Best Practices

Machinery Control Systems One Global Safety Standard

By Derek Jones and Mike Miller

In 2016, two machinery control standards, EN ISO 13849 and IEC 62061, are scheduled to merge into one, ISO/IEC 17305. How much time is there to prepare for the merger? The adoption target allows 2 years of transition to 2018 (although the standards organizations may need additional time to finalize ISO/IEC 17305). Some original equipment manufacturers (OEMs), especially those located outside the European Union, may question the need and relevance of the merger. Understandably, many OEMs have a keen interest in confirming that the potential gains justify climbing what might appear to be another standards mountain. These gains, for example, may include capitalizing on advanced technologies and eliminating technical barriers in global trade.

OEMs should be optimistic, however. The merger that will create ISO/IEC 17305 signals the summit of challenges related to global machinery safety control standards. The basic methodology and essential requirements introduced in ISO 13849 and IEC 62061 should not require significant alterations. Unifying the two standards should simply combine the best achievements of each, simplifying and making a single, more user-friendly standard. It may also resolve some known issues and gray areas identified during the past 6 years of using the existing standards.

Having navigated the previous safety-standard migration will be a useful preparation to adopting ISO/IEC 17305. With the EN 954-1 to EN ISO 13849-1 experience in hand, OEMs will find the next transition to be a more manageable leap. They can leverage any lessons learned from continued use of the existing ISO and IEC standards to streamline their transition.

OEMs moving from the simple safety categorization of EN 954-1 to the significantly more complex ISO 13849 or IEC 62061 standards did not greet the transition with universal acceptance. At the same time, there was a consensus that increasingly sophisticated safety automation technology clearly required parallel and robust enhancements to safety standards.

Growing worldwide adoption of the ISO and IEC standards that superseded EN 954-1 at the end of 2011 is validating that prediction. The new generation of complex electronic and programmable safety automation technology exceeds the ability of the relatively simple and semi prescriptive EN 954-1, which essentially provides guidance on control system structure. The newer, more comprehensive functional safety standards enable confident use of new technology by requiring designers to assess all aspects relevant to the long-term reliability of safety components.

More rigorous documentation requirements combined with a quantitative calculation for assessing reliability increases the complexity. But those types of trade ups resulted in a methodical approach that is helping OEMs develop safer machinery—using standards that allow use of contemporary technology and can be used to show compliance across worldwide markets—with more predictable performance, greater reliability and availability, and improved return on investment.

All Indicators "Go"

Justifying a wait-and-see position on ISO/IEC 17305 is becoming harder to do. The most obvious indicator that a unified standard will emerge is the approaching end of development activity on ISO 13849 and IEC 62061 as separate standards. The preliminary planning process has already started on ISO/IEC 17305, and drafting will begin in 2013.

Other leading indicators for a single global safety standard include:

• ISO and IEC are relevant to U.S. machinery and equipment building. There is one particularly compelling, mainstream precedent on this topic. ISO 12100 is a basic principle machinery safety standard providing a best practice framework to identify risk and eliminate hazards during the design stage. It demonstrates forcefully that what have been perceived as European standards are truly international. Not only is ISO 12100 a consensus standard in the U.S., some of its major influences are provided by U.S. OEMs, machinery users and safety device manufacturers.
• Many national standards already have provisions in common with the equivalent ISO and IEC versions. An increasing number of regions around the world are adopting ISO and IEC standards as national standards. Consider a U.S. manufacturer selling to China and the European Union, or a China-based company exporting to the U.S. The different standards that come into play (e.g., UL, ANSI, EN, GB) might appear to be silo-creating guidelines that complicate life for global exporters and importers alike. But current standards are often similar, sometimes up to 90% similar from one to the next. What are the most frequent commonalities? Predictably, they share significant elements with ISO and IEC standards.
• There is no "going back" based on complexity and data demands. Today's safety function is often not a simple case of switching off the power. Safety-capable logic that enables intelligent safety operations is only one example of the flexible, advanced functionality requiring greater provisions against mistakes and faults. The increased complexity and requirements for reliability calculations created some understandable frustrations, not the least of which has been a lack of data. But in many cases this issue has now been resolved. There is no benefit of delaying, hoping that the complexity will disappear. It will not. Understanding the existing ISO 13849 and IEC 62061 will certainly allow for easier transition to ISO/IEC 17305.

The bottom line: Global trade means global standards. The ISO/IEC 17305 is scheduled to be published by 2016. The intervening time before then is best spent becoming familiar with its ISO 13849 and IEC 62061 foundations. Organizations familiar with the two standards should be comfortable with what is in the unified standard.
The merger process will not introduce any significantly different requirements. It will clarify and simplify. Industry is simply steering a course toward an optimized global reaching standard that will help OEMs build safer, higher-performing and internationally competitive machinery, while helping to take cost out of the multinational safety-compliance process.

Derek Jones is Rockwell Automation's business development manager for safety, and Mike Miller is the firm's FS TÜV expert, global safety market development. For more information, visit the Rockwell Automation Safety Resource Center at http://discover.rockwellautomation.com/safety and the Rockwell Automation Guardman Blog at www.guardmanblog.com.