1. INTRODUCTION
Lockout means the use of locks to secure devices that are used to control the energy in machines or systems.
In other words, preventing a control device from accidentally or inadvertently being operated while workers are performing maintenance.
It maintains the control of hazardous energy.
Maintenance is the work of keeping machinery or equipment in safe operating condition:
repairing, adjusting, cleaning, lubricating, and clearing obstructions.
Hazardous energy is an energy source that could release or move and endanger a worker.
Hazardous energy sources include:
Kinetic energy: moving equipment or moving materials
Chemicals: flammables, combustibles, and corrosives
Potentials: suspended, elevated, or stored energies
Thermal: steam, hot water, gases, and liquefied gases
Electrical: conductors, motors, and generators
Radiation: non-ionizing radiation like light and lasers, and ionizing radiation like x-rays
Lockout ensures control devices remain in a de-energized state.
A control device is a device that controls the flow of energy to machinery or equipment –
a switch, a circuit breaker, a valve – but is not limited to these examples alone.
It may also include any means used to control hazardous energies.
It is critical that each field officer clearly understands required maintenance and lockout procedures.
When he sees a worker working on equipment that is not locked out, he must issue compliance orders.
The officer must also initiate a penalty review of the firm.
If the lockout violation was a result of a worker’s carelessness, neglect, or was willful,
an observation report can be issued to the worker.
2. WHEN TO LOCK OUT
When is lockout required?
When the health or safety of a worker could be endangered if hazardous energy is released.
In determining whether or not a situation requires lockout, the following is a possible decision path:
Step one: View the location where the work is to be conducted
Step two: Identify all energy sources
Step three: Ask what would be the result if any of the energy sources were released?
Would there be no result? Or would the release of energy be hazardous to a worker?
If your answer was a no result, workers will follow normal safe working procedures.
If your answer was yes, then control devices must be used to isolate the hazardous energy and lockout may need to be applied.
3. LOCKOUT PROCEDURES
Through training, every worker must know the five basic steps of lockout procedure.
1. Identify the equipment or machine that needs to be locked out.
2. Ensure that the machine is stopped.
3. Identify and deactivate the main energy source.
4. Apply personal locks to the energy source.
5. Ensure that the lockout is effective.
This basic five-step procedure will always be followed when locking out.
The most common energy source to which lockout must be applied to is electrical.
Two types of wiring are common in equipment using electricity as an energy source:
plugged-in equipment and equipment that is permanently connected or hard wired.
When working on plugged-in equipment, such as a radial arm saw,
the worker shuts off the saw, unplugs it, and places the plug in plain view.
In this case, an application of a lock is not required as the plug is under the worker’s control.
When working on hard-wired equipment, identify the machine, ensure that the machine is stopped,
look for the electrical source, and disconnect it.
If required, apply lockout and ensure de-energization is effective.
Two important points that must be followed if a stop-start test is used are:
check all personnel are in the clear and return the control to the off or neutral position.
If an isolated control device is within sight and reach of a worker at all times during maintenance, a hazard assessment must be done.
This determines if there is a risk to the worker and whether or not a lock must be applied to the control device.
Interlocked systems have to be identified for lockout purposes.
This is an example of an interlocking system:
If conveyor #3 is not running, conveyors #2 and #1 will not operate.
If conveyor #2 is not running, conveyor #1 will not start, but #3 can operate.
If conveyor #1 isn't running, conveyors 2 and 3 will operate.
When testing a component of an interlocked system, either the interlock has to be satisfied or bypassed,
or other means must be used to verify the control device has been disconnected.
For example, if we wish to lock out #2 conveyor, we complete the five lockout steps.
However, to implement a true test, all downstream components must be operating,
thus satisfying the interlock.
Other common energy sources to be locked out are hydraulic or pneumatic systems.
The same five steps are followed.
For example, a cylinder which operates a drop gate:
First, stop the machine.
Look for the energy source and disconnect it.
