Lockout tagout, more commonly LOTO) is a temporary method to isolate an energy source utilising mechanical barriers or tags thus protecting workers from being exposed to a hazardous energy source or the energising of machinery that they are working on. Lockout Tagout is one term that is recognised worldwide but it describes two different processes. Lockout is the better choice because it uses a physical mechanical barrier, a lock, to isolate a process, the lock cannot be removed unless you have a key and generally the key is held by the person doing the work.
There may be more than one lock isolating the process or energy source but more of that shortly. The lockout method is preferred by most of the worlds Health and safety regulators as it a physical barrier. Tagout is still effective but obviously it would be easier, for someone not involved in the work, to remove the tag and open up a machine or system to an energy source which could have a detrimental effect to the person or persons doing the work. To use just a tagout requires the employer to demonstrate that it is an effective method to protect workers and there is no method to use a lockout.
When we are talking about an energy source we are talking about fuel, electricity, steam, fluids or gases under pressure, heat or batteries etc, anything that can apply a driving force or expose the worker to the source directly. In order to effectively isolate machinery or processes the lockout needs to be a physical mechanical barrier, one that ideally is controlled by more than one person. There are many devices that can be used such as safety padlocks, chains and hasps. Each device needs to be lockable and each lock can only have one accessible key, no duplicates, for obvious reasons.
LOTO can be implemented for small jobs that don’t take long or it might be a long period, especially if there is large connect process train such as in refineries. It can also be used for domestic purposes, the majority of consumer electrical breakers have a method for lockout, your local electrician will have a variety of small devices to use to protect him while he is working on your electrical circuits. In this situation he will have the key in his pocket and only he can remove the device.
For larger scale works there may be many sources of energy and several routes that energy can take. Usually a risk assessment will be made to identify all sources and paths of energy and where they can be effectively isolated. The risk assessment will also develop a lockout/tagout plan that will be communicated to affected employees prior to work commencing. Obviously with larger scale isolation’s there will be more people involved, not only those that will conduct the work on the isolated machinery or process but also the health and safety departments, the LOTO team and management. Large scale works need to be planned well in advance so that plant is not shut down for too long, permits need to be applied for and customers may need to be informed.
The planning also needs to address the conditions for removal of the LOTO and reinstating the machinery or process. For the larger jobs LOTO may involve multiple devices and multiple safety padlocks on each device. Safety padlocks come in different keying options depending on how your LOTO process might work. There are single/unique key padlocks, which is beneficial when many workers have their own unique padlock and key and only they can remove it. You can get a unique key that is paired to many padlocks, these are usually issued to workers that may have isolation’s to make and lastly you may get a set of padlocks that can be controlled with a master key. There are many types of padlock that retain the key until the padlock has been locked, this will prevent keys being lost or maybe found and unauthorised removal of a lockout device.
Usually safety padlocks will be identifiable to the owner in some way, they can be inscribed with a name or department or simply just colour coded. Padlocks also have to be durable, they may be exposed to inclement weather, be in place for long duration’s or exposed to chemicals of some kind. Safety padlocks are available in many materials and the choice of each will depend on the LOTO scenario. Steel padlocks are strong, corrosion resistant and durable but may over time become rusty. Aluminium is more resistant to chemicals and a popular choice in the food industry.
For electrical work or isolation a non-conductive variety would be a good choice, other materials are available such as composites. These tend to be very light and very resistant to most elements they may be exposed to. And of course there are a multitude of padlock manufacturers for LOTO applications.
When applying a lock out it is usual also to apply a tag as well. The tag will contain information for workers such as the person or persons applying the lock out, the reason for the lock out and how long it will be in place. Any affected workers can then raise questions to the correct persons if required very easily and get the answers they need. The tags need to be durable as does the ink used to write on them, it may be required to change the tags periodically especially if they are exposed to ultraviolet.
So lets review some steps required to successfully apply LOTO and conduct work safely.
- Preparation – We have already discussed earlier the need for thoughtful planning, no matter how big or small the task is. Risk assessments to identify the type and source of hazardous energy and communication of the need for LOTO has to be completed thoroughly.
- Shutdown – the act of physical switching off to stop machinery or a process.
- Isolation – This requires removing a fuse or shutting off at a breaker or closing a valve.
- Lockout/Tagout – now we actually apply the locks and tags. They need to be applied in such a way so that the breaker can be activated or the valve opened and putting a tag in place also.
- Stored energy check – After step 4 we cannot just start our work. It is possible that there is some stored or residual energy that need to be dissipated. We can check, for instance, that a machine does not activate by switching it on, if it does move or any other indication that power is still there such as a light illuminating than recheck the isolation. Pressure from fluids or gases can be bled off at a suitable point.
- Verification – Once we have all the applicable LOTO points addressed, we have checked for stored or residual energy it is time to bring in an authorised person to verify the equipment is safe to work on.
When our work is finished we can refer to our plan to reinstate the machine or process. Again an authorised person will ensure that all of the work has been completed as intended, that all work permits have been returned and the worksite has been cleared of all tools and materials. The Lockouts and tags can be removed by the person or persons that applied them and the control of machinery or process can be handed back to the owner.