17 May 2023
Updated ISO Standard 13849-1 for Machinery Control System Safety
A new version of the ISO 13849 standard for machinery control system safety has been released, replacing the previous version from 2015. ISO 13849-1 provides safety requirements and guidance on the principles for the design and integration of safety-related parts of control systems (SRP/CS), including the design of software and specific requirements for SRP/CS using programmable electronic systems.
The new version of the standard has been rearranged so it better represents the design and development process for control systems.
Other changes include:
- Addition of a focus on risk assessment recommendations. For example, Figure 2 of Clause 4 is an enhanced version of Figure 1 in the current version - breaking out the ‘three-step process’ of risk reduction. However, the overall process and the relationship with ISO 12100 is unchanged. The new Figure 3 is also an enhanced version of the current Figure 2, which describes the contribution to risk reduction.
- New Clause 7 on software safety requirements which includes an explanation of the differences between 'limited variability' and 'full variability' and provides guidance in deciding between them.
- Clause G.5 of Annex G requires a functional safety plan to be drawn up and documented for each SRP/CS design project, including the identification of relevant activities and roles, resources, and a validation plan.
- New Annex L covering electromagnetic interference (EMI) immunity. (Some EMC experts have expressed concern about this new section. This is mainly because one of the 'routes' described in this annex (Route C) allows for a claim of satisfying EMI without increased immunity testing.) It provides a scoring methodology (table L.1) that can be used to assess equipment that integrates electronics by considering various measures to achieve immunity.
- Annex M now contains additional information for safety requirements specification.
- Annex N introduces the concept of fault-avoiding measures for the design of safety related software to help users of the standard apply the requirements of Clause 7 on software safety requirements.
- Annex O now deals with safety-related values of components or parts of the control systems. This is extracted from a data library format created by the German machinery manufacturers association (VDMA). It has been around for some years and is used in applications like SISTEMA and PAScal to help with the calculations for hardware reliability.
Once listed in the Official Journal (OJEU) as a harmonised standard, the new version has a presumption of conformity, meaning that following it will ensure products are in line with corresponding EU rules. There may be a transition period of up to three years before the superseded version is withdrawn from the OJ, ending its presumption of conformity. The new version will also become a designated standard in the UK. The standard is now also published as EN ISO 13849-1, and as BS EN ISO 13849-1.
Stewart Robinson, Functional Safety Senior Product Specialist and Trainer said:
“The updated ISO 13849 standard for machinery control system safety is essential for ensuring safety in the manufacturing industry. With the new version providing greater rigor and guidance on risk assessment, the implementation of the standard will ultimately lead to safer machinery control systems, reducing the risk of accidents and injuries in the workplace.”
Learn more about how TÜV SÜD can improve your functional safety of industrial machinery and ISO 13849-1.
Find out more about ISO 13849-1:2023 on the ISO website
