Isolation of Plant Procedure

Purpose

The objective of this procedure is to establish a consistent method for isolating plant and machinery to ensure the safety of all personnel. The primary goal is to prevent the uncontrolled release of hazardous energy, including electricity, hydraulic pressure, pneumatic pressure, steam, gravity, and stored mechanical energy. This procedure aims to eliminate the risk of injury or death during maintenance, repair, cleaning, or adjustment work. By following these steps, we ensure that machinery cannot accidentally start up or move while a person is working on it. This document fulfills our legal duty to provide a safe workplace and to manage risks associated with plant equipment.

Scope

This procedure applies to all persons working at or visiting our workplace where plant and machinery are operational. This includes employees, contractors, subcontractors, labour hire workers, apprentices, and visitors. Anyone who is required to perform maintenance, service, installation, cleaning, or inspection on plant covered by this document must follow these rules.

The scope covers all items of plant and equipment defined as regulated plant under the Work Health and Safety Act 2011 (Cth) and corresponding state legislation. This includes, but is not limited to, machinery with exposed moving parts, electrical switchboards, compressors, pumps, conveyors, presses, and any equipment where unexpected energization could cause harm.

This procedure is mandatory for all tasks that require access to dangerous parts of machinery or where a guard must be removed. It applies whenever the isolation of energy sources is required to perform the task safely. It must be used in conjunction with relevant Australian Standards, specifically AS/NZS 4024.1 (Safety of Machinery) and AS/NZS 2441.2 (Locking out of electricity supply).

Managers and supervisors must ensure that all relevant personnel are trained in these isolation procedures. Supervisors are responsible for verifying that isolation points are identified clearly and that lock out and tag out devices are readily available. If a specific task presents a unique hazard not covered by this general procedure, a specific risk assessment must be conducted before work commences. This procedure remains in force at all times and overrides any production pressures that might encourage taking shortcuts with safety.

Identifying every potential hazard is the first critical step before any isolation work begins. You must assess the machinery or plant to find all energy sources that could cause harm. This process is not just about finding the main switch. It involves looking for stored energy, residual energy, and any secondary sources that could restart the equipment unexpectedly. Under the Work Health and Safety Act 2011 (WHS Act) and the Work Health and Safety Regulations 2011 (WHS Regulations), persons conducting a business or undertaking must manage the risks associated with plant. This starts with a thorough identification of specific hazards.

Electricity is a primary energy source. You must identify incoming supply voltages, including high voltage and low voltage feeds. Look for capacitor banks in circuits that can store lethal electrical charges even after the power is turned off. You must also consider backup generators or uninterruptible power supplies that could kick in and energize the circuit.

Hydraulic and pneumatic systems present significant dangers. These systems operate under high pressure. You must identify accumulators, cylinders, and flexible hoses that can store energy. If a valve is accidentally opened or a line leaks, pressurised fluid can inject into skin or cause moving parts to swing violently. Gravity is another energy source that is often overlooked. Raised machine parts, such as arms, blades, or heavy containers, possess potential energy. If a hydraulic system fails while you are working on it, these parts can fall and crush you.

Mechanical energy in moving parts requires strict attention. This includes belts, pulleys, gears, flywheels, and conveyor belts. You must ensure these parts have completely stopped moving before you attempt an isolation. Be aware of coiled springs or tensioned cables that may release stored energy suddenly.

Thermal energy is another major hazard. Identify steam lines, hot water jackets, or any surface that retains heat after the system is shut down. Similarly, cryogenic fluids or extremely cold piping can cause freeze burns or material failure.

Chemical and kinetic hazards must also be considered. Pipes may contain hazardous substances under pressure that need to be drained or flushed. Kinetic energy involves momentum in large machinery, such as large fans or mixing drums, which continue to spin for some time after power is cut.

Refer to AS/NZS 4024.1:2014 (Safety of Machinery) for detailed guidance on identifying energy sources. By listing every hazard and energy source specific to your site, you meet your duty of care and ensure the isolation process is effective.

