Storage systems

A variety of systems are used for storing goods, from pallets to static racking. The method of storage depends on the shape and fragility of the article. Long thin articles are generally stored in some form of horizontal racking and box-shaped articles or loose materials in sacks built into a stack, with suitable bonding to ensure stability.

 

Cylindrical articles can be stored on their sides or on end. When such articles are stored on their sides, the floor-level tier should be properly secured to prevent movement. Subsequent tiers can rest on the preceding one or be laid on battens and wedged (see Safety in the storage of steel and other metal stock HSG246).47

 

Storage areas should be specifically designated and clearly marked. The layout of the storage and handling areas should be carefully considered to avoid tight corners, awkwardly placed doors, pillars, uneven surfaces and changes of gradient. Consider the use of guard rails to protect pedestrian routes.

 

Where materials are handled by crane or lift truck, they should be placed on battens or other suitable material, so that a sling or the forks can be inserted. Pallets handled by crane should only be lifted by attachments suitable for that pallet design. A ‘C’-hook pallet attachment should be used where appropriate. Where fork-lift trucks are used, it is possible for most materials to be palletised and stacked as complete pallet loads, or stored on pallet racking.

 

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. It is recommended that pallet design should satisfy the requirements of BS EN 13698. Worldwide, the design and dimensions of pallets vary.

 

If pallet racking is used in the warehouse, the type is of key importance when considering which type of pallet to use. Consider the bending stresses exerted on timber, flat and other pallets from this type of storage.

 

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:

poor design

poor construction

the use of a pallet which is unsuitable for a particular load

the continued use of a damaged pallet

bad handling; or

the use of a pallet which is unsuitable for a particular racking system

 

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, eg palletised loads approximately to the internal height of closed vehicles. This should only be done where you have carefully assessed the stability of the load components, the load configuration and any special features such as wrapping, strapping etc.

 

Safe pallet use

 

Consider the following for safe use of pallets:

You should have an effective system for pallet inspection. Damaged pallets should be removed from use.

All pallets should be inspected each time before use, to ensure that they are in a safe condition. Withdraw

damaged pallets for suitable repair or destruction.

Empty pallets should be carefully handled and not dragged or thrown about. They should not be handled by methods likely to loosen deck boards. Wedging the platform of a sack barrow between top and bottom deck boards can cause damage.

Hand-pallet truck forks of unsuitable length can cause baseboard damage and be dangerous to workers.

If hand-pallet trucks are used, take care to ensure that the small finger wheels (also known as trail or guide wheels) do not damage the base boards. Chamfered edges to the bottom deck boards will assist entry of the pallet truck fork arms.

Expendable pallets, ie pallets designed for one delivery only, should be clearly marked to this effect and are not normally suitable for storing on racking. They should not be reused.

Take care when using strapping to secure loads to pallets, as deck boards can be pulled from the bearers.

To avoid damage to pallets and to lift palletised loads safely, the forks of a handling device should extend into the pallet to at least 3/4 of the pallet depth.

The forks should not extend beyond the pallet, as protruding forks could:

make contact with or lift an adjacent load(s), causing it to overturn or ––collapse; or

find their way underneath a fixed structure (eg racking) during lifting, causing ––overloading of the truck and/or serious damage to the racking structure.

 

 

Instruct operators on the correct method of handling pallets, emphasising:

the mast should be in the vertical position when entering and leaving the pallet, forks should be level with the pallet boards;

the pallet should be positioned against the heel of the forks

the forks should enter the pallet squarely

the forks should be correctly spaced for the pallet load being lifted

pallets should not be pulled or pushed along the ground

loads should be carefully and gently placed on the stack below

pallets should be lowered onto racking beams, and never slid across or along the top surface of such beams.

 

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. The most common types found in warehouses are described in Table 9. Table 10 details terms commonly used for racking systems.

 

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.

 

Common types of racking systems used in warehouses

Racking system

Description

Adjustable pallet racking

A system of upright frames connected by horizontal beams to provide pallet storage levels,

which can be adjusted vertically. Each pallet storage position can be accessed individually.

Mobile racking

The racking is mounted on movable base frames running on rails; it can be power-operated, manually operated or mechanically assisted.

Cantilever racking

Racking incorporating cantilever arms, either fixed or adjustable.

Live storage racking

A live storage system provides a block of storage in depth, which has a rear or ‘loading face’ and a front or ‘picking face’. Goods are conveyed from the loading to the picking face either by gravity using an inclined surface or track or by horizontal powered conveyor such that two aisles are necessary to service a block of storage, whatever the depth. This method of storage ensures that the first-in-first-out system operates and is suitable for pallets, boxes, and containers etc, all of which have specific requirements within a live storage system.

Push-back system

A live storage system providing a block of storage in depth, where picking and loading are both done from the front face of the block. Goods are conveyed to and from the storage position either by gravity using an inclined surface or track or by horizontal powered conveyor such that only one aisle is necessary to service a block of storage. This method of storage ensures that a first-in-last-out system operates and is suitable for pallets only.

Drive-through/drive-in racking

This system provides blocks of static storage where pallets are stored two or more deep. By driving into the storage lane, access is gained to pallets supported along their sides on beam rails cantilevered from the frames.

Drive-in system: the lift truck drives into a lane and reverses out.

Drive-through: similar to drive in, but the truck may drive through the block from one aisle to another.

 

 

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