This section describes how to:

• identify and manage equipment hazards (for new and existing plant and structures)
• position and guard equipment
• use pre-start warning systems and emergency stop systems effectively
• prevent, detect and deal with fires and explosions
• manage electrical hazards
• manage specific hazards around lifting equipment, floating equipment and portable ladders
• safely work near highwalls or faces.

On this page

• 15.1 Scope
• 15.2 Existing plant and structures
• 15.3 Identification and risk assessment of plant and equipment hazards
• 15.4 Mechanical or electrical management plan
• 15.5 Choosing, buying and upgrading plant and structures
• 15.6 Positioning of plant and structures
• 15.7 Access routes
• 15.8 Guarding
• 15.9 Guarding and maintenance
• 15.10 Conveyors
• 15.11 Emergency stops
• 15.12 Pre-start warning systems
• 15.13 Electricity

15.1 Scope

HSWA defines ‘plant’ as including any machinery, vehicle, vessel, equipment, appliance, container, implement or tool, as well as any component of those things or anything fitted to those things. ‘Structure’ is defined as anything that is constructed, whether fixed, moveable, temporary or permanent – including buildings, masts, towers, frameworks, pipelines, bridges, quarries, shafts or tunnels – as well as any component or part of a structure.

On extractives sites, this scope of plant and structure covers almost any equipment used at work including:

• hand tools such as hammers and handsaws
• individual machines such as circular saws or trucks
• apparatus such as laboratory apparatus (for example, density meter)
• lifting equipment such as hoists, forklifts, elevating work platforms or lifting slings
• other equipment such as ladders, pressure water cleaners
• installations such as crushing plant and associated conveyor systems, buildings, material bins and walkway structures.

This section covers plant and structures commonly used at extractives sites, where the information in supporting documents, such as other WorkSafe guides, may not be sufficient to provide industry specific guidance.

15.2 Existing plant and structures

You need to know what the hazards are with your plant and structures, so you can address those hazards. The first step in the hazard management process is to identify hazards – anything that can injure or harm someone. To identify hazards, it is useful to first identify all plant and structures at your site.

Do a workplace inspection to identify all plant and structures. Include common items that may not usually be thought of as ‘plant’. Also consider how other workplace items such as steps or platforms can affect the use of your plant and structures.

Once you have identified all plant and structures, you can identify their hazards.

With changes in technology and cost of solutions over time, measures to eliminate or isolate a hazard may become practicable. You should continue to assess significant hazards to determine whether there are other methods to control them. For example, replace a plant with newer plant that eliminates the hazard. You should also routinely review systems, procedures and standards to reflect changes in technology and best practice. For example, reviewing industry safety alerts and insights from incidents relating to plant and structures and other extractives sites.

15.3 Identification and risk assessment of plant and structure hazards

Identify hazards using physical inspection, task analysis, process analysis, risk assessment process, guidance and standards, hazard and operability analysis (HAZOP) and accident investigation analysis. You must engage with your workers in the identification of hazards.

When identifying hazards associated with plant and structures and undertaking a risk assessment, consider:

• how plant and structures might feasibly fail, and the likely consequences of any such failure (for example, structural support collapse)
• the type of fuel or energy used to power plant, equipment or installations used at the site (such as electricity, gas or petroleum)
• what the possible consequences of a loss of control situation would be (such as mechanical failure leading to uncontrolled release of hazardous substances or energy sources)
• the hazards relating to moving parts (such as draw-in hazards, nip-points, entanglement hazards)
• the hazards relating to suspended parts
• the hazards relating to surfaces (very hot or very cold).

For more detailed information on identifying, assessing and controlling hazards, and on assessing and managing risks, see Section 2 of this guide, along with our Safe use of Machinery Best Practice Guidelines

If the likelihood or consequence of the risk posed by a hazard is not clear, seek the advice of a specialist mechanic, designer, engineer or the machinery or equipment’s original manufacturer.

15.4 Mechanical or electrical management plan

When developing a management plan for mechanical hazards, do a risk assessment and consider:

• the standards of engineering practice to be followed throughout the life cycle of the mechanical plant and installations
• the safe operation of conveyors, winding systems, mobile plant and dredges
• the safety of plant and installations
• rollover, falling object and cabin intrusion protection
• seatbelts and other restraints
• protective canopies
• safe storage and use of pressurised fluids
• means for the prevention, detection and suppression of fire on mobile plant and conveyors.

When developing a management plan for electrical hazards, do a risk assessment and consider:

• prevention of harm from electrical sources
• prevention of fires being started by electricity
• prevention of unintentional starting of electrical plant
• fitting electrical safeguards
• competencies required for workers carrying out electrical work
• the reliability of plant and installations used in monitoring hazard control measures and communication systems
• a maintenance management system
• safe work practices for working on high voltage installations
• any other requirements of the MOQO Regulations in relation to the safety management of electrical plant and installations and electrical engineering practices
• the requirements of regulations made under the Electricity Act 1992.

The Electricity (Safety) Regulations 2010 contain specific requirements for extractives sites, including:

• mobile and relocatable mining electrical equipment used at extractives sites
• work on or near bare live conductors
• record keeping and plans
• prescribed electrical work.

Develop the plans and procedures for mechanical and electrical hazards in the context of the whole health and safety management system. They should not be developed in isolation from other plans, processes and procedures that rely on the control. This will ensure gaps and overlaps in information and procedures are identified and used in the implementation of suitable control measures to minimise the likelihood of potential risks and impacts.

15.5 Choosing, buying and upgrading plant and structures

The most efficient and cost-effective time to ensure plant and structures are safe is when they are being scoped, designed and purchased. All operators should specify their expectations for achieving safety standards.

The designer, manufacturer, supplier and employer have obligations under HSWA and the MOQO Regulations and should work together to manage aspects such as:

• how the plant and structures are used in the workplace
• risk levels and standards required
• type of guarding based on work activity
• who will provide, install and commission the plant or structures
• integration with other plant or structures
• the working environment in which the plant or structures will operate
• any hazardous exposures arising from use of the plant or structures, such as noise or fumes
• who will train and supervise the operators
• operations and maintenance procedures
• intrusive maintenance and internal inspections required
• potential blockages or unusual situations
• how isolation from hazardous energy can be achieved.

Where the plant or structures are being designed and manufactured in-house, you take on the responsibilities set out in HSWA sections 39 and 40. As the designer you must have health and safety, including relevant standards, in mind when developing design concepts and throughout the design process.

If newly purchased plant or structures are not safe because of the way they have been designed, constructed, supplied or installed, you should stop using them until this has been fixed. Contact the manufacturer or supplier (or installer if relating to the installation) to resolve the issue.

For more information about overlapping duties, see Appendix E, and for upstream duties relating to the supply chain, see Appendix G.