Follow these steps to shut down the machine and apply locks and tags correctly.

1. Notify all affected employees.
2. Stop the machine.
3. Isolate the energy source.
4. Lock the isolation point.
5. Tag the isolation point.
6. Clear the work area.
7. Test for zero energy.

You must manage dangerous energy sources to prevent tragedy. Australian law requires you to eliminate risks so far as is reasonably practicable. When isolation is necessary, you must follow a strict system. The model Code of Practice on Managing Risks of Plant in the Workplace supports the model Work Health and Safety laws. It states that you must use lockout and tagout devices to stop energy from being restored while someone works on the plant.

Start by speaking to everyone who operates the machine or works nearby. Tell them you are about to shut it down for maintenance. This simple step stops someone from starting the machine while you are close to moving parts. Use plain language and make sure they acknowledge the warning.

Move to the operator station and shut down the machine using the normal stopping procedure. Never just hit the emergency stop button for a routine shutdown. Let the machine come to a complete standstill. Wait for all rotating parts to stop moving.

Locate the energy source. This might be an electrical switchboard, a gas valve, a steam valve, or a hydraulic supply. You must turn the machine off at the main source, not just at the control panel. Turn the switch to the off position or close the valve firmly. Do not rely on someone else to isolate the power for you. You must control the isolation point personally.

Apply your personal lock to the isolation point. Use a lock that is unique to you. Do not use a generic lock that anyone might have a key for. If multiple people are working on the same machine, each person must apply their own lock. This ensures the machine stays off until the last person finishes. If you cannot lock the switch, use a hasp that allows multiple locks.

Attach a dangerous energy tag to your lock. The tag must warn others not to operate the plant. Write clearly on the tag. Include your name, the date, and the reason for the isolation. Never remove a tag or lock that belongs to another person. If the owner is not available, a manager may remove it only after following a strict verification process to ensure the person is not inside the machine.

Clear the immediate area of tools and loose materials. This removes trip hazards and ensures you have a clean workspace to test the machine.

Test the machine to verify zero energy. Press the start button to confirm the machine does not move. For electrical equipment, use a voltage tester to prove the circuit is dead. For pneumatic or hydraulic systems, verify the pressure gauge reads zero. You must perform this test while your lock and tag are in place. Never rely on a past test. If the machine starts or energy is present, stop immediately and recheck your isolation steps.

You must verify that every energy source is isolated and the plant is in a zero-energy state before starting any work. This is a critical safety step. You cannot rely on locks and tags alone. You must physically test the machine to ensure it will not operate.

First, check that all isolation points are secure. Verify that locks are fitted correctly and tags are intact. Ensure the main switch or valve is in the off position. Before testing, notify all people in the immediate area that you are about to test the plant. This prevents anyone from interfering with the isolation or getting injured if the machine starts.

For electrical plant, use a rated voltage tester. The tester must be suitable for the voltage levels of the equipment. Test the tester on a known live source before and after you check the isolated plant. This proves the tester is working correctly. Test at the point of work, not just at the isolation switch. Check all phase conductors. The tester must show zero volts. If there is stored energy, such as in capacitors, discharge it safely according to the manufacturer instructions.

For mechanical or hydraulic plant, attempt to operate the controls. This includes start buttons, emergency stops, and remote controls. You must try to restart the machine using the normal operating procedures. The machine must not move or activate. If the plant has stored energy, like pneumatic pressure or raised weights, you must release or restrain that energy. You may need to manually cycle the machine to relieve pressure. Only do this if it is safe and you have the correct training.

If the test shows the plant is still energized or active, do not approach the machine. Return to the isolation point and investigate the fault. Do not proceed with work until the plant is completely isolated.

These steps help you meet your duties under the Work Health and Safety Act and the Work Health and Safety Regulations. Following this procedure aligns with AS 4024.1 Safeguarding of Machinery. Verification confirms the plant is safe for maintenance and cleaning. Never skip this step. A live test is the only way to be sure the isolation is effective.