This can be accomplished in two ways:
One, disconnect the electrical power to the pump or compressor, or two, close the valve feeding that cylinder.
Apply a personal lock to the electrical disconnect or the valve.
Ensure de-energization is effective by testing that the pump of the compressor won't start or the flow doesn't bypass the valve.
It may be necessary to pin or block a drop gate or a weight supported by the stored pressure in a cylinder.
Ensure that there isn’t any residual pressure in the lines, reservoirs, or accumulator feeding the cylinder.
Workers may have to bleed any residual pressure.
4. MULTIPLE POINT LOCKOUT
To effectively lock out equipment with multiple energy sources, it is necessary to lock out multiple disconnect switches.
Cables may be used for securing several disconnects.
The cable runs through the lock hole in each switch to be locked out.
After the final switch is secured, a lock is placed on the cable eye.
In this case, one end of the cable is fixed to a point at the motor control centre.
The opposite end has an eye that will accept a lock.
If more than one person is required to lock out, a scissor adapter may be required.
It may be necessary to post a specific multiple switch lockout procedure.
5. KEY BOX PROCEDURE
Key box procedures are frequently used to lock out equipment with multiple lockout points.
This equipment is found in process industries, such as pulp mills,
where 20 workers could be involved in a maintenance shutdown involving up to 50 separate energy sources.
Obviously, it's time consuming and expensive to provide 1,000 locks.
Following a key box system, the number of locks could be as little as 120.
Here's how a key box system works:
In this example, two qualified workers each take 50 locks
and a checklist for the 50 lockout points required for the maintenance shutdown.
On every listed control device, both workers install a lock and complete the checklist.
When all the 50 points have been locked out, both workers place the keys for the locks in a lockable key box.
Each worker signs the checklist and posts it by the key box.
Both workers may then lock the key box or place a positive sealing device that has a serial number on it on the key box.
The serial number of the seal would be recorded on the checklist.
This seal must be broken to get into the key box.
Any worker working on locked out equipment marked on the key box checklist must check to ensure the seal and seal number correspond,
and then place his personal lock on the key box.
When finished, he must remove his lock.
When the job is complete and all personal locks have been removed from the key box,
two qualified workers will break the seal and remove all the locks from the control devices.
6. LOCKOUT POLICY
Every company that is required to apply lockout must have a lockout procedure.
Large or complex firms may have a lockout policy to complement the procedure.
This policy becomes their plan of action.
A lockout policy should state that all workers must lock out when working on equipment.
It could also include:
Written safe work procedures for working on equipment that must be energized
Ensuring that only the part of the equipment that is vital to the process is energized and that workers are fully trained and authorized.
Rules for labeling and assignment of locks
There must be a system that will identify the owner of a lock; combination locks are not acceptable.
Rules for multiple person lockout
Each person working on the machinery is responsible for locking out the control device.
Multiple locks can be applied with scissor adapters.
Rules for multiple person lockout testing
The first worker who applies his lock must ensure the effectiveness of the lockout.
Rules for lock removal
The person who applied the lock is responsible for removing it.
If it is the last lock, he may be responsible for ensuring the machine is safe to re-energize.
Continuity locks
There may be occasions when lockout must be maintained between shifts.
In these cases, a continuity lock will be applied by a supervisor.
Emergency lock removal
The designated supervisor may remove a lock only after every effort to contact the owner of the lock has been made
and the machine is determined to be safe to operate.
The incident should be documented.
Rules for contractor coordination
Companies must require that all contractors meet lockout requirements.
7. SUMMARY
Training and supervision are the best methods to ensure workers lock out.
The WCB (WorkSafeBC) requires that workers will be trained to a level of demonstrated competency.
The WCB also requires that workers be supervised in lockout as they would be in any other task.
The use of safe work procedures for maintenance and production is of key importance.
When lockout is required, it must be implemented.
It is imperative that workers, employers, and supervisors understand and use a well-established lockout system.