Energy can, of course, be in any form – mechanical, thermal, chemical, electrical, hydraulic, pneumatic, etc. It can be stored, potential, or live or kinetic. The unintentional release of any form of energy can present a hazard, and the greater the amount of energy released, the greater the hazard.
Machines and equipment, as with humans and animals, are driven by energy, and that energy can flow at any rate of transfer, where power is defined as the magnitude of energy transfer over a period of time. While is that one reason why “power lockout” is often used rhetorically with or instead of “energy lockout”, the physical difference is an important one. Energies that were employed and/or stored over long time periods can be released in faster and more dangerous ways.
Another important point is this: laypeople often think of “power” in terms of electricity only, and further in terms of volts and amps. Not only is this one reason for the oft-used caution “It’s not the volts that kill you, it’s the amps”, it ignores all the other fast releases of energy that can injure or kill. So, not only can an electrical line to a 100 ampere (A), 240 volt (V) motor operating at 100 A * 240 V = 24 kilowatts (kW) kill you, so can an otherwise innocuous 24 gram (gm) bolt if it was unexpectedly shot out of a spring-loaded system at very high speed after the motor had been used to compress the spring at very low speed, and that spring was unexpectedly released. (This example is sadly translated from a real-world industrial accident relayed to the author by an attending medical practitioner, where the fastener was propelled into the victim’s brain.)
For the purpose of this article, as well as to treat all hazardous energy storage and releases with the requisite caution, we shall treat all forms of energy as basically equivalent and reinforce that their all controls require equal focus and implementation. Also for the purpose of this article going forward, the word “equipment” can be considered to refer to any machinery, equipment, or powered tool, be it stationary, portable, large or small.
• The properly trained and authorized personnel who are to work on the equipment must review, document, and check all potential energy hazards – inputs, outputs, and storage.
• The equipment must be shut off and de-energized using proper power-down procedures.
• All energy inputs to the equipment must be turned off, disconnected, and locked-out by the individual personnel properly trained and authorized to work on each particular input, and only by those so trained and authorized, to prevent unexpected re-energizing.
• All remaining energy that could be potentially released hazardously must be properly dissipated by the individuals properly trained and authorized to dissipate each particular remaining store of energy, and only by those so trained and authorized.
• All of the above steps must be physically verified and checked off at each step to help ensure and document that they are followed.
While the phrase “lockout/tagout” could be taken to imply that visual signs like tags could be used interchangeably like locks, this is incorrect and a dangerous misinterpretation. The locks are to positively, affirmatively prevent the energizing of, or release of energy from, the equipment. The tags are to visibly and explicitly show that work is being performed on this potentially hazardous equipment and that no unauthorized energizing of and contact with the equipment is allowed.
Tagout by itself must only be used when energy control at a specific point simply cannot accept and retain a lock. Then, a durable tag, easily understandable by all staff on-site and controlled exclusively by the properly trained and authorized personnel, who shall be the only one(s) allowed to removed it, can be used as a warning of the energization hazard that particular de-energized point presents.
After all proper and authorized work has been safely finished and verified, the following step to re-energize the equipment must be followed:
• All personnel are individually confirmed that they are not at risk from the reenergizing of the equipment.
• Only the authorized personnel who locked and/or tagged out the individual energy inputs remove the locks and tags they are responsible for.
• Only the personnel authorized to reenergize the equipment may now do so.
• Only the personnel authorized to bring the energized equipment back into operation may now do so.
• All of the above steps must be physically verified and checked off at each step to help ensure and document that they are followed.
In order to ensure that all of the required steps above were properly done and documented, lockout/tagout should not be performed without two or more trained personnel present. This will help ensure the steps are properly executed and documented. Most importantly, as with all potentially hazardous operations, if any injuries occur during these steps, the other person can help the injured party and hopefully mitigate any other risks to health and safety.
Required organizational culture behaviors
Some important notes about expertise, confirmation, documentation, and organizational culture are needed here. Once someone has gotten used to doing some set of tasks, particularly repetitive ones, over time human nature sets in and less conscious attention is paid to the details of each step. The steps can become as unconscious as walking, more dependent on “muscle memory” than anything else Which works well until something unexpected causes us to trip up. Once grown, we may consider ourselves experts in tying our shoes, sometimes not even looking. Yet name one adult who has never improperly tied a shoelace. Or intended to double knot a lace and didn’t, noticing only when the lace became unexpectedly undone – hopefully before an accident subsequently occurred.
There is a reason even seasoned airplane pilots and crew use a checklist before they take off. Even after 1,000 flights, they and you don’t want to be on the 1,001th flight where they forgot some small, quick, but potentially life-critical task. There is a reason why surgeons and surgical staffs lay out their instruments in a visually verifiable manner, then confirm which ones are picked up and used when. As expert as they all are, they and we are all human and can and will make mistakes. The key is to minimize them by trying to drive their occurrences to zero, and guiding and verifying the steps taken with those goals in mind.
Any and everybody working with or near potential hazards such as energized equipment, no matter the level of training and experience, is human and can make such mistakes. The risks of working with and around energy sources that can be unexpectedly released, especially when a feeling of safety overly derived from the experience present takes over the required caution, can be fatal. All of the required steps above must be verified and checked off to guide and document the overall process. Shortcuts should and must be recognized as life-threatening, and as such, absolutely forbidden.
