Overview
ISO 13849-2:2012 - "Safety of machinery - Safety-related parts of control systems - Part 2: Validation" specifies how to validate the safety functions, categories and performance levels (PL) of safety-related parts of control systems (SRP/CS). It defines a validation process combining analysis and testing to confirm that SRP/CS designed in accordance with ISO 13849-1 meet the required safety characteristics under expected operational and environmental conditions.
Key topics and requirements
- Validation scope: Confirms specified safety functions, achieved category, and achieved performance level for SRP/CS.
- Validation principles: Validation shall demonstrate compliance with ISO 13849-1 requirements including control of systematic failures, software requirements (where applicable), and operator ergonomics. Validation should be performed by persons independent of the SRP/CS design.
- Validation plan: Must document specification references, operational/environmental test conditions, analyses and tests to be used, applicable test standards, and responsibilities.
- Analysis and testing: Validation can use a mix of analytical techniques (failure mode analysis, diagnostic evaluation) and functional testing. For Categories 2, 3 and 4, testing under fault conditions is required.
- Fault consideration: Use generic fault lists (Annexes A–D) and, where needed, create product-specific fault lists. Fault lists cover mechanical, pneumatic, hydraulic and electrical technologies and identify permitted fault exclusions.
- Performance metrics: Validation addresses quantitative elements such as MTTFd (mean time to dangerous failure), diagnostic coverage (DC), and common-cause failures (CCF) as part of PL and category verification.
- Documentation and records: Produce validation records and technical documentation demonstrating the validation steps and outcomes.
- Technology-specific tools: Informative annexes provide validation tools and guidance for mechanical, pneumatic, hydraulic and electrical systems; Annex E gives an example for fault behaviour and diagnostics.
Applications and users
ISO 13849-2:2012 is used by:
- Machine designers and OEMs validating SRP/CS during design and prior to machine commissioning.
- Functional safety engineers performing PL and category verification and preparing validation plans and records.
- Integrators and control-system developers who must demonstrate safe behavior under faults and environmental conditions.
- Test labs and certification bodies assessing compliance with ISO 13849 series.
- Maintenance and safety managers who require documented validation for change control and periodic revalidation.
Practical uses include validating emergency stop circuits, safety interlocks, guarded access control, and other safety functions across mechanical, pneumatic, hydraulic and electrical control technologies.
Related standards
- ISO 13849-1:2006 - General principles for design of SRP/CS (required for design inputs).
- ISO 12100:2010 - General principles for design; risk assessment and risk reduction.
- IEC 61508 - Relevant when assessing programmable electronic systems and software.