Pallet Racking

Pallet racking is essential to modern warehouses, retail centres and other facilities. It enables the efficient storing and moving of goods. Pallet racks link together to form pallet racking systems. These can be vast, depending on the space available and the nature of the application. In all pallet racking systems, space utilisation is vital to achieve the best results. This is known as maximum storage density.

A pallet rack has numerous structural components. Pallets rest on horizontal struts called beams. Beams mount onto upright frame columns (also called columns or uprights) using clips or bolts known as pallet supports. Diagonal and horizontal braces welded into the frame provide extra strength, stability and rigidity. This structure is the basis of pallet racking.

Decks

Wire decks in pallet racks act as support platforms that distribute the load more evenly. In a warehouse pallet racking system, wire decking allows the easy shelf content identification and holes in the mesh prevent the accumulation of dirt and debris. Wire mesh decking comes in a variety of types and dimensions.

Footplates support pallet racking at the column bases. Bolted to the concrete floor and made from thick steel, these serve as anchors and keep the racks stable. Metal plates called shims, installed beneath the uprights, level out racking resting on uneven floor.

Racking Uprights

Uprights arranged in back-to-back rows in a pallet racking system sometimes use row spacers. Mounted between adjacent columns, these keep the rows straight. Row spacers also strengthen the pallet racking and increase its stability. Wall ties further support uprights arranged in a row along a wall.

Damage to the bases of columns in a pallet racking system is dangerous. It can weaken the entire frame and cause it to collapse. Forklift collision is a common cause of these kinds of accidents. Protective shields known as column protectors, installed around the upright bases, minimise damage.

The sacrificial leg, developed by a major racking supplier, is an innovative alternative to column protectors. It replaces the first 1000mm of an upright and when damaged, can be removed and replaced in as little as twenty minutes, without disturbing the rest of the frame. It cuts the cost of replacing frames within a pallet racking system and means repair work may take place as soon as an accident occurs, minimising downtime.

Types of Pallet Racking

Different types of pallet racking are available to suit different applications. Perhaps the most common is wide aisle pallet racking, used for storing palletised loads. Wide spaces between the aisles allow excellent access but may only utilise up to 40% of the floor space. Wide aisle pallet racking requires no specialised handling equipment and supports each pallet. Each pallet is accessible, leading to fast throughput and efficient loading and unloading.

Narrow Aisle Racking

Narrow aisle pallet racking utilises space better. The aisles are typically 1.6 metres wide, freeing up to 45% of space taken up by a wide aisle arrangement. This increases the storage capacity. Narrow aisle racking supports each pallet, which means stock rotation and accessibility are as good as a wide aisle racking scheme. Specialised equipment, such as reach trucks, is often required to access goods in narrow aisle pallet racking.

Drive In Racking

Drive in pallet racking eliminates the aisles and uses lanes of racking to store blocks of goods. Forklift trucks drive into the lanes to pick and place pallets. This obtains a higher storage density at the expense of selectivity. The first pallet into a lane will be the last out. However, this is not a disadvantage if the warehouse receives and dispatches pallets in batches. Drive in pallet racking is capable of operating very quickly, especially when using lead-in rails to guide the forklifts into the lanes. Drive in racking supports each pallet to prevent damage from crushing.

Push Back Racking

Push back pallet racking uses special rack beams and fabricated subframes running from front to back in each bay, which have wheels that run in tracks. As the rear rack beam is slightly higher than the front, the subframe comes to rest at the face of the bay. When a forklift places the first pallet in a bay, it rests on the subframe. Putting a second pallet in pushes the first one back. What this means is when the front pallet is removed, the others roll slowly and safely forward.

Push back pallet racking enables areas of rack backing onto a wall to be fully utilised. It combines the benefits of drive-in racking with pallet live storage. Push back pallet racking means pallets can be accessed four deep from one face and is ideal for order picking operations.

Powered Mobile

Powered mobile pallet racking comprises conventional pallet racking fixed upon a steel framed base. Tracks set into the floor allow the base to move on electrically powered wheels. This system allows users to move a run of racking, creating an access aisle. Powered mobile pallet racking utilises up to 80% more floor space than a wide aisle system, while retaining access to every pallet.