15.6 Positioning of plant and structures

As a general rule, activities such as crushing and screening are noisy and dusty, so they are positioned away from boundaries to lessen the nuisance of the activities. Some noisy and dusty processes may need to be housed to control these effects.

The safety of workers in the processing area is paramount. Traffic should be routed around the plant and structures wherever possible, and plant and structures should be sited away from hazards such as unstable ground (for example, rock falls, ground settlement or historic underground workings) or overhead power lines.

Services, including electricity, air and water should be included in a site layout plan, particularly when placed underground. 

15.7 Access routes

Plant and structures, including mobile crushers, often have areas where access at height is required to carry out routine operations, undertake maintenance or access control rooms.

For structures defined as buildings under the Building Act 2004, the Building Code specifies you must provide reasonable and adequate access to enable safe and easy movement of people. When planning, designing and constructing access routes, you must also consider your obligations under HSWA and the MOQO Regulations.

For the design, construction and installation of platforms, walkways, stairways and ladders on extractives sites, the standard NZS/AS 1657 Fixed platforms, walkways, stairways and ladders sets out specific requirements.

The site’s traffic management plan should provide for safe means of transport for worker’s access to their place of work within the operation.

15.8 Guarding

Where elimination of a hazard is not reasonably practicable, guarding is an effective isolation control provided the guards are the correct ones, and they remain in place.

The fundamental principles of guarding machinery are covered in our Safe Use of Machinery Best Practice Guidelines, and Ergonomics of Machine Guarding Guide.

This section provides additional guidance on effective guarding on fixed and mobile processing plant typically found in quarries and mines. It is not intended to be a comprehensive list, and you may determine other types of guarding are more suited to the circumstances at your site.

Perimeter fencing (or area guards), although commonly used at extractives sites, does not meet the minimum requirements of the standard AS/NZ 4024.1 Safety of machinery when workers require access within the perimeter while the machinery is running. In these situations, fixed guards should be used to guard individual nip-points and entanglement hazards.

Extractives sites should assess their plant and reference what type of guarding is required by AS/NZ 4024 (for example fixed guarding or interlocked guards).

See Figures 81 to 90 for examples of fixed guards.

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Fines dewaterers use slowly rotating scraper blades to extract the finer particles. In addition to a sheet metal guard on the main dewatering section, a mesh guard should be provided around the trough of the scraper blade section. This should be fitted high enough to avoid workers falling into the trough or being able to reach the scraper blades and be at least 2.7m above ground level.

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Panel type guards secured to fixed uprights may be suitable for large rotating cylinders such as screens, dryers and trommels. The minimum height of the guard should be 2.7m. Access gates should be interlocked unless access is required less than once per shift, in which case a fastened gate can be used (must require a tool to open).

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Batch feeder belts, while generally slower, have the same hazards as a normal conveyor. The feeder and all associated nip-points should be enclosed within suitable guards fitted along the full length of the feeder. Guards should be provided on the underside to prevent access to tail and head drums.

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Vee-belt drives are commonly used on various items of plant. Open mesh guards help with efficient cooling of the vee-belts and pulleys and allow vee-belt tension to be visually checked without removal of the guard. The guard should fully enclose the front and back as required to prevent access.

As with vee-belt drives, a fixed guard totally enclosing the drive is suitable for primary jaw crusher drives. Alternatively, guarding fitted around existing structures may be suitable.

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Steel grids, with sufficient strength to withstand any anticipated loads, should be provided in the top of all ground feed hoppers and easily accessible elevated feed hoppers. This is to prevent unauthorised or inadvertent entry. The exception is with primary hoppers or where products of a large dimension are being processed which may obstruct the grid.

Fitting grids on elevated hoppers may encourage people to walk on them next to an unprotected edge. Appropriate access prevention measures should be incorporated in the design (such as barriers).

Provision should be made to enable drivers at ground feed hoppers to release tail gate latches from a position of safety.

Conveyor guarding

Most serious accidents and fatalities with conveyors result from the machinery, and associated in-running nip-points, not being adequately guarded.

A wide variety of mechanical motions and actions on a conveyor system will present hazards to the worker. These can include the movement of rotating parts, moving belts, meshing gears and any parts that impact or shear. These different types of hazardous mechanical motions and actions are basic in varying combinations to nearly all machines. Recognising them is the first step toward protecting workers from the hazards they present.

On a conveyor, in-running nip-points are dangerous trapping points at the line of contact between the rotating drum or pulley (cylinders) and the moving conveyor belt on the in-running side of the cylinder. A similar point on the out- running side of the cylinder where the conveyor belt exits is not a dangerous location unless the conveyor can be reversed.

Even smooth, slowly rotating cylinders can grip clothing, and can, through skin contact alone, force an arm, hand or body into a dangerous position. Often the machine is running too fast or is too powerful to allow the person to stop the machine or pull the body part out. This can result in severe friction burns, amputation or significant (including fatal) crushing injuries.

Where a moving part cannot reasonably practicably be eliminated, and workers are exposed to potential contact, fitting fixed barrier guards and additional in-running nip guards are practicable isolation control measures.

Hazardous trap points may occur at a variety of locations, including:

• power transmission moving parts
• head and tail end pulleys
• bend, snub and take-up pulleys
• carrying and return idlers beneath feed hoppers, skirt plates and where the lift of the belt has been restricted as well as at convex curves (brow position)
• roller assemblies for conveyor belt tracking
• idlers accessible to people such as from crossovers or underpasses, maintenance or storage areas or cleaning areas and transition idlers adjacent to pulleys
• drive drums.

The following pages outline possible guarding for conveyor belt parts in operation, including:

• power transmission moving parts
• belts
• upper and lower strands in a straight run
• curved zone (brow positions)
• head and tail drums and transition zones
• gravity take up units
• fixed obstacles
• skirt boards.

It also provides general information on the use of nip guards. 

POWER TRANSMISSION MOVING PARTS

Hazards associated with power transmission moving parts include the drive shaft, shaft end, sprocket, pulley, chain, drive belt and gear coupling. Possible consequences include drawing-in and crushing, as well as entanglement of a loose piece of clothing in a protruding moving part.

If a hazard is less than 2.7m from the ground, working platform or any other location (for example, stockpiles), fixed barrier guards should be fitted. 

BELT

If the belt is in good condition, possible consequences of contact (depending on the speed and belt characteristics) include friction burns or abrasion and impact with the belt.

Install hazard control measures in accordance with the results of your risk assessment.

If the belt is not in good condition, or there is evidence of a damaged belt splice, drawing-in, burns and lacerations may be possible. Change the belt splice design or manufacturer if this is an ongoing problem. Otherwise maintain the belt and belt splice according to the manufacturer’s specifications. 

