Assessing the Hazards
Sometimes there are inherent problems with equipment that are masked by efficient operators performing unsafe tasks.
- By Michael DeRosier
- Jul 01, 2004
WHAT do you really know about machine safety? Ask yourself, "Would I be comfortable working on this equipment? What if someone I cared about was working on this machine? A spouse? A brother? A sister? Would I want them working on a machine that is not safe?" If you answered no to any of these questions, why would you let your employees work on an unsafe machine?
Too many times, we walk into facilities and find operators, supervisors, and managers are under a false sense of security. They are surprised to learn about all the hazards that are on a machine. It is more often true than not that unsafe machines and equipment are not the result of fault, nor related to negligence. Lack of machine safeguarding is usually caused by a lack of knowledge and/or education specifically geared toward machine safety.
There is a growing need to reduce hazards in the workplace. Too often, machine safety is overlooked. Unfortunately, many times we are brought into a facility to help with safety upgrades after an injury has occurred, and sometimes as a result of a fatality.
Visible and Hidden Hazards
We can divide hazards into two groupings: visible and hidden. Visible hazards are clearly identified by OSHA under OSHA 1910 Subpart O--Machinery and Machine Guarding. Hazards or "points of operation" can include, but are not limited to, cutting, pressing, crushing, shearing, flying objects, etc., which can be visibly seen on a machine. These are not to be taken for granted.
There are several points to the design and implementation of visible guarding. The hidden hazards, the hazards that normally are missed, more typically are related to the control system. A control system contains any electrical, electronic, pneumatic and/or hydraulic portion of the machine.
As an example, take a walk on your manufacturing floor. You may walk up to a machine and see the best guard that took both ergonomic and aesthetic considerations into the design. Open the door, and you may find a simple, non-safety rated plunger switch that is being used to shut down the machine. At this point you may be asking, "What does that mean?" or "Why does it matter if the machine shuts down?" First, a plunger switch is too easy to bypass; it would shock you how many times you find a piece of tape over the switch or a wire tie holding the plunger down. If you ask someone the reason for this, you may hear answers about saving time and money due to jams or changeover. Operators also claim they need to access the machine while it is running.
Now that we have identified a weakness in the control system, the obvious way to fix this is to replace the plunger switch with a safety rated switch that is more tamper resistant and difficult to defeat. You think you have the problem licked, right? Not yet! Did you look at the wiring behind the switch? This may be a single contact setup in which a single short would cause a failure of the switch. Is the switch a simple input to a PLC or computer? The code can be changed easily or fail. Is the switch monitored for functionality? As you can imagine, many scenarios can be played out in stopping that machine.
From this point, what about failures from the outputs? Relay contacts can weld and valve spools can stick. Where does it end? Where does it begin? What do you do? There are so many questions, and you may not have all of the answers. Any of the failures mentioned above can prevent the machine from stopping as it should, which would make the likelihood of someone getting hurt or killed a high-risk reality. A systematic approach can simplify this whole process for you.
What do you do to identify and reconcile visible and hidden hazards? The process is as follows:
1) Risk Assessment
5) Risk Assessment
First, you must determine whether you have the capabilities within your company of performing any of the tasks in the process. Frequently within a company (with or without a safety department) you may not have the experience or resources to perform these tasks on your own. Most safety professionals have a very strong background and know-how--but as long as the need for machine guarding has been around, they may have lacked the education or know-how to get what they need. In cases like this, you would hire specialists in machine safeguarding to help you with the process and educate your employees.
Once you have identified your resource for approaching machine safety, you can begin your process by performing a risk assessment. A detailed risk assessment would identify every hazard on the machine, both visible and hidden. Please be aware that all hazards you identify must be resolved by law. You also must understand some of your findings may not be answered with a simple yes or no.
Assign a risk level for each identified hazard. This helps to determine the urgency and priority that can be placed on a resolution and the level of safety required for the control system. For example, a low-risk, low-hazard system may require only a single channel, unmonitored design. However a high-risk, high-hazard system would require redundancy on both inputs and output safety devices with constant monitoring for failures.
Organizations in the industry can help to define this process in detail. For example, the American National Standards Institute has published ANSI B11.TR3-2000, Risk Assessment and Risk Reduction--A Guide to Estimate, Evaluate and Reduce Risks Associated with Machine Tools. It is important when performing your assessment that you listen to all departments that work on the equipment, such as production, maintenance and engineering. A risk assessment is critical in being able to move to the next step.
Your design stage can be considered a think tank. There may be several approaches and concepts for developing a solution for the hazard. The trick is to develop a concept to meet all appropriate OSHA and industry guidelines for safety, while making it user friendly and the most economically sound or feasible. Review the designs with your employees.
When you design guarding for the visible hazards, there are several ways of accomplishing this. Fixed and moveable barrier guards, presence sensing devices such as light curtains, tooling, and walls are all forms of these types of guards. These designs are intended to keep a person from contacting the hazard point.
Designing for hidden hazards has several levels for determining the level of safety required for the control system. Safety components should be third-party approved and proven.
1) Single Channel Non-monitored--Used in place of conventional parts.
2) Single Channel Monitored--Used in place of conventional parts, as well as a form of monitoring designed in for failure identification.