By using special, high-speed cranes on rails to move pallets, users can build pallet racking systems taller and narrower to utilise space efficiently. The cranes, which can be computer controlled, move vertically and horizontally simultaneously, resulting in rapid loading and unloading. By using conveyors and automated guided vehicles (AGVs), users can automate the whole pallet racking system, reducing staff costs.

Racking Regulations

With so many racking types and companies that supply it, making the right choice is essential. As well as issues such as cost effectiveness and efficiency, there is health and safety. This is governed by the Storage Equipment Manufacturers’ Association (SEMA) and British Safety Standards (BSS).

In any pallet racking installation, there are two kinds of strength. The first is the strength of the raw materials used to make the rack. There are various recommendations from SEMA for material specifications. These include hot rolled and cold formed steel sections that conform to the appropriate British Safety Standards.

The second is that of the assembled rack installation. Flexing and bending is normal in most racks, but users must be aware of the restrictions. Pallet racking that will support timber pallets may not support heavier post pallets. This is because of the beam centres. In one set of circumstances, a pair of beams could have a one-ton capacity. Under another, the same pair may only have a ¾-ton capacity. Manufacturers usually state the safe loading limits for a pair of beams.

Frames consisting of pairs of uprights braced together also have load limits. Exceeding these will endanger the stability of the pallet racking installation. Manufacturers should state frame load limits, but there are three factors to take into account:

1. Beam spacing - the further apart they are, the lower the load capacity.
2. Beam size and number of beam levels to a bay.
3. Number of bays along the length of a rack.

The first two factors determine the overall stability of the rack. There are special design rules governing the frame loads for single bay and/or single beam level racks (e.g. raised storage areas). The manufacturer should be consulted before any beams are adjusted or removed, and before physical alterations are made to uprights or bracing.

The height-to-depth ratio is important when assessing the stability of a pallet racking system. The height of a rack, for the purposes of assessing height-to-depth ratio, is the height of the topmost loaded beam. The depth is the overall depth of the rack frame. Where racks are joined together back-to-back to form double-sided racks, the depth is the overall depth of the two frames plus the space between. This is dependant on the frames being joined together with run spacers, which are not more than 2.5 metres vertically apart.

Fixing racks to the floor is vital when using forklifts in a pallet racking system. Even the best drivers bump a beam occasionally and freestanding racks topple in these circumstances. How a rack is fixed depends on the height/depth ratio. If it does not exceed 6:1, only the perimeter uprights need fixing to the floor. If it over 6:1, but below 10:1, all the uprights need fixing to the floor.

If the height/depth ratio of a pallet racking system exceeds 10:1, each frame must be restrained by connections to other substantial structures, which are capable of providing the support necessary.

Maintaining pallet racking properly is essential to keeping it safe. Abuse typically occurs where there is a high turnaround and rapid movement of goods, particularly so in wide aisle pallet racking systems that use reach and counterbalance trucks. Unit loads and pallets in poor condition are hazardous. Clean floors, skilled forklift operators and well-maintained forklifts also help keep pallet racking safe.

Qualified personnel should carry out regular inspections of pallet racking installations. Worker should report accidents immediately, in order that repair work can take place swiftly. Common hazards that require attention are:

• Mis-alignment of racks.
• Incorrect location of beam connectors.
• Loose fixings.
• Dislodgement of accessories.
• Spillage of goods.
• Greasy, slippery floors.
• Forklift truck deficiencies.

Sometimes, damage may be irreparable and a section of the racking will need replacing. Things to look out for include:

• Damage that significantly changes the original cross-sectional profile of any main load bearing member.
• Damage that significantly deforms any main load bearing member.
• Damage that weakens jointed members through weld breakages or failure of bolts.
• Damaged pallets.

Choosing the right pallet racking installation is crucial. A good racking supplier will provide professional advice and assistance. Well-built pallet racking brings enormous benefits, including a safe, efficient running working environment. Trent Design supplies a range of pallet racking.