UPPER AND LOWER STRANDS IN A STRAIGHT RUN

An in-running nip will be present between:

• the upper strand and the pulleys under the hopper
• the upper strand and the pulleys under the skirt-board or skirt
• the upper strand and support rollers
• the upper strand and return rollers
• the lower strand and scrapers.

The following figures show suggested guarding in these areas.

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CURVED ZONE (BROW POSITIONS)

In-running nips will be present between the belt and rollers in the curved zone with a possible drawing-in consequence. Fit a fixed barrier guard and, where required, additional nip-point guards. 

HEAD AND TAIL DRUMS AND TRANSITION ZONE

In-running nips with a possible drawing-in hazard are present:

• between the belt and drums
• at the junction between two conveyors
• between the drum and fixed support brackets
• between the upper strand and the load carrying rollers in the transition zone.

Entanglement hazards also exist where the shaft is exposed. A fixed barrier guard and additional nip-point guards should be fitted.

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Head drums, which may become accessible by climbing stockpiles, should be guarded. Alternatively, stockpile heights should be strictly maintained to below 2.7m in accordance with the reach distances specified in the standard AS/NZ 4024.1 Safety of machinery.

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GRAVITY TAKE-UP UNITS

Conveyor gravity take-up units should be enclosed with mesh panels which prevent access to moving parts within the structure. This prevents the risk of the gravity take-up weight falling to ground level in the event of the belt, chains or ropes breaking. All panels should be secured so they require a tool for removal, or should be interlocked.

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FIXED OBSTACLES

Fixed obstacles which are not part of the conveyor can result in a person being trapped between the load and the fixed object. Examples of fixed objects are:

• posts
• walls
• tunnel entrances
• associated fixed equipment (such as metal detectors)
• large bulk loads (such as boulders).

In relation to your risk assessment results, consider fixed guards and deterrent devices. The objective is to keep the body, arms and legs away from the crushing area. The type of guard and its dimensions will depend on the body part at risk of being trapped and the weight of the load. Ensure that the guard itself does not create a drawing-in or trapping area.

SKIRT BOARDS

The MOQO Regulations specify that you must ensure conveyors are designed, installed and used in such a way that no one is struck by falling objects. The use of skirt boards can limit the amount of material that falls from conveyors (see Figure 96).

Install skirt boards or other protective devices at:

• loading and transfer It is recommended that the skirt boards be at least two and a half times longer than the belt is wide, to allow the material to ‘settle down’
• areas that have unusual features, such as magnets, crushers and grizzlies
• places where people pass under the belt
• areas where maintenance, clean-up or inspection activities are frequently performed.

In situations where fixed skirts are fitted above conveyor idlers, a trap point exists between the idler and the belt. Panels of guards should be fitted to prevent access to the trap points associated with the skirts of the conveyor (see Figure 96).

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General information on the use of nip guards

Nip guards prevent access to the in-running nip’s drawing-in zone. Where practicable, the nip guards should fill the drawing-in zone as much as possible and should be sufficiently rigid not to increase the clearance between the guard and the cylinders or the belt.

However, nip guards do not protect against the risk of pinching between the guard and the cylinder or belt, so residual risks of abrasion or burns may remain.

They also do not provide appropriate protection against the risks of hair or clothing being drawn in. Therefore, the risk assessment should take into account that the drawing-in effect increases with the diameter of the rollers, their roughness, their rotational velocity and the clothing or PPE worn (for example, gloves).

To limit the risks of pinching, abrasion and burns, the clearance between the nip guard and the cylinder or belt should be as small as possible (maximum 4mm). The angle between the guard and the tangent to the cylinder or between the guard and the belt should be 90° or slightly larger.

Nip guards are particularly suitable for cylinders, drums and rollers with a smooth and full end disc. They can be used with a smooth, flat or troughed belt, if they follow the profile of the belt and the belt is tight and does not vibrate.

Where there are other machine hazards that require guarding (for example, head drums with exposed rotating shafts), nip guards should be used in addition to fixed or inter-locked barrier guards.

When designing nip guards, consider the type of product and the moisture of the product being processed, as well as appropriate belt cleaning devices such as belt scrapers.

Drawing-in zones

All in-running nips create hazardous zones (also called drawing-in zones) between the cylinder and the belt, or between two cylinders. In the case of a cylinder in contact with a belt, the drawing-in zone has the shape of a triangle that becomes even more acute when the cylinder radius is large. The zones vary in depth in relation to:

• the diameter of the cylinders
• the gap between the cylinders
• the gap between the cylinder and the stationary object.

To calculate the dimensions of these drawing-in zones for design purposes, see the relevant parts of the following standards:

• AS/NZS 3610: 2015 Safety of Machinery Part 3610: Conveyors – General Requirements and Part 3611: Conveyors - Belt conveyors for bulk materials handling
• ASNZS-4024-36142015 Safety of machinery - Part 3614: Conveyors – Mobile and transportable conveyors
• ASNZS-4024-36122015 Safety of machinery - Part 3612: Conveyors – Chain conveyors and unit handling conveyors
• ASNZS-ISO-4024-16012024 Safety of machinery, Part 1601: Guards – General requirements for the design and construction of fixed and movable guards. 

Idler roller nip hazards on heavy duty belt conveyors

There is also a significant risk of injury posed by nip-point force on heavy-duty conveyor top and bottom idler rollers and the generally increased accessibility of nip-points due to greater width of idler rollers (particularly bottom idler rollers).

The two main factors to consider when undertaking a risk assessment are:

• The degree of hazard (likely severity of injury): Determined largely by the pressure between the belt and the idler For example, if the stationary conveyor belt cannot be lifted off the idler by a person using one hand, it is likely nip guards will need to be installed.
• The likelihood of access to the nip-point: Determined by the height of the nip in relation to the activities that could be performed at that location and the separating distance between the nip-point and the likely position of workers that might make contact with it.

Where belts are running at high speed, the risk increases as well, and consideration should be given to fitting nip guards.

Secondary in-running nip guards

Sometimes access is needed behind barrier guards or fixed guards, for the purpose of maintenance and cleaning of conveyor systems. This results in potential exposure of workers to nip-points. In addition, guards are often left off at positions where they have to be frequently removed.

Fitting a secondary in-running nip guard provides protection to workers when the primary guard is removed.

Previous initiatives have involved emergency stop cables interlinked with guards. However, as these are not as effective as nip guards fitting directly at nip-points (in addition to any other guards required) WorkSafe recommends fitting nip guards at nip-points, where practicable.

Consider putting additional control measures in place when performing maintenance, or during commissioning activities. A risk assessment will help determine suitable control measures.

Maintaining nip guards

Nip guards are essential safety devices and must be maintained in effective working order. They should undergo a suitable scheme of inspection, examination and maintenance. Each nip guard should be individually identified in such a scheme to ensure its location is known and each has its own record of inspection, examination and maintenance.