3) Dual Channel Monitored--Components used should be redundant in construction and have monitoring designed to detect any single component failure.
4) Dual Channel Continuous Monitored--Components used should be redundant in construction and have continuous monitoring designed to detect any single component failure, in some cases detecting a failure before it occurs.
These requirements are determined by performing a risk assessment as stated in the first step of the process. The above levels are simplified for explanatory purposes, but the actual analysis will help you in deciding what should be the proper protection method for your needs.
I hear three arguments all the time as to why machine safeguarding would not be required. The first: "Why do we need to do this? I have worked on this machine for 15 years and have never been hurt." The point already has been missed; the concept is to reduce the possibility of getting hurt both now and in the future. There is no doubt operators get to know their machines better than anybody and may be able to avoid injuries, if they are fortunate. What happens if they are sick, they retire, or an additional shift is put on? What happens to the new operator on the machine who does not know the ins and outs as well as the veteran?
Second: "If you add guarding you will slow down my productivity. I will not be able to access everything I need to in order to clear jams or problems as quickly as prior to the guarding." In many cases, you may see productivity increase. Sometimes there are inherent problems with equipment that are masked by efficient operators performing unsafe tasks. This forces you to fix the problems, thus reducing downtime.
The most frequently heard argument: "Why are you guarding this? Someone would have to be stupid to stick their hand in there. And if they do, they deserve what they get." Too often, operators are undervalued. Operators become quick and efficient at doing their job. They would have the ability to run circles around anyone who does not use the machine as they do. We must not forget about human nature. The typical response to an immediate problem is to fix it. For instance, if all of a sudden you see an object coming at your head, what is your reaction? Your arms and hands go up to protect your head. Your reaction is instinct and not from careful thought. The same holds true for operators on their machines. Something has jammed and can cause a major downtime problem. Their instinctive reaction is to get, grab, pull, and clear the problem. The act they are performing is not stupidity, but reaction.
Fabrication and Installation
After the design is finalized, fabricate necessary parts, components, tools, circuits, and fixtures to install the guarding properly. You now are ready for implementation. Make sure you have qualified personnel performing the installation to meet the OSHA standards and industry guidelines.
Risk Assessment and Validation
Why do a risk assessment again? You want to ensure each hazard has been taken care of, and because changes have been made to the equipment, you want to ensure no new hazards were created. Repeat this process to reduce all hazards to an acceptable risk.
Validation may be specific to the safety control system for functionality or may be required for an entire process related to your company policy or industry and federal requirements.
What is the Cost?
Hiring a specialist will help you determine your concrete costs. Do you know which other factors can help keep costs to a minimum?
Set up a design criteria guideline for your equipment vendors. Make sure new equipment purchases are made to OSHA standards, industry guidelines, and any additional standard above and beyond that you will require for protecting people. It is very costly to receive a brand-new piece of equipment, go through validation, be required to perform safety upgrades, and then validate the machine again.
It is also important to develop your criteria and specifications as a company standard for all new equipment purchases. It is most cost effective to make the vendors aware of these requirements during the quoting stages. If this is done after the purchase order is sent, you are very likely to receive additional charges to meet the proper safety specifications. Just sending a written specification is not enough; an open line of communication is key to getting exactly what you require. There may be different ways to interpret a standard, and the vendor may differ from your understanding and requirements.
Why don't some vendors have proper safety guarding packages? The most common reason we hear is cost. The vendors have difficulty competing becuase they lack education and understanding of safety requirements. Depending on the equipment, vendors don't always know how the machine will be interfaced, and they rely on the customer or integrator to add the appropriate guarding techniques.
Ultimately, it all comes back to the customer. Until more customers require their vendors to meet safety standards, guarding in a lot of cases will be only an option, not a standard design. Remember, these statements are making very vague generalizations. This is why it is important to research, educate, and communicate with your vendors. Some machine manufacturers that have a very good grasp on machine guarding and have made it a requirement for all of their designs.
What is the cost of not bringing machines to current safety guidelines? First, if OSHA identifies hazards, you will be fined and will be forced to resolve the problems. You may not realize this cost may be minimal compared to someone getting hurt or killed out of negligence. Take a look at all the direct and indirect costs in this case--you'll see lost work days accumulated, as well as the possibility of rate increases for insurance, loss of insurance, lawsuits, production loss, reduction of morale, etc. You can clearly see the cost can be much higher than you ever imagined.
An unfortunate thought always needs to be in your mind when looking at machine safety and evaluating the cost. Envision yourself working on the machine. What do you see that you need to be protected from? You do not want to be a person who is killed or maimed by a machine. There is a tremendous amount of emotional and psychological pain and anguish that will endure a lifetime.
Time to Get Started
It's time to start the process. Evaluate your capabilities and determine whether you need a specialist to assist in establishing a safe work environment for your employees. Don't hesitate and risk your fellow employees longer then necessary.
Each machine has its own set of challenges and requirements for proper machine safeguarding and machine interfacing. Whether you perform machinery safety upgrades because it is the right thing to do or because by law you must protect your employees, the key is to perform the upgrades. What value do you now place on machine safety?
This article originally appeared in the July 2004 issue of Occupational Health & Safety.