Answers for LOTO Dilemmas
Applying risk assessment principles to a troubleshooting job can help you find many useful solutions.
IMPLEMENTING lockout/tagout on a machine is relatively simple: Just identify all of the energy sources, isolate the energy sources by turning off and or blocking or bleeding them, lock and tag the energy sources, verify it is locked out, and then do the work that needs to be done. The dilemmas start when you cannot do what needs to be done because you need energy on to do it. Troubleshooting, adjustments, set-ups, cleaning, clearing jams, and minor work that is so minor locking out just does not seem reasonable are a few of the many dilemmas workers and safety personnel struggle with every day. In this article, we will provide guidance and solutions to many of these common lockout dilemmas.
Have you ever seen a newspaper printing press running a long sheet of paper off a huge roll at one end of the press? How do they get the paper started through all the various parts of this machine? The paper must be started by feeding the end of it through a number of moving and in-running nip points. Often, hand feeding of the paper is the only possible way to do it. It is potentially very dangerous. Although lockout of the energy source is not possible, the hazards can be effectively controlled. The way they are controlled may be helpful to look at in solving your lockout dilemmas.
1. First and foremost is training of workers to recognize basic machine hazards such as pinch points and in-running nip hazards. Only well-trained and qualified workers should do this job. Training programs should be competency-based, which involves testing for skill and knowledge.
2. Loose clothing, long hair, and dangling jewelry present hazards that can be eliminated by workers and good supervision.
3. Speed of the machine is carefully regulated and kept slow to minimize the hazard. An audible warning such as a buzzer or bell often is used to delay any starting or movement long enough to warn workers of the start-up.
4. Anything and everything that can be enclosed in a guard is enclosed to prevent access. This includes gears, belts, pulleys, sprockets, and the like. Good supervision must ensure these guards are kept in place.
5. Multiple emergency stops are located within easy reach.
6. Many hazard locations are identified and re-enforced with warning labels.
7. Openings between rollers are kept to a minimum with the installation of finger guards. This allows the thickness of paper in but not a finger, unless you push very hard. Good supervision must ensure these guards are kept in place.
These are just a few of the controls that allow this lockout dilemma to be managed and the work to be done safely.
Compare the above to the lockout dilemma of programming or teaching a robot. You must have power "on" and be inside the safeguarded area. Sometimes in order to see the exact position of the robot end effector, you must be in very close to it, knowing that it could take your head off in a heartbeat! How is this done safely?
Start by reviewing the first six points above. They all fit in here very well! Add: a) the enabling device the worker must hold while operating the robot, b) inspection of the teach control prior to entering the cell, c) testing of the emergency stop prior to entering the cell, and d) the procedure that only those with an enabling device may be inside the safeguarded space while this is being done. Controlling hazards has been an accepted practice forworking around lockout dilemmas.
Troubleshooting and Risk Assessment
The list of situations where lockout is impossible goes on and on, but troubleshooting heads the list for the biggest number of lockout dilemmas. The troubleshooter has immediate access to potentially dangerous moving parts and energy sources because the guarding must be removed. Often, the power is on and there is a problem in the machine. Something is not working the way is it supposed to work. The worker's mind is focused on solving an electrical, pneumatic, hydraulic, or mechanical problem, or worse, a complex combination of them.
Unexpected start-up or release of energy while troubleshooting seriously injures or kills one worker after another, day after day, year after year. In this situation, never settle for a compromise to complete energy isolation and locking and tagging out all energy sources unless the work has been assessed by a knowledgeable team that develops the controls needed to do the work safely. To develop these controls and solve this dilemma, review the six points and then read the American National Standards Institute standard Z244.1-1982, Lock Out/Tag Out of Energy Sources and the ISO standard 14118, Safety of Machinery--Prevention of Unexpected Start Up. You will find these standards have considered a great number of issues you may not have thought of on your own. Some say each issue in these standards is written in blood.
The process your team of knowledgeable workers should follow to develop the controls needed for lockout dilemmas is called a "Risk Assessment." ANSI offers a good model to follow. The process has been refined much further in Europe, where safeguarding devices and controls have a control reliability rating called Categories.
"Risk Assessments" usually define risk as the probability of an accident, multiplied by the consequence, or seriousness, that would result if it happened. Probability is a combination of exposure to the hazard (the amount of time a given worker is exposed) and the likelihood of the accident/injury occurring.
Reducing the speed of the machine can reduce the likelihood of the accident by improving what I like to call the "duck factor." In the case of teaching a robot, the risk is reduced by the robot's being in a slow speed mode. The worker probably will have time to move out of the way. That is the duck factor. Or, the worker will have time to hit the emergency stop or will squeeze or release the enabling device, which in turn will stop the hazardous motion. In some situations, such as confined space entry, a second standby person is assigned to perform the duck factor.
Similarly, in some troubleshooting situations, a second standby person can stand watch with one hand on an emergency stop to perform the duck factor. This person must stay alert and be competent. By applying the risk assessment principles to a troubleshooting job, you may find many usable solutions to your lockout/tagout dilemmas.
Competency-based Training
- Once the team has developed the controls, a job procedure should be written up and competency-based training provided. Competency-based training has four elements:
- theory training
- theory testing and retraining
- practical training, and
- practical testing and retraining.
Only those who have demonstrated they are qualified by meeting rigorous testing for both theory knowledge and practical skills should be allowed to perform the job. This competency-based approach is a good way to conduct your lockout/tagout training, as well as training for lift truck and crane operators and any other high-risk job.
It may seem like a lot of work just to perform some routine troubleshooting or to clear a jam that only takes a few minutes. You do not have to solve all your dilemmas today--you only have to start and make a commitment to this process. Serious injuries and death can and will happen very quickly, and once they do, the clock does not move backward.
This article originally appeared in the March 2003 issue of Occupational Health & Safety.