Three main types of causes must be addressed in order to take action in this regard:

• Human: qualifications, behavior and culture.
• Organizational: functions and tasks, procedures and processes.
• Technical: registration or traceability, compliance.
  
  

Beyond the simple concepts of Lo-To (Lock-Out, Tag-Out) or Lo-To-To (Lock-Out, Tag-Out, Try-Out), it is imperative to integrate these three types of risk through a global approach. At Apave, we call this approach "HOT LoToTo".

It is also essential not to consider the effects for a single workstation, but to contemplate (at the time) the tasks and activities that are performed with, on and around the machines and installations.

There are usually two types of accidents that are difficult to deal with in an industrial environment:

• Accidents of high frequency and moderate severity, such as falls from the ground, which often need to be addressed by acting on OHS management, safety culture and the adoption of good habits.
• High severity, low frequency accidents, related to inadequate energy control during maintenance and overhaul operations.
  
  

From a regulatory point of view, before the publication of the NF X60-400 standard (replaced by the European standard EN 17975:2025), maintenance professionals only had the NF C18-510 standard on electricity and the Labor Code, or its equivalents in Spain, the REBT and the LPRL.

The Machinery Directive, for its part, guarantees operational safety and routine maintenance, but only addresses the issue of exceptional maintenance in a very general way. In addition, often the conformity established by the supplier is no longer valid, because the installation has been modified over time, its use has changed, the way of organizing the work is different (e.g. introduction of self-maintenance), etc.

When the question of safe intervention in a maintenance operation arises, it is important to consider all the energies and fluids involved, not only electricity. When applying the procedure, all the direct and indirect occupational hazards associated with energy and fluids must be taken into account. These are the elements necessary to define the most effective safety measures. Drawing up a checklist as a key to the systematic analysis of risks before each maintenance situation is a good practice to adopt.

The usual difficulties and causes of the lack of control of these risks in maintenance are as follows:

• Lack of information (e.g. outdated plans), standards and procedures.
• Communication failures (e.g. between production and maintenance teams, in the transmission of instructions between teams, etc.).
• Obsolete facilities.
• Accessibility problems.
• Design and compliance problems (and uncontrolled modifications).
• Unreliablesafety devices and locking mechanisms.
• Lack of maintenance (e.g., absence of a preventive plan for equipment or safety devices).
• Misconceptions (pushing an emergency stop button does not necessarily make the worker safe if energy flows are not taken into account).
  
  

Safety does not depend solely on technical considerations. Organizational and human factors play an important role.

When it comes to maintenance, a quick solution must be found so as not to delay the production flow too much. In emergency repairs, 80% of the safety of maintenance operations often depends on the behavior of the operators.

These maintenance operations are particularly prone to accidents. Sometimes chronically understaffed due to market shortages, maintenance operators are often overworked, performing on-call and overtime. The pressure of daily work, combined with the challenge of safety, is a difficult equation. Even in the ideal company, the maintenance operator is often burdened with the pressure, because his job is to help others. Accidents in which a witness tells us that the victim behaved in a risky manner "to serve" are, unfortunately, commonplace.

Everyone's behavior is an equation resulting from the individual, but also from the company culture, the practices of those in charge and the organization. There are two types of "risky" behavior profile: the novice (high frequency of accidents, low severity) and the expert, who has become accustomed to risk and suffers few accidents, but of high severity. We should be inspired by firefighters, who are trained and have systematic protocols for approaching risk so as not to give in to pressure and make a mistake, interspersed with a systematic "stop" to take a step back and analyze the risk before each intervention.

It is also essential to establish a general procedure for securing energy and fluids, setting the level of demand and defining standards. It must be coordinated with the company's other processes and standards, and address a wide range of situations (external contractors, shift changes, etc.).

Production, as a partner in maintenance, must be involved in the process, as must management. Long-term management involvement is crucial to success.

For scheduled operations (usually preventive maintenance), it is possible to optimize both machine downtime and safety through preparation. The Apave approach stresses the importance of returning to good maintenance practices (relationship between planned and unplanned maintenance, methods, reliability, maintainability, etc.) to improve both safety and performance.

For the drafting of EN 17975: 2025. Maintenance. Control of energy and fluid risks in maintenance activities, the standardization committee has taken into account the implementation of the French standard NF X60-400 and the combined experience of companies and organization, as well as technical, organizational and human risk factors. The standard is also inspired by international approaches such as Lock Out Tag Out (Lo-To), or Lock Out - Tag Out - Try Out (Lo-To-To), as well as best practice guides from around the world.

