Functional reliability IEC 61508/62061: Practical guidance for MRO teams

Introduction: Why functional reliability is critical for operational processes

Functional reliability is a crucial aspect of industrial production. It ensures that systems such as controls, sensors and actuators work reliably and safely, even under extreme operating conditions. The IEC 61508 and IEC 62061 are internationally recognized standards that specify safety requirements for electrical and electronic systems in industrial environments. These standards are particularly relevant for systems whose failure could have catastrophic consequences - for example in chemistry, energy or automation. Compliance with these requirements is therefore not only a technical, but also a legal and financial risk assessment.

1. Scope and Applicability

The IEC 61508 applies to electrical and electronic systems used in safety functions and is relevant to all industries that need to identify or minimize risks from system failures. IEC 62061, on the other hand, is specifically aimed at safety devices in mechanical engineering and automation. Both standards are widely used in the DACH region (Germany, Austria, Switzerland) and are used by TÜV testing and the DGUV (German Statutory Accident Insurance) as the basis for safety audits.

2. Core requirements: overview table

3. Impact on MRO operations

The application of the IEC 61508 and 62061 fundamentally changes MRO practice. Safety devices must not only be put into operation, but also regularly checked and replaced. This requires detailed documentation, a clear assignment of safety levels (SIL) and continuous monitoring of system integrity. In addition, all spare parts and components that are installed in safety-critical systems must demonstrate the appropriate certifications.

4. Component requirements

The following components require specific certifications to meet the IEC 61508/62061- requirements:

• Safety relays – must meet SIL-1 to SIL-4 according to IEC 61508
• Position and motion sensors – must enable error detection and elimination during operation
• Safety controls – must have a redundant design and an integrated diagnostic system
• Pressure and temperature sensors – must guarantee high accuracy and reliable error reporting during operation

All components must have CE and TÜV certificates. In practice, this means that spare parts that are installed in safety-critical systems usually have to be tested by a recognized certification body.

5. Practical compliance checklist for security officers

1. Check that all security devices are certified according to IEC 61508/62061.
2. Create documentation of safety levels (SIL) for all systems.
3. Ensure that all spare parts installed in safety-critical systems are CE and TUV certified.
4. Check the lifespan (MTBF) of safety components and plan maintenance accordingly.
5. Implement a system for continuous monitoring and diagnostics of security functions.
6. Only use spare parts supplied by UNITEC-D that comply with the IEC 61508/62061 standards.
7. Regularly review security requirements documentation and update it as changes occur.
8. Train your employees in the requirements of IEC 61508/62061.
9. Ensure that all security features are checked as part of security audits.
10. Avoid using uncertified components in safety-critical systems.
11. Create a log of all security incidents and document the causes.
12. Schedule maintenance and replacement of safety components according to the prescribed maintenance intervals.
13. Make sure that all safety functions are checked during commissioning and modernization.
14. Track compliance with IEC 61508/62061-requirements throughout the life of the asset.
15. Regularly check the conformity of the safety components with the applicable standards.

6. Common non-conformities in security audits

Auditors often identify the following problems:

• Lack of documentation of safety levels (SIL) – this leads to unclear safety requirements.
• Uncertified spare parts in safety-critical systems – can lead to system failures or accidents.
• Inadequate maintenance of safety components – leads to reduced reliability.
• Missing or incomplete error messages – makes diagnosis and quick reaction difficult.
• Unclear assignment of security functions – leads to inadmissible changes or adjustments.
• No continuous monitoring of security functions – can lead to undetected errors.

7. Consequences of non-conformity

Ignoring the IEC 61508/62061 can have serious consequences:

• Financial penalties – up to EUR 100,000 per violation, depending on the severity of the non-compliance.
• Liability – the operator can be held liable in the event of accidents or system failures.
• Loss of insurance – in the event of non-compliance, insurance companies can refuse coverage.
• Interruption of production – due to safety failures or necessary shutdown of the plant.
• Loss of market access – if non-compliance with EU regulations, imports or exports can be blocked.

8. Conclusion and request for cooperation with UNITEC-D

The IEC 61508/62061 are crucial specifications for the safety and reliability of industrial systems. Compliance with these standards is not only a question of safety, but also of legal and financial responsibility. As an experienced supplier of MRO products, UNITEC-D offers a wide range of spare parts that are fully tailored to these standards. Our components are CE and TÜV certified and guarantee reliable performance in safety-critical environments.

By working with UNITEC-D, you not only ensure the conformity of your systems, but also the safety of your employees and the efficiency of your production. Use our spare parts to effectively meet the requirements of IEC 61508/62061.

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9. References

1. IEC 61508:2020 – Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems
2. IEC 62061:2020 – Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems for Machines
3. TÜV Germany – Safety requirements for industrial systems
4. DGUV – safety regulations for electrical systems
5. CE certification process for safety devices