Free quick guide to SIL Certification

On this page, you will find the key concepts of Functional Safety and the benefits of SIL Certification with BYHON.

1. What is Functional Safety and what is its purpose?

Functional safety is a discipline focused on ensuring that systems and devices operate safely, even in the presence of faults or malfunctions. It is a fundamental part of the overall safety of a system, concentrating on the proper functioning of safety functions designed to prevent or mitigate hazardous situations.

 

Definition of Functional Safety

According to the IEC 61508 standard, functional safety is defined as “the part of the overall safety that depends on a system or subsystem operating correctly in response to its inputs.” In other words, it is the ability of a system to detect hazardous conditions and automatically activate the necessary measures to prevent harm to people, the environment, or physical assets.

 

Objectives of Functional Safety

The main objectives of functional safety include:

• Protecting People: minimizing the risks of accidents that could cause injuries or fatalities.
• Protecting the Environment: preventing environmental damage caused by system failures or malfunctions.
• Protecting Physical Assets: safeguarding infrastructure and equipment from damage caused by hazardous events.
• Ensuring Operational Continuity: guaranteeing that critical systems continue to operate safely even in the event of a failure

 

Importance of Functional Safety

With the increasing complexity of industrial systems and automation, functional safety has become a critical element for ensuring protection in high-risk industries, such as:

• Process Industry: preventing explosions, fires, and hazardous substance leaks
• Automotive: ensuring the safety of assisted and autonomous driving systems
• Energy: protecting power plants and energy infrastructure
• Railway: ensuring the safety of signaling and railway traffic control systems
• Industrial Machinery: preventing workplace accidents caused by machinery failures

 

2. Standards governing Functional Safety and Analysis methods

Functional safety is regulated by a series of international standards that establish requirements for the design, implementation, and maintenance of safe systems. Among these, IEC 61508 is the primary reference standard.

 

The IEC 61508 Standard

IEC 61508 is an international standard that defines requirements to ensure the functional safety of electrical, electronic, and programmable electronic systems (E/E/PE). It is considered the “mother standard” of functional safety, as it provides a general framework applicable to various industrial sectors.

 

Structure of IEC 61508

The standard is divided into seven main parts:

• Part 1: General requirements for functional safety
• Part 2: Specific requirements for hardware systems
• Part 3: Specific requirements for software systems
• Part 4: Definitions and abbreviations
• Part 5: Methods for determining Safety Integrity Levels (SIL)
• Part 6: Guidelines for applying Parts 2 and 3
• Part 7: Overview of techniques and measures for functional safety

 

Key Principles of IEC 61508

The standard is based on several key principles::

• Safety Lifecycle Management: functional safety must be considered at all stages of a system’s lifecycle, from initial design to decommissioning.
• Risk Reduction: risks must be reduced to an acceptable level, following the ALARP principle (As Low As Reasonably Practicable)
• Safety Integrity Levels (SIL): the standard defines four Safety Integrity Levels (SIL 1-4), representing the degree of risk reduction required for a safety function

 

Standards Related to IEC 61508

IEC 61508 serves as the foundation for many industry-specific standards, including:

• IEC 61511: Functional safety for the process industry
• ISO 26262: Functional safety for the automotive sector
• EN 50126/8/9: Functional safety for the railway sector
• IEC 62061: Functional safety for industrial machinery

 

Safety Functions and Safety Integrity Level (SIL)

Safety functions are specific control functions implemented by a safety system to achieve or maintain a safe state for the EUC (Equipment Under Control) in relation to a specific hazardous event. The Safety Integrity Level (SIL) is a discrete level (from 1 to 4) that represents the degree of risk reduction required for a safety function. SIL 4 represents the highest level of safety integrity, while SIL 1 represents the lowest level.

