OSHA and machine guarding: Aging standards
Not long ago, a maintenance employee working a 12-hour shift in a manufacturing facility was cleaning the light sensors of a robotic piercing machine. These sensors were used to detect slugs punched from metal parts. The worker placed the machine in manual mode and began cleaning the first of three sensors, which he accessed through the machine’s point of operation. As he was finishing his work on the second sensor, the machine cycled. Its hydraulic slide closed on the worker’s leg, breaking two bones.
What happened? The subsequent accident investigation and analysis brought to light a number of issues, but one among them was the failure of machine safeguarding and/or lockout measures to protect the worker adequately. An all-too-common problem in industry today, the incident happened, at least in part, because Occupational Safety and Health Administration (OSHA) regulations governing machine safeguarding have become inadequate and outdated.
Protection systems have not kept pace with advancing technologies. Modern, automated computer-controlled production systems—such as the robotic system in the example above—are more complex. They move faster. They involve more elements. Traditional single guarding measures described in existing OSHA standards often simply are inadequate. An employer may need to look at several safeguarding methods when automated equipment is involved. If a control component fails, a single guard is not going to help very much.
The drawbacks of growing old
“A robotic system containing many pieces of equipment in one cell must be viewed in terms of the total system,” says Jim Washam, safety consultant and partner, Machine Safety Specialists LLC, “including the sensors, controls, and electronic components, to provide adequate protection. And workers must be well trained to use—and maintain—these systems. You can never be quite sure if the equipment is in a stop mode or a pause mode waiting on some signal to start up.”
OSHA recognizes that its machine guarding standards inadequately address the issues of automated equipment. When developed and implemented some 40 years ago, Subpart O of the OSHAct of 1970, Machine and Machine Guarding, depended largely on its general clause, which said only that “one or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks.” (General requirements for all machines: 1910.212.)
Subpart O targets just seven machinery categories by name: woodworking, cooperage, abrasive wheel machinery, mills and calenders in the rubber and plastics industries, mechanical power presses, forging machines, and mechanical power transmission apparatus, leaving the general machine guarding clause to govern all other equipment. Further, OSHA regulations “don’t explain how to guard a machine, nor discuss safeguard quality, nor mention the control systems that are a frequent and integral part of machine safety today,” observes Washam. “Yet that paragraph continues to be used to embrace safeguarding for the overwhelming majority of machines and equipment in industry.”
Admittedly, the goal of the general clause is to cover all the bases. It allows OSHA representatives to inspect and impose penalties for any hazards found on any machine not named in one of the seven specific machinery categories, says Washam. “But while that may have worked in 1970 on traditional equipment, it is not sufficient for today’s sophisticated, complex automated systems.”
The rise of consensus standards
What, then, is sufficient? Because of the inability of OSHA standards to deal with many issues, says Washam, especially those associated with today’s complex systems, employers first need to understand that complying with minimum OSHA requirements—and doing nothing more—is unacceptable. “Doing the minimum,” he adds, “can lead to serious injuries, possible litigation, and more OSHA inspections.”
Because OSHA regulations offer little detailed information, Washam recommends manufacturers look for answers in current consensus standards—for two principal reasons. First, consensus standards, such as those developed by the American National Standards Institute (ANSI) and other industry standards-setting bodies (National Fire Protection Association [NFPA], Robotic Industries Association [RIA], etc.), help build a safer workplace. They provide guidelines for specific types of equipment, and they are usually current, normally undergoing revision every few years. And they offer detailed information for implementing safety systems and procedures. For example, ANSI/RIA 15.06: Industrial Robots and Robot Systems, explains robotic safety, including requirements for robotic cells, the quality of the safeguards, how to a perform risk assessment, how to determine potential hazards, hazard probability, and steps to take to provide protection.
Second, all indications are that OSHA is increasingly applying consensus standards to its inspection process as a way of bringing its regulations up-to-date. Although OSHA has not formally adopted consensus standards, inspectors are tending to use them to determine compliance. “It is not unusual for inspectors to recommend that employers use a particular ANSI standard as a guide for providing state-of-the-art protection, recognizing that the OSHA standard alone is now insufficient,” Washam notes.
OSHA is aware of its shortcomings. The agency is looking for ways to ensure better machine safeguarding and is finding ways to do that by using consensus standards as a way to measure compliance. Manufacturers may find it wise to do the same. Start by obtaining all consensus standards documents that pertain to your operation, recommends Washam. Study them, review them, and apply them. Then, when the OSHA inspector knocks, your facility will be ready.
For additional information on OSHA, safety standards, and machine safeguarding, visit these Websites:
www.ansi.org American National Standards Institute
www.dol.gov U.S. Department of Labor
machinesafetyspecialists.com Machine Safety Specialists, LLC
www.nfpa.org National Fire Protection Association
www.osha.gov/dte/oti OSHA Training Institute
www.robotics.org Robotic Industries Association
– Control Engineering tutorial, www.controleng.com