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Stone guillotine guarding

Stone guillotines (or stone cutters) with unguarded cutting knives can cause amputations and other serious injuries.

Examples of machine guarding methods include barrier guards, two-handed starting devices, remote-operator controls and electronic safety devices (such as light curtains).

Using machine-guarding methods that eliminate worker access to the cutting knife (called the ‘point of operation’) is the preferred method of hazard control (see Figure 99).

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Two-handed starting devices are a cycle-initiation method that requires constant, simultaneous pressure from each hand on two separate controls to move the cutting knife. If the operator removes either hand from either of the controls, the blades will stop immediately. Two-handed starting devices are essential where fixed guards are not practicable (for example, where the operator needs to feed blocks of stone into the cutting area), and operating controls are close to the knife.

A suitable guard should be fitted to the side of the guillotine opposite to the controls where workers may reach into the hazardous area. Guillotines which rely on someone picking or pushing the stone after being cut should be fitted with a drop side or conveyor. This is so the stone is fed away from the hazardous area. Alternatively, a suitable tool should be provided (see Figure 100).

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Stone saw guarding

Stone saws range from sophisticated equipment capable of cutting large slabs of stone and intricate designs to smaller machines capable of simple cuts. Regardless of the size of the saw an operator may be close to the hazardous area when operating and suitable guarding or control measures should be in place.

For larger saws the use of perimeter fences and interlocked gates would prevent inadvertent access and prevent the operator from working too closely to the equipment.

Fixed guards alone might not be feasible as access is required for loading and unloading the stone. The following would all offer a high standard of protection:

A perimeter fence and interlocked guards, such as manually-actuated sliding access gates (see Figure 101). The interlocked guards should be fitted with a locking device, so the guard remains closed and locked until any risk of injury from the hazardous machine has passed. This should allow for the rundown time of the saw blade.

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Electro-sensitive protective equipment such as light curtains at the front of the enclosure. When used in conjunction with a braking system to stop the movement before access to dangerous parts occurs. Alternatively, the saw head could immediately return to a home position with a local guarding enclosure (see Figure 102).

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Local retracting guards around the circular saw blade and pressure sensitive edges on the saw head and traversing table. This would be in conjunction with fast stopping times of the head and saw blade.

Guards may be extended to serve as noise enclosures. Local exhaust ventilation systems may be integrated with the guard where appropriate.

Fixed guards or two-handed operator controls such as those outlined for stone guillotines may be suitable for smaller saws.

Remote-operator controls force the operator to remain at a safe distance from the hazard point (see Figure 103). Hold-to-run controls should be used for remote-operator controls. The machine should run down in the time it would take someone to reach the hazardous area when the operator removes their finger or hand from the control. Suitable controls should be in place to stop anyone else entering the hazardous area.

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15.9 Guarding and maintenance

Where maintenance requires normal guarding to be removed, then additional measures will be needed to prevent danger from the mechanical, electrical and other hazards that may be exposed. This is also necessary if access is required inside existing guards. There should be clear company rules on what isolation procedures are required, and in what circumstances. For example, some cleaning of mixing machinery may require isolation, even though it might not be considered a maintenance task.

Tensioning, tracking, lubrication and other maintenance is usually done while equipment is running. To eliminate the risk of injury, rods and nuts should protrude out beyond the guards. Consider grouping the lubrication points for access outside the guards (see Figure 104). Consideration should be given to this when designing plant.

Consider manual handling when removing guards for maintenance to be carried out. Lifting attachments on guards may be required.

For more detailed information on lockout and tagout for maintenance and repairs, see Section 15.17.

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15.10 Conveyors

Anti-run back device and controlled braking

Some inclined conveyors have the potential to either run back (where the direction of the material is up) or run away (where the direction of the material is down). These situations can be prevented by installing an anti-run back device (or sprag clutch) and controlled braking systems.

Standards for safety of machinery can add more information on anti-run back devices and controlled braking systems. See AS/NZS 4024 Safety of Machinery – Part 3610: Conveyors – General Requirements or AS/NZS 4024 Safety of Machinery – Part 3611: Conveyors – Belt Conveyors for Bulk Materials Handling.

Conveyor crossovers and underpasses

As well as the guarding requirements outlined in Section 15.8, you must provide safe crossing points where a conveyor may be crossed. Crossing over or under conveyors should be prohibited except where safe passageways are provided.

Access routes must maintain a minimum of 2.1m clearance overhead (as defined in the NZ Building Code – Clause D1: Access Routes). However, where people can reach into moving parts the clearance overhead should be a minimum of 2.7m in accordance with AS/NZS 4024.1 Safety of machinery.

The MOQO Regulations specify that an extractives operator must ensure any conveyor belts are:

• designed, installed and used in a way that will address any hazard that may arise when the conveyor belt is started
• fitted with an emergency stop system that can be activated at any point along the length of the conveyor belt accessible by any person
• designed, installed and used to protect any person near or travelling under a conveyor belt from being struck by fallen objects
• designed, installed and used to address the hazards arising from the interaction between people and the conveyor This must include provision for the safe crossing of conveyor belts, where they may be crossed.

Whenever conveyors pass adjacent to, or over, work areas, roadways or other passageways, protective guards should be installed. The guards should be designed to catch and hold any load or material that may fall off or become dislodged from the conveyor (for more information on conveyor skirt boards see Section 15.8).

Where conveyors are operated in tunnels, pits and similar enclosures, ample room should be provided to allow safe access and operating space for all workers.

Pre-start warnings on conveyor belts

Pre-start warnings must be provided on conveyor belts to address any hazard when they are started.

On overland conveyor systems, the devices should be placed at the transfer, loading, and discharge points and those points where workers are normally stationed. Warning signs stating ‘conveyor may start without warning’ should be strategically placed along overland conveyors where it is reasonably foreseeable that people may gain access.

For more information on pre-start warning systems see Section 15.12.

Reclaim tunnels

The nature of reclaim tunnel operations means the presence of people in the tunnel is normally only required on an infrequent and irregular basis. Loading operations are usually remotely activated and control room operators may not expect workers to be in the reclaim tunnel which can lead to hazardous situations. Workers should only enter the reclaim tunnel to inspect, clean or maintain the system when effective safe systems of work are in place.

Reclaim tunnels may be a confined space entry (see Section 15.16).

15.11 Emergency stops

Emergency stops, including pull wire emergency stops, should not be used as a substitute for guards. They are an additional control measure. Emergency stops should be in red with a yellow background, where practical, and signs should be erected for easy identification (see Figure 105).

Do not use emergency stops to lock-out the plant or equipment because the actuators are part of the control circuit and not an isolation of the energy supply.