 

Risk Reduction Strategy and Analysis Methodologies

Functional safety relies on a risk reduction strategy that follows the ALARP principle (As Low As Reasonably Practicable), meaning that risks must be reduced as much as reasonably possible. Risk analysis methodologies include:

• What-if analysis: brainstorming to analyze the effects of undesirable events
• Hazard and Operability analysis (HazOp): identifying deviations from normal operations
• Fault Tree Analysis (FTA): analyzing causes leading to a hazardous event
• Event Tree Analysis (ETA): analyzing the consequences of malfunction

 

SIL Allocation and Methodologies

SIL allocation depends on risk analysis and is not purely mathematical but requires an experienced team, including process specialists, technicians, maintenance personnel, and management. Two common methodologies for SIL allocation are:

• Risk Graph: uses parameters such as consequences, frequency, avoidability, and probability
• LOPA (Layer of Protection Analysis): analyzes independent protection layers

 

Safety Integrity Levels (SIL)

IEC 61508 defines four Safety Integrity Levels (SIL), representing the degree of risk reduction required for a safety function:

• SIL 1: risk reduction from 10 to 100 times
• SIL 2: risk reduction from 100 to 1,000 times
• SIL 3: risk reduction from 1,000 to 10,000 times
• SIL 4: risk reduction from 10,000 to 100,000 times

 
The choice of SIL level depends on risk analysis and the severity of the consequences of a potential failure.
 

3. Why certify a device for SIL?

SIL (Safety Integrity Level) certification is a process that ensures a device or system meets the safety requirements defined by the IEC 61508 standard.
Certification is essential to demonstrate that a device can reliably perform its safety functions in compliance with international standards.

 

Benefits of SIL Certification

• Regulatory compliance: SIL certification is often a mandatory requirement in many regulated industrial sectors
• Risk reduction: ensures that the device contributes to reducing risks to an acceptable level, protecting people, the environment, and physical assets
• Enhanced corporate reputation: a SIL-certified device is synonymous with quality and safety, increasing customer and partner trust
• Access to international markets: SIL certification is globally recognized, facilitating access to new markets and business opportunities
• Cost optimization: SIL certification can reduce costs associated with incidents, product recalls, and operational disruptions

 

4. How BYHON certifies SIL devices

BYHON is an accredited body specializing in SIL certification according to the IEC 61508 standard. The certification process offered by BYHON consists of several phases:
 

1. Preliminary Analysis:

• Identification of the device’s safety functions
• Risk assessment associated with the system

 

2. Design and Verification:

• Review of hardware and software design to ensure compliance with IEC 61508 requirements
• Analysis of failure modes (FMEA, FTA, etc.)

 

3. Testing and Validation:

• Execution of functional and reliability tests to verify device performance
• Simulation of failure scenarios to evaluate system response

 

4. Documentation and certification:

• Preparation of the technical documentation required by the standard
• Issuance of the SIL certificate, certifying device compliance

 

5. Post-Certification support:

• Continuous assistance to maintain compliance throughout the product lifecycle

 

Why Choose BYHON for SIL Certification?

• Proven expertise: BYHON is an organization of HON S.r.l. and part of the TÜV Rheinland group, a global leader in certification and industrial safety
• Technical competence: BYHON’s team consists of highly qualified experts with in-depth knowledge of the IEC 61508 standard and its applications across various industrial sectors
• Human approach: BYHON offers customized solutions for the specific needs of each client, providing comprehensive support throughout the certification process
• Innovation and technology: BYHON uses cutting-edge tools and methodologies to ensure a fast, precise, and effective certification process
• International recognition: lSIL certifications issued by BYHON are globally recognized, giving clients a competitive advantage in international markets

 

Make the right choice. Obtain an excellence certification quickly.

Functional safety is a crucial element for ensuring the protection of people, the environment, and physical assets in high-risk industrial sectors. The IEC 61508 standard is the primary reference for the design and certification of safe devices and systems.
With its experience, expertise, and tailored approach, BYHON is the ideal partner for companies seeking SIL certification for their devices. Choosing BYHON means selecting a globally recognized leader capable of ensuring a rigorous and transparent certification process.