Even under the tightest time constraints, under the most demanding of schedules, and yes, most demanding of bosses, organizations must put safety above all else. In order to maximize safety and minimize hazards from occurring and harming anyone, and to keep the operations running smoothly for said demanding boss’ own self-interest, the organization from top to bottom must prioritize safety in operations, servicing, and maintenance. Period. Service and maintenance steps, and personnel, must be granted the same consideration, respect, resourcing, and reward as operations. And consistent documentation of operations, servicing, and maintenance steps – especially those dealing with potential health and safety hazards as above, must be granted even more respect, resourcing, and rewards as documentation of profits and losses. There can be no profit without the workers who safely and thus consistently operate and produce the output needed for those profits, and for the bosses’ political and financial success. As most bosses, executives, and officials visit such operations at least once, their safety is also on the line.
Workers’ self-interest is to return home each day safe, and still employed. Most want to operate safely if for nothing other than self-interest, and most workers with increasing experience derive professional satisfaction from seeing their work executed well and being respected, recognized, and paid for such. However, if the organization allows shortcuts to be taken, or worse, discourages steps that are directly or indirectly treated as unnecessary and opposed by management or co-workers, such corrosive behavior often leads those workers to default to the only self-interest that seems left to them – employment over safety.
In countries rich or poor, those women and men who want to return home each night safe and employed can find their backs pressed to the wall and determine that the next day finds them at lest employed if not safe. Emergency rooms worldwide can sadly attest to that. The rationalization that “it” won’t happen, or that “it” will happen to someone else can set in, and is hard to fight when the boss and colleagues are doing the pressing, bills are due and food needs to be put on the table. Without someone to return to that table, however, no such risks or rationalization will ever prove worth it. And the risks often are not contained just to one person, low or high on the ladder.
Small businesses, medium and large firms, parastatals, and governmental operations must both explicitly and implicitly reward, recognize, and demand that safety come before all else. Explicit operational steps, controls, verification, and documentation must be consistently and unconditionally deployed from the top to the bottom of the organization. Spoken and unspoken cultural norms help guide and manage behaviors in families, towns and village, and nations, often to a greater degree than laws will. The same holds for the internal cultures of organizations. If there are rules that nominally require safe behaviors at least in word, but the culture of the organization is to shortchange or discourage them, they will be shortchanged. If on top of that, workers’ personal incomes seems dependent on them going along with this, they will feel forced to and only those who can afford to do otherwise will leave. The rest will be forced to accept personal risk to their health and safety, no matter what the rules or the boss alleges to say.
If the rules “say” only a trained and authorized hydraulics specialist disconnects, locks out, services, then reconnects a high-pressure oil line to a machine, but everyone waiting around says “Let the electrician do it”, the risks of a flammable, energized oil leak spraying over not just the electrician but those gathered, and the rest of the operation’s factory can become fatal in an instant. The culture of any industrial organization must do everything to preclude this at all costs.
Keyed padlocks – These should specifically not be keyed alike in the same facility, meaning no one key or set of keys can open more than one lock anywhere on that site. This is so that when one person locks anything out – door, power switch, etc., – no other person on site has any other keys that could either purposely or mistakenly unlock it before the proper time. Many standard, simple low-cost padlocks may be mechanically strong but not appropriate for the job. Or they may be keyed similarly, so that one key can open a number of different locks, thereby letting people unlock and introduce hazards when they have no business doing so. Lockout padlocks with hundreds, thousands, or tens of thousands of verifiably unique keys are available on the market. However, if and where these are not affordable, otherwise appropriate locks with verifiably distinct and documented keys, cross-tested and verified against operation with all other locks on the premises and preferably the whole organization, may be acceptable.
Lockout hasps – These are steel or spark-resistant tags-shaped clips which swing open and closed (almost like scissors or flat tongs) with more than one through-hole to allow for more than one padlock to be applied to a locking point at once. So, for example, if a hydraulics technician, a pneumatics technician, and an electrician all have to perform, and verify, lockout on a machine and need to lock the main control panel to do so, each of the three people would have their own specific padlock and their own related unique keys to lock the hasp and “triple-secure” the panel. In order to unlock the panel and re-energize the machine, each person would have to approve and use their own key to unlock their own padlock from the hasp. The hasp then could only open and allow access to the panel when all three locks are released. If, for example, the electrician and the pneumatics technician feel it’s OK to proceed, but the hydraulics technician has not determined that it is ready, his or her lock just by itself would still keep the hasp shut, and the panel closed.
An example of a lockout hasp with six lock holes, and two numbered padlocks for two separate individuals, where the hasp’s steel fingers are subsequently locking up a hoist brake, may be found here:
Another example of a lockout hasp, and the electrical plug it is locking out via an enclosure, may be found here:
Energy source identification tags – These graphical, color-coded tags denote what potentially hazardous energy sources are present in that equipment – electrical, thermal, gaseous, mechanical, gravitational, etc. They are located at the individual points of energy. The tags are numbered per energy type, so that if, for example, there are three mechanical energy sources, two thermal, and one electrical source, there may be tags that say “M1”, “M2”, “M3”, “T1”, “T2”, and “E1”. If mechanically there are two rotating bodies which may have rotational inertial kinetic energy that might need to be dissipated, there may be two tags that say “DR-1” and “DR-2” to show the authorized personnel need to “dissipate rotation” at those particular locations.
Examples of such source identification tags may be found here:
Energy source isolation placards – These graphical, colored placards posted on the equipment list and visual what potentially hazardous energy sources are present, where they specifically are at around the machine, what lockout devices are required, and what de-energizing and lockout steps are required.
Examples of such isolation placards may be found here:
A good resource for learning and training on lockout/tagout is from the United States Department of Labor’s Occupational Safety & Health Administration (OSHA). OSHA is well known for regulations, practices, and enforcement of worker safety and equipment standards. Their “Lockout/Tagout” overview and tutorial for energy hazard control and lockout