Emergency stops should:

• be prominent, clearly and durably marked
• be immediately accessible to each user of the plant or equipment
• have red handles, bars, push buttons or pull cords (labels can also be used)
• not be affected by electrical or electronic circuit failure.

Mine operators must fit an emergency stop system that can be activated at any accessible point along the length of a conveyor belt.

For more detailed information on emergency stop controls see our best practice guidelines Safe Use of Machinery (Section 8.1.7 of that guide) and for design refer to AS/NZS 4024 Safety of Machinery: Part 1604: Design of controls, interlocks and guarding – Emergency stop – Principles for design.

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15.12 Pre-start warning systems

Pre-start warning systems are mandatory on conveyors. For other plant, pre-start warning systems should be provided on machinery where sudden, unexpected operation could cause serious or fatal injuries to those who may be close to the machinery. Consider systems with visual, acoustic and tactile signals.

Because mines and quarry processing areas can be noisy and spread out, consider both visual and acoustic prestart warnings that work in conjunction with one another.

Acoustic signals should:

• sound for long enough before the plant or equipment starts to provide adequate warning to anyone who may be in a position of risk
• loud enough so they can be heard in the area they are providing a warning for
• be at a level higher than the ambient noise without being excessive or painful
• be clearly different from any other warning signals or alarms.

Visual signals (such as flashing lights) should be placed so people close to the plant or equipment will have the best opportunity to see it. You may need multiple visual signals depending on the set-up of your plant and whether an acoustic signal will be sufficient to provide warning. Where visual signals are used, they should be of a suitable brightness and colour contrast to the background.

For more detailed information on acoustic and visual signals refer to AS/NZS 4024 Part 1904: Design, controls, actuators and signals – Indication, marking and actuation.

15.13 Electricity

The Electricity (Safety) Regulations 2010:

• state the generic rules and requirements about electrical safety and what is deemed to be electrically safe and unsafe
• deal with the design, construction and use of works, installations, fittings and appliances
• provide for installations to be designed and installed under AS/NZS 3007 Electrical equipment in mines and quarries – Surface installations and associated processing plant
  • define certification and documentation required for all electrical works
  • state requirements for periodic assessment and verification of electrical safety
  • set out in schedules all the applicable standards, with a focus on the adoption of international standards
  • define requirements relating to safety management systems
  • provide for offences including infringement offences.

The Electricity (Safety) Regulations 2010 places requirements on the owners of mining electrical equipment to ensure it is electrically safe. The Regulations state the standards to use for certain installations, along with periodic assessment requirements for mobile and relocatable mining electrical equipment.

One particularly important document is AS/NZS 3007:2013 Electrical equipment in mines and quarries – Surface installations and associated processing plant. You should make sure all electricians working on your site are familiar with this standard.

Mobile and relocatable equipment at alluvial mines and quarries must be assessed at least yearly against AS/NZS 3007 by a person authorised to inspect mining electrical equipment in accordance with the Regulation 78D of the Electrical (Safety) Regulations 2010.

As a general approach, you should:

• use residual current devices (RCDs)
• ensure equipment is correctly earthed
• electrical substations should be kept clean and not used as They should be kept locked with access to authorised workers only
• all equipment, including electrical supply and accessories, should be part of the electrical maintenance and inspection scheme
• batteries should be treated with Manufacturers’ instructions should be followed for maintenance and precautions to be taken (for example, PPE)
• dust accumulations can have a serious effect on the safe functioning of electrical Make sure housekeeping procedures are in place
• all electrically powered equipment should be capable of being The isolation points should be clearly labelled and means of isolation provided
• operators should not have access to switchboards or enclosures that provide direct contact to an electrical Access to certain electrical equipment should be restricted with the use of a tool or key, and should be properly shrouded to prevent inadvertent access to exposed electrical conductors
• where the operators have been properly trained it may be appropriate to access some electrical equipment for the purposes of resetting In these cases it may be permissible to open cabinet doors provided the equipment inside is properly shrouded to prevent inadvertent access or arc flash
• switchboards should be securely locked at all Where wiring is damaged it should be reported immediately. Water should not be allowed to accumulate in switch boards or switch rooms
• underground cables and pipes should be accurately located on a site plan and identified before digging.

For more detailed information on safety around underground cables and pipes see our good practice guidelines Excavation safety

Flexible cords

Flexible cords should have a current tag issued in accordance with AS/NZS 3760:2022 In-service safety inspection and testing of electrical equipment and RCDs. Minimum information a test tag should have is:

• a reference to being tested to AS/NZ 3760
• the test date
• the next test date due.

A flexible cable or cord (for supply purposes) is one that has one end connected to a plug with pins designed to engage with a socket outlet and the other end either:

• connected to terminals within the equipment, or
• fitted with a connector designed to engage with an appliance inlet fitted to the equipment.

Flexible cords are prone to damage because they are often outdoors in operational areas and can be subject to falling material, repetitive use, movement, vibration and extremes of weather. Regardless of the date of the tag, all flexible cords should be examined before being plugged in and used. Consider any shock or tingle as a warning of a potential safety problem. If this occurs, immediately switch off, isolate and remove the cable and do not use it again until tested by a competent electrician.

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Trailing cables

Safe systems of working with trailing cables should include meeting the New Zealand Electricity (Safety) Regulations 2010 and AS/NZS 3007 Electrical equipment in mines and quarries – Surface installations and associated processing plant.

These safe systems of working with trailing cables should also include:

• regular inspections including in-situ visual inspection by machine operators and regular documented safety assessments (at least annually) with documentation kept in a verification dossier for the equipment onsite
• route criteria including support measures (where applicable), methods and heights for crossings, location of cables in proximity to roadways, protection measures required where it is necessary for vehicle crossings
• methods for relocation of cables and provision of adequate equipment to perform the task such as cable reelers or relocators
• defined methods for manual handling and provision of adequate mechanical lifting aids to eliminate manual handling sprains and Equipment to separate and join plugs should be sought
• regular inspection, maintenance and testing performed on substation earth systems including earth mats, earth impedance and earth connection points, protection relays and trip batteries
• provision of unique clear identifiers for each cable and trailing cable plug and substation outlet
• defined standards for the circumstances under which trailing cable protection relays can be reset and power re-energised onto a cable where the relay has indicated a fault to be present
• developing, implementing, monitoring and reviewed systems of high voltage switching, access and authorisation
• minimising direct handling of energised Anyone required to directly handle energised trailing cables should wear insulating gloves covered by leather outer.

Training should be provided in the above and in trailing cable hazard awareness for all people required to work with them. Workers associated with relevant tasks should be consulted in relation to the development of the systems and standards mentioned above.

