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Functional Safety Consulting

Functional safety, reliability and compliance for your Safety Instrumented System (SIS)

Most industrial processes today rely on functional safety, a framework of Safety Instrumented Systems (SIS), to prevent hazardous scenarios for people, environment and facilities. We deploy a range of tools to assess the overall functional safety of your Safety Instrumented System, using different methodologies to identify the hazards, determine the Safety Integrity Levels for your safety instrumented systems and to perform the SIL Verification as part of the SIS design.

DEKRA’s Functional Safety expertise includes all the phases included in the Safety Lifecycle, SIL Verification, Safety Requirements Specification (SRS), Functional Safety Assessment (FSA), etc.)

International standards such as IEC 61508 and IEC 61511 define functional safety requirements for electronic systems and industrial applications in an effort to ensure that organisations maintain robust protections for all their processes.

As any process can have a combination of equipment, DEKRA UK has the Functional Safety Management (FSM) declaration with a ‘Notified Body’, as mandated in IEC61508, IEC61511, IEC62061, and the CCPS red book. DEKRA’s FSM includes the project’s team and is reviewed and monitored by the official Notified Body to ensure projects follow the correct procedures.

As part of our functional safety consulting services, Functional Safety Assessments (FSA) are carried out to ensure that your SIS includes the required Safety Instrumented Functions (SIFs) and that these are effective and reliable and maintain the required Safety Integrity Levels (SILs) through all the Safety Lifecycle. Our experts are knowledgeable and experienced in evaluating systems based on relevant international standards and thrive on collaboration with your team to improve your organisation’s overall functional safety. DEKRA ensure that what is recorded is in full compliance with IEC61511.

Your Benefits

  • Experienced support for all activities involved in the Safety Lifecycle: analysis, implementation, and operation.
  • A fail-safe functional safety system.
  • Compliance with international standards IEC61511 and IEC61508.
  • In-depth knowledge of your SIS and the functional safety management.
  • The full FSA, in accordance with IEC61511, can be carried out virtually.

Our Approach

Our approach is guided by the knowledge that, while standards may be universal, each organisation is unique. With this in mind, we develop customised assessment procedures for our clients defining the scope of the assessment, the assessors, participants of the FSA team, the planning of the FSA and the information that will be generated as a result of the FSA activity, all in compliance with IEC61511 Part 1. According to this specially designed procedure:

  • The FSA team reviews the work carried out in all phases of the safety life cycle.
  • Each FSA stage relies upon a different set of input documentation and assessment items to determine the acceptability of the SIS. FSA will be performed with detailed checklists or other support tools designed for the use of the assessor.
  • The FSA is completed after all equipment is installed and the SIS operation is validated, but before the startup of the process equipment under protection and before any dangerous substance is allowed to be handled by the system in accordance with regulations (for example in the the UK, in the DSEAR regulations it is necessary to prove that the system works as specified before any dangerous substance is allowed into the system at all.. In addition, SIS functional defects found during the assessment must also be resolved, or adequately managed compensating measures put in place, prior to startup.
  • The results of the FSA will be available in a report with the recommendations made from a full review of the assessment.

Customized functional safety assessment process by DEKRA
Functional safety assessment of the Safety Instrumented Systems (SIS) including Cyber risk as per IEC61508 and IEC61511.

Our experts base their assessments on the guidelines provided by international standards such as IEC 61508/61511 to determine the required reliability of Safety Instrumented Functions (SIFs) and to ensure that SIFs are designed and operated correctly. These guidelines include the following:

To determine the SIL for each SIF, several semi quantitative methodologies can be used. A risk-based review of the protection systems using Layers Of Protection Analysis (LOPA) or a Risk Graph methodology is recommended. The SIL is determined based on the semi-quantitative estimation of the frequency of the initiating event, and the severity of the hazardous scenario, as well as the effective Independent Protection Layers (IPLs).

A SIL verification assessment is typically carried out after a SIL determination study to review if the design of the SIF achieves the safety requirements and the required SIL. During this phase, the technology and architecture are defined and it requires a calculation of the SIL.
The evaluation of a SIF involves the analysis of the reliability and the architecture of the SIS according to the standards.

Validation procedures should provide assurance that the safety requirements specifications of the SIS have been met and that any recommendations from earlier verification activities and reviews have been satisfactorily addressed.


  • We are independent, third party functional safety experts.
  • We have international experience helping companies comply with functional safety standards.
  • We are specialists in functional safety consulting and your trusted advisors.

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