Restoring Plant to Service

Restoring plant to service requires the same level of discipline and attention to detail as the initial isolation process. You must follow a strict sequence to ensure the safety of all personnel before the equipment restarts.

Clearing the Work Area

Before removing any locks or tags, the Supervisor or Responsible Person must inspect the entire work site. Check that all maintenance tasks are fully completed and all tools, spare parts, and temporary wiring have been removed. Do not leave items inside or near moving parts of the machine. Verify that all guards and safety barriers are reinstalled and secured. If the work involved a confined space, ensure all personnel have exited that space. You must physically account for every person who worked on the job. Only the person who applied the lock or the Supervisor may authorise the removal of safety devices.

Removing Lockout and Tagout Devices

Locks and tags must be removed in the specific reverse order to how they were applied. If a group lockout box was used, the Supervisor removes their lock last, after each individual worker has removed their personal lock. This confirms every person is clear of the machinery. Never remove a lock or tag applied by another person unless you have specific authorisation and strict verification that person is not present. Once locks are removed, operate the isolation points to the ON or OPEN position. Replace fuses or close circuit breakers if they were opened as part of the isolation.

Cleaning the Area

Clear the access ways and egress paths around the plant. Remove any debris, swarf, or oil spills resulting from the maintenance work. A clean workplace prevents slips and trips during the restart phase. Ensure any warning signs or barriers used to cordon off the maintenance zone are taken down. This signals to other workers that the area is returning to normal operations.

Safely Restarting the Machine

Before restarting, give a final warning. Use a designated signal such as a siren, horn, or verbal shout to alert everyone in the vicinity that the machine is about to start. Wait a few moments to ensure the area is clear. Stand at the control panel in a position where you can see the machine but remain out of the line of fire if any unexpected movement occurs. Energise the machine and observe the first cycle closely. Listen for unusual noises and check for vibrations or leaks. Do not leave the control station until the machine is running smoothly and consistently.

You must meet the requirements of the Work Health and Safety Act 2011 (WHS Act) and the Work Health and Safety Regulations (WHS Regulations) regarding the safe operation of plant. Following AS/NZS 4024.1 (Safety of Machinery) ensures your control measures are effective. Always document the return to service in the shift log or maintenance register.

Emergency Removal of Locks

In the event of an emergency where the removal of an isolation lock is necessary to prevent injury, damage to the plant, or a severe environmental incident, the Site Supervisor or the most senior person on site must authorise the immediate removal of the lock. This action overrides the standard tag-based system. The authorised person must attempt to contact the individual who applied the lock before taking action. If the installer cannot be contacted, the authorised person must verify that all energy sources are isolated to the extent reasonably practicable before removing the lock.

If the lock cannot be opened with the key, the authorised person may cut the lock using bolt cutters. Every effort must be made to avoid damaging the isolation point or the energy isolating device during this process. Once the lock is removed, the person removing it must immediately attach a Danger Tag to the isolation point. This tag must include the remover’s name, the date, and the time of removal. The original lock owner must be notified immediately after the situation is stabilised. They are not permitted to resume work on the plant until a new isolation risk assessment has been completed and fresh locks and tags have been applied.

Response to Incidents

If an incident occurs involving the plant, such as an unexpected start-up, energy release, or equipment failure, the immediate priority is safety. Any person in danger must move to a safe location. The emergency services must be contacted on 000 if there is a risk to life or health.

Following the immediate response, the Site Supervisor must shut down the plant completely using the nearest emergency stop button or valve. The area must be barricaded to prevent unauthorised access. No person should attempt to restart the plant or investigate the fault until isolation has been verified and the area is declared safe by a competent person.

The incident must be recorded in the site register and reported to the relevant health and safety regulator. Serious incidents, such as those requiring immediate hospital treatment or involving the release of a hazardous substance, are notifiable incidents under the Work Health and Safety Act 2011 (Cth) or corresponding state legislation. The site must be preserved for investigation purposes until an inspector directs otherwise. All workers involved in the incident or the emergency isolation process must undergo a debriefing and a review of this procedure before returning to work.