15.14 Cranes and lifting equipment

Where there is a crane on site, you must comply with the Health and Safety in Employment (Pressure Equipment, Cranes and Passenger Ropeways) Regulations 1999 and should comply with the Approved Code of Practice for Cranes

Fixed cranes include gantry cranes, overhead hoists, monorail systems, davit arms or fixed lifting points. The structures supporting the crane should be certified by a chartered professional engineer with respect to design, construction and non- destructive testing, as relevant.

The issued structure certificate should specify:

• design standards referenced
• maximum permissible safe working load and any load limitations or conditions
• details of equipment that may be used on the certified structure (Note: Some equipment is exempt from this Refer to the Notice of Exemption for Equipment under the Health and Safety in Employment (Pressure Equipment, Cranes, and Passenger Ropeways) Regulations 1999, New Zealand Gazette, No 188, page 4517, 17 December 2009).

Items of mobile plant, not originally designed as a crane used for load-lifting incidental to their principal function are exempt from the Health and Safety in Employment (Pressure Equipment, Cranes, and Passenger Ropeways) Regulations 1999 (Notice of Exemption for Equipment under the Health and Safety in Employment (Pressure Equipment, Cranes, and Passenger Ropeways) Regulations 1999, New Zealand Gazette, 24 September 2015) when the following conditions apply:

• Lifting points and equipment used for rigging loads are to be certified by a Chartered Professional Engineer, and
• In the case of hydraulic excavators with an operating weight of 12t or more the following additional conditions apply:
  • The equipment is not to be modified to make it operate as a crane other than the provision of a lifting point.
  • Hose burst protection valves are required.
  • Operators and ground support personnel are to be adequately trained as required by HSWA.
  • Operations are to be carried out in accordance with the Approved Code of Practice for Load-lifting – Rigging.
  • The equipment is to have a loading chart available to operators.

Sites using mobile plant for lifting should consider:

• planning for lifts with a lift plan completed by a suitably qualified operator, taking into consideration the rigging equipment and the full weight to be lifted
• using a dogman
• the orientation of the lifting plant in relation to the load
• assessing that the ground will take the loading of the excavator or other lifting plant
• checking that the ground loading does not create surcharges to trenches or batters
• using suitable lifting points (a strop slung over a fork on a forklift is not suitable).

All sites should develop a safe system of work for the use and management of all lifting equipment in accordance with the Approved Code of Practice for Load-lifting Rigging

This includes, but is not limited to:

• making sure every lifting appliance and item of loose gear is clearly and permanently marked with its ‘working load limit’ (WLL) by stamping, or where this is impracticable or not recommended, by other suitable Also, a unique identifying numbering system to clearly identify individual items should be used
• visual inspection prior to and after use
• examination by a competent person regularly depending on frequency, use, and environmental conditions but not exceeding 12 months
• a register should be kept for lifting The register should show the date of the last recorded examination or test, and any alterations.

15.15 Maintenance of plant and structures

Tasks such as maintenance, repairs, servicing, clearing blockages and cleaning can be dangerous. Workers can be fatally or seriously injured if they do not manage the risks carefully.

You should establish a maintenance and inspection programme to ensure equipment and machinery is safe to use. Maintenance and inspection programmes should take into account:

• the operational environment the machinery or vehicles are being used in, particularly where subject to corrosion or rot
• the original equipment manufacturer’s recommendations.

Maintenance and inspection programmes should take into account the whole of the machinery or vehicles including, as appropriate, including:

• the structure of the machinery (bracing or supports)
• safety features (such as emergency stops, guarding, emergency equipment or props)
• integrity of walkways, stairs, ladders, railings or guardrails
• integrity of holding vessels (for example, tanks or hoppers)
• integrity of lifting equipment (for example, chains, strops, hooks, gantry cranes, lifting eyes or quick hitches)
• signage and other warning devices (such as lights or alarms).

All extractives operators must ensure a competent person examines any mobile plant that has been stopped for the preceding 24 hours or longer before it is started. In addition, the extractives operator must ensure a competent person examines every accessible area of the operation.

Inspect every area containing barriers, machinery and surface infrastructure at least weekly and every area where a worker, is or will be, before every shift and during shifts as required.

A written procedure must be included in the health and safety management system setting out:

• what will be examined
• when it will be examined
• how findings will be recorded
• how findings will be actioned.

For more detailed information on inspection and maintenance of machinery, including safe systems of work, see our best practice guidelines Safe use of Machinery

15.16 Common hazards when undertaking maintenance

Undertaking maintenance activities (including cleaning) can potentially expose workers (and others) to significant hazards. The hazards outlined in the following chapters merit particular attention:

Falls from height

Maintenance work often involves using access equipment to reach raised sections of machinery or vehicles. Eliminating the need to access machinery or vehicles at height by careful design is the most effective control.

Where elimination is not practicable, and frequent access is required, then platforms, walkways, stairways and ladders that comply with the Building Code should be provided. Where infrequent access is required, suitable temporary access equipment with adequate barriers or fall restraint systems should be used.

For more detailed information on platforms, walkways, stairways and ladders see the Compliance Document for New Zealand Building Code Clause D1 Access Routes and Compliance Document for New Zealand Building Code Clause F4 Safety from Falling.

More information on the hazards of working at height can be found in our Best practice guidelines for working at height in New Zealand

Portable ladders

Portable ladders should be used for low-risk and short-duration tasks. The user should maintain three points of contact with a ladder or stepladder to reduce the likelihood of slipping and falling. Ladders and stepladders do not offer fall protection and should therefore be the last form of work access equipment you consider.

Portable ladders should comply with AS/NZS 1892.1 Portable ladders – Metal or any other standard embodying the same or more stringent criteria.

All portable ladders should have their safe working load certified by the manufacturer and be inspected for any damage prior to every use.

For more information on ladders and stepladders see our Best Practice Guidelines for Working at Height in New Zealand

Falls of heavy items

Heavy items sometimes have to be moved, or get disturbed, during maintenance work. If one of these falls, the results can be fatal.

Incidents can include:

• the failure of lifting equipment
• inappropriate lifting and slinging practices
• inadequate supports or supports not resting on level or firm ground
• incorrectly estimating the weight or centre of gravity of the load
• rocks falling from trap points on mobile plant or the headboards of haul trucks.

If a heavy item has to be moved or temporarily supported during maintenance work, it is crucial to assess the risks and properly think through a plan of action. The people responsible for the maintenance work should not presume that things will be okay, that others will know what to do, or the right equipment will necessarily be available. These lifts, or the use of temporary supports may be ‘one offs’ and will inevitably require more knowledge and skill than routine production tasks.

You should make sure:

• everyone involved in maintenance understands the risks
• an assessment of the risks (including the risk of disturbing something inadvertently) is completed and a plan of action decided on, before a heavy item is moved or temporarily supported
• there is someone competent to provide advice on safe slinging and on safe working practices for work involving heavy loads
• any equipment used to lift or support a heavy load is suitable and (where necessary) has been inspected and tested by a competent person
• heavy items are not left unsecured where they may tip over, fall or slip, and no-one works under suspended loads
• equipment is thoroughly cleaned with any loose material removed before maintenance activities commence.

