Industrial safety first
Damages and loss caused by safety system failures push manufacturers to speed up technical improvements for safety implementations. By integrating safety and control functions, new safety control solutions reduce potential damage and hazards and improve productivity and competitiveness of the corporation.
How important is machine safety? According to a study from the U.S. National Institute for Occupational Safety and Health (NIOSH), machines are the second biggest killer after vehicles, which is the biggest. Recent accidents, such as a high-speed train derailment, escalator failure, subway train crash, and others, have drawn public attention. In October 2011, the Rockwell Automation “Decode safety automation” seminar and First TÜV Rheinland Greater China International Functional Safety Symposium were held in Shanghai one after another, with many discussions of safety trends.
Safety integration boosts productivity
Traditional machine safety system is independent of the automatic control system, and usually the equipment cannot be maintained and repaired until it is fully shut down, which costs a lot of time and money. Safety-related casualties and other accidents include many direct and indirect potential costs.
Direct costs include:
- Medical bills
- Insurance premiums
- Production loss caused by breakdown
- Damage of equipment
- Recruitment and training of temporaries
And indirect costs include:
- Additional workload of constructive acceleration
- Reputation impairment
- Low morale and tension between labor and plant managers
Potential cost of safety accidents
It is not hard to see that there are many kinds of direct and indirect substantial costs caused by safety accidents. George Schuster, senior industry consultant of Rockwell Automation, noted the following:
Suppose the cost of a breakdown is $10,000 per minute, there are 3,000 breakdowns in one year (8 breakdowns per day), and each breakdown lasts 2 minutes. The breakdown loss could be as high as $60 million. So if safety measures are aimed only at compliance, the cost of maintenance is very high, even though the short-term machine expense is less.
More manufacturers are considering integration of safety technologies into standard automation products, such as programmable automatic controllers, programmable safety relays, transducers, and servo drivers, to reduce the loss due to system failures.
As industry technologies and standards advance, safety integration designs provide flexibility and cost efficiency. Sharing some system components between standard automation and the safety system reduces hardware cost; using one software suite reduces training and support cost; operators and maintenance personnel can diagnose the problem and service equipment more quickly and resume production by viewing safety events via machine or system human-machine interface (HMI). More importantly, manufacturers can maintain and manage the safety areas independently during production, and operator and maintenance personnel can do their jobs (such as cleaning and checkup) without switching off equipment power supplies, shorten lockout/tagout time, and secure the safety of personnel.
“Investment in safety measures pays off as it is much lower than subsequent direct and indirect cost of accidents. Rather than a burden, safety is a way to differentiate yourself and increase benefit,” said J.B. Titus, certified functional safety expert [and Control Engineering Machine Safety blogger], who was invited to attend a safety conference in China. Integrating the safety function into products is also an important way to improve equipment performance and business achievement, distinguishing the manufacturer among competitors, as well as reducing the cost of accidents and medical expense.
Long-term view of safety
While safety integration can reduce risk and improve productivity, in practice many machine manufacturers are reluctant to implement integrated safety solutions. Rong Hua, China area manager of global standard and trade department of Rockwell Automation (China), suggested there’s an implementation bottleneck for safety integration.
- Machine manufacturers want to lower cost of equipment, while short-term expenses from the safety integration implementation will increase.
- Ensuring changes follow safety standards can be perceived as difficult.
- The end user is unwilling pay for safety and may disregard equipment operator safety.
All machine manufacturers want to realize maximum benefits while lowering costs. Companies with passive responses are more sensitive to immediate safety expenditures. Forward-looking companies consider the long-term benefit from safety integration. Are long-term or short-term benefits more important? This is a question worth considering. The company must have a long-term development view if it wants to grow and realize sustainable growth.
“Although it is hard for the safety control system to bring financial return in the short-term, it can function to avoid hazards in case danger occurs, and to avoid or reduce loss of environment, people, and property. This is the biggest benefit of safety integration,” Hua said.
Safety helps productivity contributes toward responsibility for and obligation to life, property, and environment. Enforcing safety consciousness is an inescapable duty. “It is necessary to communicate with the clients frequently, emphasizing that safety system enhancement is a competitive advantage,” Titus said. The client’s insisting on a higher attention to safety may finally force some machine manufacturers with poor safety recognition to implement safety control solutions. If safety is fully recognized by the machine manufacturers, it will be considered in the equipment design phase, which means that the popularization of safety concepts is basically successful.
“We work together with TÜV Rheinland to popularize international safety concepts, organize a safety solutions conference with partners, and promote the safety concept using all kinds of channels such as brochure, symposia, and press gatherings,” said Wei Liu, general manager of Wieland Electric (China), talking about how the company promotes safety products and solutions. It is not enough to rely only on a few companies’ efforts to change manufacturers’ attitudes toward safety. All parties need to be involved, Liu said, including the government, which enforces legislation, compliance, and standards for safety and public opinions to popularize safety concepts and consciousness. There is a long way to go, he suggested.
Key risks evaluation
It is impossible to achieve overnight high levels of functional safety and related benefits while minimizing hazards and losses. Functional safety is a systematic concept, not one product; it is also a continuous concept and needs to be reviewed until the end of system lifecycle. The functional safety lifecycle (defined in IEC standards 61508 and 62061) provides a fundamental framework for the “design integration” safety concept, and its target is to eliminate causes of accidents. By evaluating the risk of potential hazards and understanding the function and limitation of machines, a sustainable safety system can be developed, verified, and improved during its lifecycle in production.
“To achieve functional safety, companies should establish a feasible safety strategy, which is implemented from the top down. This is more than a technical issue. It is a management issue, and easier said than done,” Hua of Rockwell Automation said. Danger analysis and risk evaluation is the first phase of functional safety lifecycle.