Among the operational measures proposed by the standard are the identification of energy sources, the choice of safety procedures, the principle of risk analysis, the location of locking devices and the introduction of "padlocks". To these should be added skills, training and qualifications. It offers specific advice on piping and mechanics and includes a flow chart and sample reference sheets for identifying hazardous energy sources in equipment, etc.

Risk analysis is an essential part of the safety process.

This analysis requires several skills, so it is often performed by several people (production, maintenance, operators or technicians):

• Knowledge of the energy and fluids associated with the equipment and its environment.
• Knowledge of energy and fluids related to the operation and process.
• Knowledge of work-related energies and fluids (e.g. welding).
  
  

It is recommended that the company establish a training and authorization system to ensure that all employees have the necessary skills and qualifications. The person who has an overview of all energies is generally the one who has the competencies to perform the risk analysis, not necessarily an expert in all energies.

Five safety categories or processes are described in the standard:

• Reinforced insulation.
• Simple isolation, with possible additional compensatory measures.
• Neutralization by means of a control system.
• Machine safety management during operation (e.g. during the test or diagnostic phase).
• Interlocking and signaling.
  
  

The CEN standard is voluntary.

The standard explains the links between the field of energy and fluids and other company processes: maintenance, production, safety, design, etc.

It also sheds light on the problem of the "gray zone", which is mainly the organizational ambiguity of maintenance operations performed by production.

Recurring operations can be handled by standard procedures. For non-recurring operations, the appendix of the standard proposes generic procedures that provide a framework for safety-related milestones, supported by operational aids (updated plans, Lo-To sheets listing the energies present and associated lockout devices, visual management, lockout managers, etc.).

The HOT LoToTo approach improves the efficiency and safety of maintenance operations by combining human, organizational and technical levers.

There is no magic solution. The subject is complex and each company has a different context, culture, facilities, process, organization and maturity... It is essential to start with a complete HOT LoToTo diagnostic to guide the right priorities and tailor the approach to the company.

Our diagnostic methodology also includes change readiness to facilitate the implementation of highly operational recommendations and support.

Technical: compliance/safety/maintainability/record keeping diagnostics, SOPs, Lo-To sheets, visual management of energy cut-off points, etc., the application of which for each piece of equipment also contributes to change behavior.

Organizational: traceability document templates, general procedure for ensuring energy and fluid safety, specification assistance, guidelines for energy and fluid lists and thresholds to be taken into account.

All that remains to be addressed is the main issue that complements the technical and organizational aspects: the human factor? To achieve this, we offer a full range of training courses (for maintainers, operators, external contractors, management committees, prevention officers, etc.), as well as a project approach supported by change management and actions to promote a culture of safe behavior.

Safety is priceless, but it costs money. The balance between the cost of safety improvement and the gain in safety is complicated. If a comprehensive HOT LoToTo approach is applied, ultimately the impact on performance, such as OEE (Overall Equipment Effectiveness), can be minimized, or even generate a performance gain through the return generated by good maintenance practices. After measurement and analysis, the results are surprising: in the medium term, good maintenance increases safety and also improves OEE.

By working better, a win-win situation is achieved, whereas in the past safety was sometimes compromised in favor of rapid intervention. Optimizing the safety system (using LoTo sheets mapping energy sources, pre-prepared operating procedures, etc.) will minimize the additional time needed for repairs. The best way to avoid putting yourself at risk when troubleshooting is to prevent breakdowns from occurring by making installations more reliable and ensuring that they are "consignable" (maintainable) at the design stage or through upgrades.

On the other hand, the approach will lose effectiveness, or even regress over time, if it dispenses with:

• A global approach, adapted to the context.
• A project management approach with a change management component.
• Long-term thinking.
• Consideration of human and organizational factors.
• Integration into safety management.
• Linkage with business processes.

Let's take the example of an initiative undertaken by a food processing company:

The agri-food sector is complicated because it requires a lot of maintenance, with very short lead times due to the processing of perishable foods. Margins are low and production rates are high, with very high levels of facility commitment. Maintenance teams work on a wide range of energy sources, not only electrical, but also mechanical, fluid, temperature, pressure, chemical hazards (e.g. decontamination), etc. New facilities coexist with older ones, which were not designed for safe maintenance work. The high accident rate led this company to implement the Apave HOT LoToTo approach as part of a health and maintenance safety policy, while taking into account the impact on performance.

The impact was measured objectively (TRS and Residual Risk indicators) and showed that the approach allowed combining the two components of risk and performance. The introduction of LoTo sheets and valve identification, combined with the work on recurring operations with standard operating procedures, has accelerated the process of ensuring safety and made the work and risk analysis more reliable.