Understanding ISO 13849: The Foundation of Functional Safety in the Machinery Sector
The Essential Guide to Requirements Management and Traceability
Understanding ISO 13849: The Foundation of Functional Safety in the Machinery Sector
In industrial machinery, as in many industries, functional safety is a critical part of machinery design – ensuring the protection of operators, equipment (and surrounding environments) from hazardous situations. To help maintain functional safety in industrial manufacturing, most machine builders use ISO 13849, a globally recognized standard that sets requirements for designing and validating the safety-related parts of machinery control systems.
In this article, we’ll look at the importance of ISO 13849, key components, and how it shapes functional safety in the machinery sector.
What Is ISO 13849?
ISO 13849, “Safety of machinery – Safety-related parts of control systems,” is the international standard that sets out the principles for designing and assessing the safety-related parts of control systems (SRP/CS). SRP/CS are the parts of a machine’s control system that perform safety functions, from the input device through the logic to the output: for example, an emergency stop circuit, a guard interlock, or a light curtain and the logic that responds to it.
- ISO 13849-1 (General principles for design): How to specify, design, and verify safety functions and their Performance Levels. The current edition was published in 2023.
- ISO 13849-2 (Validation): How to validate that safety functions meet their requirements, including fault lists and fault exclusions for common technologies.
By following ISO 13849, manufacturers can reduce the likelihood of machinery-related accidents and improve overall safety compliance.
ISO 13849 or IEC 62061?
IEC 62061 is the other machinery functional safety standard. It rates safety functions by Safety Integrity Level (SIL 1 to 3) rather than Performance Level, and its 2021 edition extended it beyond electrical control systems. Both standards are harmonized in the EU and either can be used to demonstrate conformity, so teams usually choose based on the technologies involved and their existing practice. Both build on the generic functional safety standard IEC 61508.
Why Is ISO 13849 Essential in the Machinery Industry?
Is it mandatory? Not in itself, but it is the most common way to show that a machine’s control systems are safe. In the European Union, ISO 13849-1 is harmonized under machinery law, so meeting it gives a presumption of conformity with relevant essential health and safety requirements. Those requirements move from the Machinery Directive (2006/42/EC) to the Machinery Regulation (EU) 2023/1230 on 20 January 2027. Other standards also build on it: ISO 10218 for industrial robots, for example, states its safety function requirements as Performance Levels.
The standard’s widespread adoption reflects its importance across the machinery industry. In an informal ISO/TC stakeholder survey, more than 89% of machine builders and more than 90% of component manufacturers and service providers reported using ISO 13849 as their functional safety standard.
However, the machinery sector operates in environments where equipment malfunctions can lead to severe injuries, fatalities, and property damage. Functional safety, as applied through ISO 13849, helps mitigate these risks by emphasizing:
- Reducing Risk: Identifying potential hazards and designing systems to minimize them.
- Reliability: Ensuring that safety-related control systems perform their intended functions under all reasonably foreseeable conditions, including when components fail.
Compliance with ISO 13849 can also help teams avoid legal and financial repercussions if something does go wrong.
ISO 13849 bridges the gap between innovation and safety, enabling manufacturers to integrate cutting-edge technology without compromising operator protection.
Key Info About ISO 13849
ISO 13849 revolves around several core principles.
- Performance Level (PL) – Performance Level expresses how reliably a safety function performs under foreseeable conditions, from PL a (lowest) to PL e (highest), based on the average probability of a dangerous failure per hour (PFHd). The PL that a safety function achieves depends on:
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- Its architecture, expressed as a Category (B, 1, 2, 3, or 4).
- Diagnostic coverage (DC).
- Mean time to dangerous failure (MTTFd).
- Common cause failure (CCF) protection.
- Measures against systematic failures, including in safety-related software.
- Risk Assessment and Reduction – Risk assessment itself follows ISO 12100. ISO 13849-1 then determines the required Performance Level (PLr) for each safety function, typically with a risk graph based on the severity of injury, the frequency and duration of exposure, and the possibility of avoiding the hazard.
- Validation – First, the PL each safety function achieves is verified against its PLr. Validation then confirms that the implemented safety functions meet the safety requirements specification and operate correctly under foreseeable conditions. ISO 13849-2 provides specific procedures for this step.
- Diagnostics and Redundancy – Built-in diagnostics and redundant systems enhance reliability, preventing failures from leading to unsafe conditions.
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Implementing ISO 13849 in Functional Safety Design
Successfully implementing ISO 13849 needs a structured approach:
- Risk Assessment: Identify hazards across the machine’s life cycle and operating modes, then estimate and evaluate the risks (ISO 12100).
- Determine Safety Requirements: Write a safety requirements specification for each safety function, including its required Performance Level (PLr).
- Design Safety Systems: Develop control systems with redundancy, diagnostic coverage, and robust design principles.
- Verify the Achieved PL: Calculate the PL each safety function achieves and confirm it meets the PLr.
- Validation: Validate each safety function against its specification using the procedures in ISO 13849-2, and keep the evidence in the technical documentation.
Benefits of Choosing to Comply With ISO 13849
Adhering to ISO 13849 delivers a lot of advantages for machinery manufacturers and operators:
- Enhanced Safety: Reduces the risk of accidents and improves operator confidence.
- Regulatory Compliance: In the EU, conformity with this harmonized standard gives a presumption of conformity with the relevant machinery requirements, easing market entry and reducing liability.
- Cost Efficiency: Minimizes downtime and damage from malfunctions.
- Reputation Management: Demonstrates a commitment to safety and reliability, boosting brand credibility.
Common Challenges With ISO 13849 and How to Overcome Them
Implementing ISO 13849 can be challenging, especially for manufacturers unfamiliar with its requirements. Common obstacles include:
- Complexity in Risk Assessment: Accurately determining Performance Levels requires expertise.
- Integration With Legacy Systems: Retrofitting older machines can be resource intensive.
- Validation Procedures: Comprehensive testing can be time-consuming.
- Keeping Documentation Current: Every design change can affect a safety function’s PL and its validation evidence, and keeping that chain up to date by hand is error-prone.
Overcoming These Challenges
- Engage Experts: Don’t go it alone, collaborate with functional safety specialists.
- Use Certified Components: Choose components with published reliability data (such as MTTFd or B10d values) or PL ratings, but remember that the PL of each safety function must still be verified at the system level.
- Invest in Training: Help your team succeed. Equip them with the knowledge to apply the standard effectively.
- Maintain Traceability: Link each hazard to its safety function, its PLr, the design that implements it, and its verification and validation results so the impact of a change is visible immediately.
Strengthen Machinery Safety With ISO 13849
ISO 13849 serves as a cornerstone of functional safety in the machinery sector. By following its guidelines, manufacturers can design systems that not only meet regulatory expectations but also provide robust protection against operational risks. In an industry where safety is paramount, ISO 13849 ensures that innovation and reliability go hand in hand.
Meeting ISO 13849 requirements calls for clear safety requirements, traceability, and documented verification and validation. Jama Connect® helps engineering teams manage these activities, assess the impact of changes, and maintain the evidence needed to support functional safety and compliance.
This article was authored by Patrick Garman and published on October 22, 2026.
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