Danger analysis analyzes potential risks related to machinery in the plant, including risk identification, risk quantification, and risk mitigation (see flowchart). It helps manufacturers to find the specific hazard in the machines, quantify the risk by analyzing the hazards, and lower the risk to an acceptable level. Conducting risk evaluation before design can secure the safety of personnel, process, and machinery and maximize the production capacity without affecting productivity.
“Bringing risk evaluation into the enterprise culture is helpful for safe equipment operation, lowers purchase and maintenance costs, and allows for easy adoption to continuously changing requirements,” said Titus.
After risk evaluation, the identified risks should be eliminated or mitigated as much as possible in the design phase. As to inescapable risks, the necessary safety safeguard measures should be taken; also, appropriate training should be conducted to ensure operators understand safety measures and personal safety equipment. These three measures work together to reduce potential casualties, environment damage, and property loss.
More manufacturers are realizing the importance of functional safety and are considering taking technical measures in the design phase to lower risk.
“If system development follows requirements of functional safety, the safety of the product can be improved greatly, and usability is one factor that the manufacturer should consider when designing products,” Bin Zhao of TÜV Rheinland commented. Integrating the safety system and the control system instead of adding the safety system to the completed product benefits all parties.
International safety standards
As updates occur in international safety standards, are we prepared?
With the technologies advancing, functional safety standards of machine control systems evolve continuously. Standards limit production activities within the scope of the standard so as to minimize hazards as much as possible. The new machine safety standard, EN ISO 13849-1:2008, established by the European Commission, took full effect on Dec. 31, 2011, replacing the EN954-1 standard. EN ISO 13849-1 (machine safety-control system, safety related parts) or EN/IEC 62061 (machine safety-functional safety of electric, electronic, and programmable electric control systems) have become the acceptable functional safety standards under Europe’s new machine directive. Both standards use different methods, but the result is the same. Each method is applicable to the target users.
New standards inherit some ideas of the old standards, follow the requirements of technology advances, and add some technologies, such as software. Functional safety application standards regulate the development of safety products, such as light curtains, valves, actuators, safety relays, safety mats, safety latches, safety controllers, safety switches, proximity switches, and safety scanners; every safety component must have the specific “possibility of dangerous failure” or “mean time to dangerous failure.”
Rockwell Automation has supported the new standards for a long time, company representatives said. Dan Hornbeck, manager of Rockwell Automation marketing, explained two reasons for this. First, new standards help users improve the safety of the complex machinery. Second, new technologies and design experience help the enterprise to improve the overall machine efficiency, productivity, and flexibility.
Following new standards, the machine manufacturers and system integrators can speed the application of new technologies to machinery; meanwhile, because of the complexity of functional safety standards and higher requirements of safety, safeguard costs of machines will go up, and complicate research and development for many manufacturers. To comply with new standards, many machine manufacturers and control system providers invest much time and money. However, according early 2011 Control Engineering research, many manufacturers are unprepared for the new standards and are seeking external assistance.
As for China, a major machine manufacturer, specific machine safety regulations and standards established by developed countries are like intangible trade barriers, hindering export of machines produced in China due to safety issues. With full implementation of the new European standards, the China manufacturing industry must improve product safety to open up the European market. When it comes to the impact of the new European machine safety standards on Chinese enterprises, Zhao of TÜV suggested that opportunities and challenges exist at the same time: “The urgent action that manufacturers in China should take is to learn how to comply with the requirements of the standards, evolve from low-value-added product manufacturers to high-value-added product manufacturers, and change the status quo of satisfying the requirement of standards only by purchasing certificated products overseas. If functional safety is considered as early as possible, we can bring great benefits for the enterprises.”
Hua of Rockwell Automation also expressed optimism about the future: “Many industries are enforcing the implementation of safety standards, and the market in China is huge if the environment changes.”
Enterprises in China must face EN ISO 13849-1:2008 actively, and it is a good opportunity to fully adjust machine standards in China. Currently, machine safety in China is classified into three groups: basic safety standards (Class A), common safety standards (Class B), and professional mechanical safety standards (Class C). Class A and Class B are usually recommended, and some safety elements are obligatory while some of the safety standards of product classes are obligatory. China is relatively behind developed countries in the areas of conception, system, and supervision.
Shu Zhang, Shanghai technology expert and professor at the Institute of Modern Manufacture Technology, Tongji University, said to CEC, “European new standards definitely improve the safety requirements of product imported to Europe. It is believed that China will establish new standards accordingly.”
The hidden causes of machine safety accidents and safety automation accidents may lie in the design of safety products and safeguarding solutions, but the root reason is the ignorance of and unawareness of safe production. Problems such as absence of management systems and unqualified staff are exposed in production safety accidents, which have garnered public attention in China. Now is a good opportunity for manufacturers in China to strengthen safety automation construction and to learn from advanced international safety standards.
Qin Li, chairman of the National Standardization Technical Committee for Safety of Machinery, said in a recent interview, “until we are geared to international standards, strengthen the research and promotion of machine safety, regulate safety design of products, enforce safety management, and reinforce market and consensus supervision, then we can implement safety standards in machine design, production, and usage, and reduce the number of casualties.”
Editor’s notes: Certificate for function safety, or so called SIL, is a third-party evaluation, verification, and certification that evaluates and determines the safety integration level (SIL) or performance level (PL) of safety equipment, based on IEC 61508, IEC 13849-1, and IEC 62061 standards. SIL includes evaluation of the file system management (FSM) of the safety equipment development process, calculation and evaluation of hardware reliability, software evaluation, environmental tests, and electromagnetic compatibility (EMC) tests.
– A shorter version of this article, from Control Engineering China, appears in the North American March Control Engineering print and digital edition. Edited by Mark T. Hoske, content manager, Control Engineering.