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Pallets

A pallet is a portable platform, with or without super-structure, for the assembly of a quantity of goods to form a unit load for handling and storage by mechanical means. They are widely used for the storage and transit of goods. A reversible pallet is a pallet with similar top and bottom decks, either of which would take the same load. They are not suitable for use with hand-pallet trucks, as the small wheels on the forks will cause damage and separation of the bottom deck.

A wing pallet is a flat pallet whose deck (or decks) project beyond the outer bearers to facilitate the use of lifting slings. They are not suitable for drive-in or drive-through racking where the dimension between racking beam rails has to match the overall width of the pallet, as the wings are not strong enough to support substantial loads.

Flat pallets, post pallets and box pallets are the most common types of pallets used in warehouses. A cage pallet is a special design of pallet that has a superstructure of four attached collapsible vertical sides, usually slotted or mesh. Such pallets are designed to permit stacking by mechanical means. They can be used both for transit of goods and as a display and selection unit for merchandising in retail outlets, ie goods can be put on sale without further unpacking and handling.

Pallets can be constructed from a number of materials, such as steel, plastic or timber. Flat pallets are usually constructed of timber. Pallets should be of sound construction, sound material and of adequate strength.

Using flat pallets

Flat timber pallets form an essential part of many mechanical handling systems in warehouses. Accidents directly attributable to these pallets usually arise from six main sources:

The majority of pallets are designed for carriage of a particular class or type of goods and to be handled or stored by a particular method, eg a pallet intended for the carriage of boxed cereals, handled by a lift truck and stored singly in racking, will not usually be suitable for goods such as cans of paint, lifting by bar sling or for stacking four high. A pallet designed specifically to carry evenly distributed loads, such as boxed cereals, may not be strong enough to carry concentrated loads, such as an electric motor of the same weight.

Where mixed racking systems are installed within a single warehouse, the use of pallets which require a different orientation for each racking system, eg a four-way entry pallet without base members ‘x’, are not be regarded as suitable. Use a pallet design that is suitable for all your racking systems, regardless of orientation.

Loading pallets

Pallets should be loaded to an established pattern designed to achieve maximum stability and safety within the rated load. Loads should be applied gradually, and unless the pallet has been specifically designed for point loading, should, as far as possible, be uniformly distributed over the deck area. As a general guide, the load height should not exceed the longest base dimension of the pallet. Shrink or stretch wrapping the load usually provides greater security, minimising the possibility of movement of goods – it may be possible, in certain circumstances, to safely transport loads taller than the largest base dimension of the pallet.

Stacking palletised loads (block stacking)

Avoid stacking palletised loads of cartons and packs that are capable of being crushed, as the strength and stability of the stack cannot be maintained. Loads that are capable of being stacked directly on top of each other should be positioned on a firm level base. It may be necessary to provide additional packing on top of the lower palletised load, depending on the characteristics of the load and design of the pallet.

Generally, such stacks should not be more than a 4:1 ratio between height of stack and the minimum depth/width of pallet. Four loads high might also be considered a maximum due to the potential problem of crushing the goods on the bottom pallet. In some circumstances, dependent on the height, strength and stability of the loads, taller stacks may be built. The maximum permissible height may be up to six loads high, provided that the pallet itself and the packaging of the stored goods are designed to exceed the four-high strength.

Maintain adequate clearance between rows to ensure safe stacking and withdrawal. Check stacks periodically for stability and take corrective action where necessary.

Safe pallet use

Consider the following for safe use of pallets:

Only authorized, trained and competent people should operate lift trucks Instruct operators on the correct method of handling pallets, emphasizing:

Turntable pallet stretch-wrap machines

These machines are commonly used in warehouse premises to wrap a pallet load in a sheet of plastic film to provide stability, weatherproofing and protection to the load during storage or distribution. The pallet load is usually placed onto the machine turntable using a lift truck or pallet truck; the plastic film is then attached to the pallet load manually, eg by tying to the pallet, and wrapping is carried out by rotating the load on the turntable while the film reel is carried vertically up and down on a column. Some machines are fitted with a top clamp, which descends to steady the pallet load while the wrapping cycle is carried out. Common hazards associated with the use of turntable pallet stretch-wrap machines include,

In some specialised warehousing situations, pallet wrappers or strappers that are conveyor-fed and operate automatically (including those where the pallet remains stationary while the reel passes round it on a rotating arm) may be found. Such machines generally require a higher standard of guarding, and as a minimum, should be provided within interlocked enclosures.

