At the beginning of 2012, the industry took a significant step in the continuing transition of safety standards that are emerging to define functional safety requirements for industrial machines. But while a large community of machine builders is already certifying their machines to these newer standards, a significant group seems to be lagging behind.
Current safety practices
According to a Design News survey, companies are certifying machines using a range of functional safety standards. A large group is certifying its machines using the ISO 13849-1 standard (42.9 percent), while others are certifying for NFPA (34.1 percent), IEC 62061 (29.7 percent), and the now-withdrawn EN 954 (15.4 percent) standard. More than half of the respondents (51.6 percent) are utilizing industry-specific safety standards such as Industrial Robots EN ISO 10218.
John D'Silva, marketing manager of Safety Integrated for Siemens Industry, told us:
What is very interesting is that more than 40 percent of the respondents reported they are already using ISO 13849 to certify their machines. In the past with new safety standards, we often found a cycle with customers of six to 18 months to understand the new standards and start talking solutions. This says that more customers are educated about the new safety standards.
The clear trend in safety logic devices is usage of safety relays decreasing, and the use of controller-based safety systems rapidly increasing. (Source: Design News)
Tim Roback, manager of marketing of Safety Systems for Rockwell Automation, said in an interview:
On the question about the functional safety level used to certify machines, anyone who answered EN 954 has an opportunity to get aligned because that standard has been withdrawn. Those people would need to decide what standard would apply to them, and probably ISO13849 would be the first place to look. One thing that is interesting, encouraging, and that Rockwell would recommend is that if customers have industry-specific standards, also known as C Level standards, they should use them, and 53 percent are doing just that. Engineers should look for industry-specific standards if they have them.
Types of safety logic devices
When asked what types of safety logic devices are currently implemented on machines, safety relays was the most common response (59.3 percent), but both safety controllers including PLCs and/or standalone safety controllers (49.1 percent) and integrated Safety Control Systems (53.7 percent) were not far behind.
As far as the types of safety logic devices customers are implementing, while there is a fairly even balance between safety relays and integrated safety systems, Roback expects that use of separate safety controllers will continue to decline.
In the US, enforcement is always a problem. Buyers and end users have to be careful what they buy.
Another thing to keep in mind is that EN13849 is a European standard. The Europeans have a whole collection of pretty well thought out standards covering machine safety. Only problem is they don't meet US requirements. OSHA expects us to follow 29CFR1910.xx. OSHA also recognizes ANSI standards. In machine safety, that means NFPA 79 and the ANSI B11 series.
Another modern standard that is being harmonized with the European standards is ANSI/ISA 84 which grew out of the process control industry. It was developed to avoid another Bhopal disaster. ANSI/ISA 84 uses the concept of Safety Integrity Levels (SIL) which are assigned based upon a risk and hazard analysis process. It's interesting that the new automotive safety standard ISO26262 has the concept of Automotive SIL. The levels are A-D rather than 1-4, but the concept is the same.
I have a friend who works for a company that does a lot of business with companies in China, Tim. He has always said that you can get anything manufactured in China at the highest level of quality or complexity that you desire - as long as you are willing to pay for it. I am sure they would recognize those safety standards if their buyers made it a criteria and were willing to pay for it...and if it evolved into a global standard that was enforced then they would just about have to or wouldn't have any business.
@Nancy Golden: Your friend is right. Chinese products have a reputation for poor quality largely because, when U.S. companies go to China, they're looking for the cheapest parts they can find. Of course, the cheapest parts you can find are usually not the best; that's true in any country, including the U.S. You get what you pay for. There are some world-class, high-quality manufacturers in China, but all too often, U.S. and other Western companies would prefer to do business with the bottom-of-the-barrel suppliers.
Rob, Responsibility for safety is a complicated issue (especially if liability is a question) but certainly everyone shares in it. Companies deploying machines have to meet regulatory requirements (such as OSHA) and I'm sure both machine builders and automation vendors are responsible for certifying machines and components. Not sure exactly how enforcement works, but I'm sure it depends on locations and rules around the world. Big challenge for machine builders.
I thought OSHA was the main safety enforcement body in the US. When I worked at manufacturing companies in the 80s, that's who everyone worried about pleasing, especially during their very infrequent inspections. That infrequency continues to be a problem: how can they enforce safety standards without frequent enough monitoring?
Ann, OSHA is the safety regulator in the US. I don't think OSHA has the resources to do many inspections. When a company has a serious accident, then they look closely and levy fines, etc. Companies are also required to report all work related injuries and illnesses, hence the term "OSHA Reportable". There are guidelines for what types of injuries are reported. There are also specific metrics that companies are required to report:
Total recordable cases of injuries and illnesses Injury and illness cases with days away from work, job transfer, or restriction Injury and illness cases with days away from work Injury and illness cases with days of job transfer or restriction Other recordable injury and illness cases Total injury cases
The metrics are normalized to the rate per 200,000 hours worked. These metrics are compared with other companies in the same industry. If your company stands out from the others, it is likely you will be visited by OSHA.
So it sounds like OSHA no longer does regular inspections looking for unsafe practices, in other words, proactive instead of reactive inspection. I wonder what happened to the funding for proactive inspection.
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