Stored energy and energy sources

Isolation and lockout arrangements are essential to enable maintenance work to be conducted safely.

Before any maintenance work is undertaken you should:

• isolate the power or energy source (usually, but not exclusively, electrical energy)
• apply an isolation device and a sign to indicate that maintenance work is in progress
• dissipate any stored energy (such as hydraulic or pneumatic power)
• test and verify isolation is correctly applied.

For more information on isolation and lockout systems, see Section 15.17.

Confined space entry

A ‘confined space’ is:

• an enclosed or partially enclosed space and
• not intended or designed primarily for human occupancy
• may present a risk from one or more of the following at any time:
  • unsafe concentration of harmful airborne contaminants
  • unsafe concentration of flammable substances
  • unsafe levels of oxygen
  • substances that can cause engulfment.

These confined spaces can include tanks, load out bins, reclaim tunnels, crushers and poorly ventilated rooms.

People have died when entering confined spaces to carry out work. In some cases, multiple fatalities occur when would-be rescuers enter the space and become victims themselves.

You should minimise the time that tasks are undertaken in the confined space. This may be achieved by partially dismantling machinery or undertaking work outside the confined space before entry.

Where confined space entry is required, WorkSafe accepts the standard AS/NZS 2865 Safe working in a confined space as the current state of knowledge on confined space entry work.

For more detailed information see our quick guide Confined spaces: planning entry  and working safely in a confined space

Welding and gas cutting

Welding can have acute, chronic and long-term hazards to health and safety. These can act quickly or may show up only in the long term.

Oxygen under pressure and oil or grease can react violently, causing fire and explosions. Do not allow oxygen under pressure to come into contact with oil or grease.

Welding hazards include:

• Fires and explosions: These are an ever-present hazard with many welding processes.
• Burns: Welding causes items to become hot, creating a risk of burns and fires from hot metal and welding spatter.
• Fumes: Fumes generated by different welding processes may range from being of nuisance to being highly toxic. Health effects can occur very soon after exposure (for example, exposure to cadmium fumes can be fatal within hours) or may not show up for many years. Fume control requires appropriate ventilation equipment and may require advice from a specialist.
• Electric shock: Welding processes that use electricity pose both obvious and subtle hazards of electric shock – which can be Take precautions, as explained in our guide Health and Safety in Welding when using welding equipment. Expert assistance can be needed in some circumstances to identify subtle hazards. Appropriate equipment selection, set-up and maintenance is important and may require specialist advice to ensure safety.
• Compressed gases: Compressed gases in cylinders pose a number of hazards.
• Hazardous substances: Hazardous substances used during some welding processes can require highly specialised methods of control (such as extremely toxic hydrofluoric acid). Use a specialist in these situations.
• Toxic gases: Precautions for preventing toxic gases from causing harm are outlined in our guide Health and Safety in Toxic gases may be:
  • used in or generated by the process (for example, acetylene, ozone, nitrogen oxides and carbon monoxide)
  • generated when coatings on metal surfaces are heated (for example, galvanised steel, epoxy resins, degreasing agents or paint)
  • generated when the arc flash and some degreasing chemicals or paints react (such as phosgene or phosphine).
• Suffocation: Inert gases used during welding can flood an area and lower its oxygen content, especially in confined Suffocation can result. For more detailed information on confined space entry, see Section 15.16.
• Radiation: Arc flash is a well-known hazard of Standard precautions (such as PPE) should be used to prevent eye and skin exposure, both for the worker and others in the vicinity. Reflecting surfaces make exposure to radiation more likely. For more information on PPE requirements see our guide Health and Safety in Welding.
• Heat stress: Working for long periods in hot environments can lead to distress and, in extreme cases, to fatal heat Specialist advice must be sought if welders work in hot environments.
• Dust: Associated processes (grinding) may generate hazardous levels of dust.
• Noise and vibration: Noise and vibration levels during some welding processes can be high and should be controlled or appropriate hearing protection should be worn.
• Manual handling: Some welding processes may involve heavy or repetitive handling.
• Specific processes, including:
  • plasma cutting
  • brazing and soldering
  • thermal lancing.

For more information on hazards relating to worker health, see Section 4.

Providing health and safety information and advice on welding and cutting processes can be complex. There are many subtleties and traps for the unwary or inexperienced. Specialist advice may be required.

For more information on managing welding hazards, see our good practice guidelines for Health and Safety in Welding

In addition, the WorkSafe website has toolbox items to help raise awareness of the health risks from welding.

Clearing blocked crushers or hoppers

Clearing blocked crushers or hoppers can be very hazardous and plant operators have been killed carrying out this task. Blockage incidents can be greatly reduced by supplying material that is sized to match the primary opening.

Prevention of oversize feed material starts at the face, with good fragmentation. Removing oversize material before delivery to the plant and vigilant control of the crusher feeder, will make blockages less likely.

Causes of crusher blockages can be grouped under two main headings:

Stalling, due to:

• electrical or mechanical failure
• material jammed in the chamber causing an overload
• overfeeding material
• entry of tramp metal or wood
• accumulation of material in the crash box
• accumulation of fine material in the crusher discharge chute.

Bridging, due to:

• oversize feed material
• excessive clay or other fines in the crushing cavity, preventing small material passing through the crusher
• a foreign body in the crusher feed or discharge chamber, obstructing the feed material. 

Prevention of blockages in crushers or hoppers

You should make every effort to prevent oversize material or tramp metal entering the crusher feed hopper by:

• designing any site blast to achieve optimum rock fragmentation
• training and instructing the loader driver not to load oversize material
• using sizing bars or grids on crusher feeds
• following the manufacturer’s recommendations on the rate, presentation of feed and crusher settings
• instituting a programme of good housekeeping to prevent scrap steel entering shovel buckets
• ensuring the bucket size is appropriate to the capacity of the crusher
• regular inspection of metal parts (such as bucket teeth, dumper wear plates and drilling components) to make sure they are unlikely to break off and enter the crusher feed
• the strategic placing of electrical magnets or the installation of metal detectors to prevent tramp metal from entering the crusher
• the use of level indicators for feed control
• maintenance of drive systems
• removal and adequate cleaning of the discharge cbute.

A properly designed crushing operation should not need any person to be present on the crusher access platform during normal crushing operations.

Clearing blockages in crushers or hoppers

BRIDGED CRUSHERS

The preferred method of clearing a bridged crusher is by using a hydraulic arm. The hydraulic arm may be permanently mounted, or an excavator fitted with a static pick or a hydraulic hammer. Where the arm is operated remotely (for example, by radio control) CCTV is an invaluable tool in assisting the operator.

