Direct types of energy in mechanical engineering such as electrical energy, gas, hydraulics, pneumatics or through reactions of chemical substances are known. However, there is also indirect or secondary energy - for example, when a flywheel with a motor drive continues to rotate with rotational energy after it has been switched off, when parts tensioned with spring force hold kinetic energy or when there is residual pressure in a container. The five safety rules from VDE 0100 electrical engineering ensure that electrical energy does not cause any damage. They are: disconnect (switch off the power supply), secure against reconnection, ensure that there is no voltage, earth and short-circuit and cover or isolate live parts. All other types of energy, direct and indirect, are not taken into account. This is exactly what LOTO (lockout, tagout) can do - it safely switches off and checks all existing energy.

In the USA, the Occupational Safety and Health Administration (OSHA) regulates the relevant criteria and minimum requirements. There, LOTO is used for recurring work on machines and systems, such as maintenance, servicing and cleaning. The LOTO procedure comprises the following steps: The affected switch is flipped, thus switching off the power, the switch is secured with a lock, and the name, date and reason for the switch-off are then written on a label. Then the absence of voltage is checked with a measuring device to ensure that the switch is not broken. Another name for the procedure is LTV - logout, tagout, verify. This ensures, for example, that there is no residual pressure, that the hydraulics have stopped and that no acids or alkalis have remained in the lines.

Employer responsibility

The need for LOTO also exists in Europe, even if the legislator does not provide for such a regulation. Occupational safety during maintenance or cleaning work is regulated by the European Directive 2009/104/EC on the minimum safety and health requirements for the use of work equipment by workers at work. Employers are responsible for providing their employees with only safe work equipment. Work equipment includes everything that employees need to carry out their work. The directive covers not only normal use, but also troubleshooting, maintenance, servicing and cleaning. This implies LOTO, even if the term is not used.

More and more companies are introducing such a system in Germany. Some companies with subsidiaries in the USA are adopting it because of the American influence, while others are increasing their focus on safety. This is because the majority of serious accidents in industry still occur not during normal operation, but during maintenance, servicing or cleaning, because there is still residual energy in the system that has not been switched off. The problem: while electrical energy can always be secured via the main switch, other energies cannot always be shut off without further ado, even if machine builders are required to do so during design and risk assessment. Positional energy in particular is often neglected in machines with lifting components and vertical movements. There is then a lack of options for blocking the kinetic energy and preventing parts from falling.

In a LOTO program, responsibilities and processes are defined, procedures for separating energies are described and the necessary tools are agreed upon. This ensures that everyone involved is on board and everyone, regardless of their role, knows what is at stake. Fundamental considerations need to be made: Who is responsible and writes the procedures, are the necessary qualifications available? Special processes such as cross-shift maintenance must be taken into account and procedures defined if external companies are involved, for example. This is where personal identification locks and machine identification locks come into play, for example. The LOTO program also documents who is trained, how and when, and at what intervals the procedures are reviewed. These procedures must be easy to read, not cumbersome, easily accessible and must not cause additional work for the employee.

The implementation of LOTO

The first question when implementing a LOTO program is the LOTO capability of the machines and systems in the company. Can all energies be disconnected? Will other machines that also need to be secured be affected? The analysis of the energy types and safety areas of the systems is written in a procedure. Machines and systems are subdivided into areas that should be able to be isolated separately. A risk assessment is then carried out on the types of energy present in the area. The options for switching off the energy and auxiliary equipment are defined.

A LOTO procedure contains a checklist for specific machines with layouts including shut-off points, energy types and information on how to shut down and how to check. The sequence of the shutdown is determined, as well as the steps for restarting the machine. Minimum information and other options are also provided: Permission slips from the health and safety officer or reference to residual hazards and measures to mitigate them. The procedures are reviewed and the employees are then trained. This employee training is essential. Employees must know where the switch-off points are located and how and with what tools they can operate them. This is because not every switch has a lock, and handwheels and ball valves are secured with an aid. It must also be ensured that the LOTO boards with the locks are complete. LOTO implementation requires practice, as errors can occur during use. The procedures must subsequently be checked regularly or after modifications to ensure that the representation and actual status match. As a "CLTTE certified LOTO expert", the Bremen-based safety expert Ce-Con implements and audits LOTO programs and checks whether they are complete and being implemented in the company. A LOTO program requires a holistic view of all processes and careful training of employees. Only then will it be sustainable and successful.

Jörg Handwerk, Managing Director at CE-Con