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Understanding IEC 61511 and IEC 61508 Standards for the Process Industry

Understanding IEC 61511 and IEC 61508 Standards for the Process Industry

Estimated reading time:  6 minutes


Understanding IEC 61511 and IEC 61508 Standards for the Process Industry


Process Safety is defined as a disciplined framework for managing the integrity of operating systems and processes handling hazardous substances through application of design principles, engineering, and operating practices. It aids in the prevention and control of incidents that have the potential to release hazardous materials or energy. It is first introduced by OSHA and looks at all the processes involved in handling, using, storing, moving, or manufacturing highly hazardous chemicals (HHCs).

For many years, Process Safety has been a constant challenge to all stakeholders in the industry including plant owners, regulators and social communities. Process industries are becoming increasingly reliant upon complex safety systems to prevent harmful incidents. With the rising adoption of Safety Case Regime in numerous countries, including Singapore, organisations need to be able to produce a comprehensive report to meet increasing safety standards.

In response to that, TÜV Rheinland has various certifications that industry professionals can acquire to gain the relevant knowledge in process safety. Their certifications are based on international standards and European directives. For the process industry, this refers to the IEC 61511 and IEC 61508 standards.


Understanding IEC 61511 and IEC 61508 for the Process Industry

Functional Safety for Safety Instrumented Systems (SIS) is for functional safety aspects for the process, oil & gas, and chemical industries according to IEC 61511. For engineers, professionals and specialists involved in safety instrumented systems, it is important to have the fundamental knowledge of functional safety and the requirements of the functional safety standard IEC 61511 in reference to the IEC 61508 standard.



IEC 61511: Functional safety for the process industry

IEC 61511 defines requirements regarding the application and implementation of safety instrumented systems (SIS) in the process industry. It describes functional safety (FS) requirements in process plants via a life cycle approach, from concept, through design, installation, operation, maintenance and decommissioning. Understanding and properly applying these regulations is essential not only for compliance, but, more importantly, for protecting people, assets and the environment as well.

It is important when risk analysis determines that a SIS is required, the required risk reduction becomes the performance target for the SIS.  IEC 61511 establishes requirements for designing and managing SISs to achieve specified safety integrity levels (SIL), which are related to order of magnitude ranges of risk reduction. Performance verification of safety instrumented functions is demonstrated using calculation techniques to determine the probability of failure on demand and spurious trip rate and using key performance indicators for feedback from field operations.


IEC 61508 standard: Functional safety across industries

IEC 61508, the foundation for IEC 61511, was first introduced in 2000. The IEC 61508 standard is a generic functional safety standard which can be applied to any kind of safety system if the safety system has elements based on electrical, electronic or programmable electronic (E/E/PE) technology. This does not mean that the whole safety system needs to be based on E/E/PE technology. The safety system is allowed to have elements based on other technologies like mechanical, electro-mechanical or even pneumatic elements. The IEC 61508 is a complete standard and it addresses requirements for achieving functional safety in the systems it covers.


All in all, functional safety is an important fundamental concept applicable across all industry sectors. It is fundamental to the enabling of complex technology used for safety-related systems, based on the assurance that these systems are operated safely and with minimal risks. Several industries such as the oil and gas industry, rely heavily on functional safety to achieve safety for the equipment giving rise to the hazards.


TÜV Rheinland Functional Safety Engineer Safety Instrumented Systems (SIS) is a 4-day training course held from 6-9 April 2020 (Kuala Lumpur). This training focuses on functional safety aspects for process, oil & gas, petrochemical and chemical industries according to IEC 61508 / IEC 61511. This includes the complete safety lifecycle in the context of Safety Instrumented Systems (SIS) projects. We also include many fundamental topics that we know you need to understand, but are not covered in the standards. Practical exercises will be performed throughout the course based on real-life examples.

Unable to make it for the April Course? Contact us for other available dates. 


TÜV Rheinland Functional Safety Engineer Safety Instrumented Systems (SIS)


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