When hydraulic arms are not available, and it is necessary for a worker to enter the crusher to position hooks or slings, the crusher and feeder must be stopped, isolated and locked out in accordance with the manufacturer’s or supplier’s instructions and safe working practices.

Other options (which require more specialist expertise and competence) include gas or chemical expansion and hydraulic ramp plates. Consider other options subject to a detailed and thorough risk assessment.

The crusher should be shut off and isolated before considering the use of bars and hand hammers. Bars should never be used on or near a crusher while it is running.

Consider the risk of large pieces of feed material moving and causing trap or crush injuries.

Do not use wedges due to the risk of them becoming a projectile (this has caused fatalities in the past). 

STALLED CRUSHERS

A stalled crusher should be treated as possibly being jammed with tramp metal or wood, which could be ejected with fatal consequences. Safe systems of work should be issued to plant operators detailing what to do in the event of a crusher stalling which should include:

• clearing the area of all workers
• notifying the site manager of the stalled crusher
• isolating power to the crusher and associated plant
• undertaking a risk assessment for clearing the blockage
• implementing hazard control measures.

CLEARING BLOCKED CONE CRUSHERS

Many cone crushers are fitted (or can be retrofitted) with tramp metal hydraulic release systems or hydraulic assisted upper concave removal, to prevent or eliminate hazards associated with blocked cone crushers.

For cone crushers that do not have these systems, follow the guidelines above.

HAZARD OF ENTRAPMENT AT HOPPERS

There is the potential for an accident if anyone attempts to walk on the material that has been dumped into a hopper. The hazards are that they may be drawn into the feeding material, or, if the material is hung up, they may be drawn in when the material breaks free. The material in the hopper may look solid, but there may be a hidden void where it has bridged over the feeder. Anyone walking on the material is at risk of being engulfed if the bridged-over material collapses.

Mechanical devices should be provided (such as vibrators or air cannons) during normal operations so people are not required to enter or work where they are exposed to entrapment by the caving or sliding of materials.

Where people are required to enter or work near the hopper:

• provide platforms or staging
• stop supply and discharge of material
• lock and tag out equipment
• implement working at height procedures as required.

15.17 Lockout and tagout processes

Energy isolation is much more than putting a lock and tag on a switch.

To effectively isolate workers from energy, you need to know what the energy is, and how it can be safely isolated on specific machinery and vehicles.

Lockout and tagout (LOTO) systems are the placement of a lock and tag on an energy-isolating device. They indicate that the energy-isolated device is not to be operated until removal of the lock and tag in accordance with an established procedure.

Lockout is the isolation of energy from the system (a machine, equipment or process) which physically locks the system in a safe mode. The locking device (or lockout device) can be any device that has the ability to secure the energy- isolating device in a safe position (such as lock and hasp).

Tagout is the labelling process that is used when lockout is required. The process of tagging-out a system involves attaching or using an indicator (usually a standardised label) that indicates:

• why the lockout and tagout is required (for example, during repair or maintenance)
• the date and time the lock and tag were attached
• the name of the authorised person who attached the lock and tag to the system.

Only the authorised person who put the lock and tag onto the system is allowed to remove them. This procedure helps to ensure the system cannot be started up without the authorised person’s knowledge.

Safety devices such as guards or guarding devices are installed on systems to maintain worker safety while these systems are being operated. When performing non-routine activities these safety devices may be removed but there must be alternative methods in place to protect workers from the increased risk of injury of exposure to the accidental release of energy. Non-routine activities include maintenance, repair, set-up, or the removal of jams or misaligned feeds.

The main method used and recommended to protect workers from risk of harm in these cases is the use of a lockout and tagout procedure.

A lockout and tagout procedure will prevent:

• contact with a hazard while performing tasks that require removal, by-pass, or deactivation of safeguarding devices
• unintended release of hazardous energy (stored energy)
• unintended start-up or motion of machinery, equipment or processes.

LOCKOUT PROCEDURES AND WORK INSTRUCTIONS

The written lockout procedure should identify:

• what needs to be done
• when it needs to be done
• the tools available to do it
• who is supposed to do it
• who needs to be notified. 

Work instructions should identify how the lockout process is to be carried out in a step- by-step process including how stored energy is controlled and de-energised, how isolation can be verified, and how and where lockout devices are installed. Work instructions should be machine, equipment or process specific and include pictures or images of what is being described.

There should be one lockout procedure, and as many sets of work instructions as required, depending on the number of systems that require lockout.

For more information on how to use lockouts to safely isolate and de-energise the parts of machinery that could cause harm to workers when servicing this machinery, see our quick guide Keeping workers safe when servicing machinery

15.18 Permit to work systems

A Permit to Work (PTW) system is a formal documented process used to manage work identified as significantly hazardous by making sure all safety measures are in place before work starts.

A PTW system is also a way to communicate between site management, plant supervisors, operators and those who carry out the hazardous work.

Essential features of a PTW system are:

• clear identification of who may authorise particular jobs (and any limits to their authority) and who is responsible for specifying the necessary precautions
• training and instruction in the issue, use and closure of permits
• monitoring and auditing to make sure the system works as intended
• clear identification of the types of work considered hazardous
• clear and standardised identification of tasks, risk assessments, permitted task duration and supplemental or simultaneous activity and control measures.

The terms ‘permit to work’, ‘permit’ or ‘work permit’ refer to the paper or electronic certificate or form used to authorise certain people to carry out specific work at a specific site at a certain time. It also sets out the main precautions needed to complete the job safely.

When are permit to work systems required?

Consider permit to work systems whenever the intention is to carry out particularly hazardous work. PTW systems should not be applied to all activities, as experience has shown their overall effectiveness may be weakened. Permits to work are not normally required for controlling general visitors to site or routine maintenance tasks in non-hazardous areas.

Permit to work systems are normally considered most appropriate to:

• non-production work (for example, intrusive maintenance, repair, inspection, testing, alteration, construction, dismantling, adaption, modification or cleaning)
• non-routine operations
• jobs where two or more individuals or groups need to coordinate activities to complete the job safely
• jobs where there is a transfer or work and responsibilities from one group to another (such as shift changeovers).

Specially, you could consider permits for:

• work of any type where heat is used or generated (such as by welding, flame cutting, grinding) and work which may generate sparks or other sources of ignition
• work which may involve breaking containment of a flammable, toxic or other dangerous substance or pressure system, and work involving the use of hazardous or dangerous substances, including explosives
• work on high voltage electrical equipment or other electrical equipment which may give rise to danger
• entry and work within confined spaces
• pressure testing
• work affecting evacuation, escape or rescue systems
• work at height
• any other potentially high-risk operation.