Pallet inverters

These mechanically operated machines are designed so that a defective pallet at the bottom of a palletised load can be easily removed and replaced with a sound pallet, without the need to de-stack the load by hand. They may also be used to change from one type of pallet to another. Pallet inverters should only be used where a pallet carries non-crushable materials stacked in a manner that allows inversion. The basic operation is as follows:

Hazards at pallet inverters are known to include,

After assessing the risks associated with the use of pallet inverters, the following precautions should be adopted:

Pallet converters

A pallet converter is a frame (usually metal) that fits onto a wooden pallet to enable crushable or unevenly shaped loads to be stacked. The pallet converter should be rigid even without a load or with a part load, and never rely on a full load to ensure rigidity. Locking pins or other devices used to locate and lock the converter onto the pallet should be in good working order and free from defects. To ensure the pallet converters are in a condition to be stacked safely, there should be an effective system of control over pallets and component parts of converters that ensure all the component parts are compatible with each other. Damaged or defective pallet converters should not be used.

Racking systems

The term ‘racking’ is used to describe a skeletal framework, of fixed or adjustable design, to support loads generally without the use of shelves. It is usually qualified (ie pallet racking, tyre racking, drum racking, etc). Racking systems are widely used in warehouses as there are considerable space advantages over floor storage and they provide for easy access and retrieval of goods. There are many different types of racking system.

All racking systems should be of good mechanical construction, of sound material, adequate strength and installed and maintained in accordance with the manufacturer’s instructions. The maximum safe working load and design configuration for any racking installation should be conspicuously displayed.

Some common types of racking systems in warehouse are,

Racking installation

The requirements for the safe installation of racking vary according to the type and size of the system, and the nature of the building or area for which it is intended. Safe working loads, heights, widths and equipment tolerances should be set by the designers and manufacturers of the total system. The basic principles for safe installation are as follows,

Pallet stops

Using pallet stops attached to racking structures may increase the risk of structural damage from the load or thrust that may be applied to the racking. If racking layouts are correctly designed to give adequate clearances between back-to-back pallets or loads, then pallet stops are unnecessary for a trained and competent driver to deposit a pallet correctly and safely.

Racking stability

The main factors that influence the stability of the racking installation are the height-to-depth ratio and whether it is fixed to the floor or other suitable parts of the building structure. Free-standing racks (ie not fixed to the floor) should not be used in areas where lift trucks, order pickers or other mechanical handling devices are used. Where racks are subject to imposed loads from the storage of product, plus horizontal loads from loading and unloading, the minimum requirements for floor fixings should be,

Racking protection

Where racking is likely to be struck by lift trucks and other vehicles, it should be protected. Generally, such damage is at the lower levels of the racking – use renewable column guards to minimise the risk of damage from accidental impact. Corner uprights in a run of racking are especially at risk and should be suitably provided with a protective device in a conspicuous colour. Retrofitting upright protection devices to an existing aisle where they have never been provided can have the effect of reducing the available clearances for fork-lift truck maneuvers, which can in some circumstances increase the amount of damage caused. Such situations need consideration on a case-by-case basis.

Placing or receiving stock from racking or shelving

Where it is necessary to place or retrieve stock from racking by hand, the following basic principles should be adopted,

Picking from in-rack walkways

Mezzanine floors can be provided between racking runs so that products can be picked or replenished at more than one level. This increases the picking locations in a given floor area where numerous operators can pick simultaneously. Typically, pallet racking is used where the replenishment side is fed by fork-lift truck and manual picking the other side. This can be single/double pallet depth or using live storage for greater capacity.

In addition to the general risks associated with working at height, care should be taken to ensure that workers are protected at picking locations:

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