Pallet Racking Selection Guide.pdf

Pallet Racking Information and Guidance

Pallet racking is a very versatile and economical way to increase a warehouse’s storage capacity.

It is readily available from many commercial sources and can be effectively used in warehouses with ceiling heights ranging from 3650mm to 9000mm (12 to 30 feet) or more in height. There are two basic types of racking: pallet racking, and cantilevered racking.

PALLET RACKING CANTILEVERED RACKING

(NOTE: The yellow cantilever arm on the above photo is an “angled arm” which cannot be used with pallets.

Cantilevered arms must be level like the orange arms shown.)

Cantilevered racking specifications are well documented in OBO’s warehouse equipment specifications so they are not discussed here. The principles of layout, aisle width spacing and the like, are the same whether post ultimately uses pallet, cantilevered or some of both.

Frequently, commercial vendors will design warehouse racking layout as part of their proposal.

But whether done by a vendor, post or anyone else the warehouse layout, racking aisle width and material handling equipment (MHE) must ultimately be matched so that they work together.

Of greatest importance are the 90 degree “turn to stack” dimension of the material handling equipment and the racking aisle width: two critical design factors. Ideally, racking and MHE will be purchased as one package with a clause in the final contract insuring racking and MHE compatibility when installed.

Aisle widths of 2900mm to 3200mm (9.5 to 10.5 feet) are generally required for 2,500 to 4,000 pound (1100 – 1800Kg) three-wheel standup forklift or reach trucks. 3200mm to 3650mm (10.5 to 12 feet) wide aisles are needed for sit-down units with the same lift capacity.

Pallet Racking Specifics:

Heavy duty, high weight capacity, vertical upright supports are highly recommended. These should have a rated capacity of 28,000 lbs (12700Kg) for 7300mm (24 feet) high uprights, with horizontal pallet support beams at 1200mm (48 inch) intervals from the floor upward. The number and spacing of the horizontal pallet support beams is a critical factor in determining the actual weight capacity of any given upright support. The fewer the number of horizontal support beams or the greater the separation between the beams that connect two vertical uprights, the lower the overall weight capacity of the racking. Manufacturers have charts available to insure that the proper upright is used. In the sample below, note the capacity difference in column one between horizontal beams placed 48” apart and those placed 96” apart. The rack capacity has diminished by almost 2/3s: 16730 # vs 5710 #

Other factors:

Warehouse floors must be able to support the anticipated consolidated load. Remember that the entire load of a section of racking and its contents is concentrated on the four posts of the two vertical uprights: a total of perhaps 60 sq centimeters (9 square inches) per post.

A minimum of two pairs of horizontal support beams are required per section of racking.

The space between horizontal beams will be determined by height of the items to be stored in the racking. Beam spacing normally ranges from 1200mm to1800mm (48 to 72 inches) and can vary by level.

Racking design and capacity should be verified and certified by a professional engineer and include seismic evaluation. In seismic zones there are special designs and attaching requirements as well as some new developments in shock absorbing mounts. (see note below)

Height of vertical uprights should maximize space utilization and comply with overhead safety clearance requirements.

• When the building is equipped with a sprinkler system, the stack clearance below the sprinkler deflectors should be as follows:

o At least 45 cm (18 in) when stack heights do not exceed 4.5 m (15 ft) o At least 90 cm (3 ft/36 in) when stack heights exceed 4.5 m (15 ft);

• 90 cm (3 ft/36 in) overhead clearance is required in buildings without sprinkler systems, regardless of stack height.

• Additionally, in all facilities, a 45 cm (18 in) clearance around light or heating fixtures should be maintained.

Standard rack depth is 42 inches (1070mm) placed 15cm (6 inches) from the wall or 30cm (12 inches) apart (a flue) if positioned back–to-back. Tie-rods connecting the racks to the wall and to each other when back-to-back, are required.

• 900mm (36 inch) deep uprights are available and may be a better fit in some cases. If utilized, a 60cm (24 inch) flue in lieu of the 12 inch mentioned above should be left between back-to-back units to accommodate 48 inch deep, two way warehouse pallets.

All racking must be bolted to the floor front and rear.

In seismic zones there are special requirements and unique base isolation systems that are available. Consult a structural engineer for any installation in seismic zones.

Seismic Rack Base Isolation System

Pallet rack end posts must be protected by anti-ram guards.

Pallet racks should be tear drop style and equipped with locking devices to keep cross beams in place.

Tear drop upright Cross beam with locking device

Cross beams should be rated at 3,000 to 4,500 pounds (1400-2000kg) per cross beam section.

• Loads that exceed beam or rack weight capacity must be stored at floor level.

• Cross beams should be either 2400 or 2750mm (8 or 9 feet) long to maximize utilization of the cubic area while allowing safe loading and unloading of racks.

While it is possible to place and support a pallet on the front and back horizontal beam, a better and safer method is to use pallet rack decking to cover the area between the beams. Deck strength needs to match both the anticipated load weight and the capacity of the support beams but it is not self supporting and has a low PSI (pounds per square inch). See further explanation below.

• Wire or waterfall decking is required in warehouses equipped with overhead sprinklers.

o The number and type of support channels built into the decking are key factors when it comes to decking strength.

o “U” or inverted “U” channels are stronger that decking with flared end channels.

Stronger Weaker o The wire mesh or perforated metal decking itself, should hook over the front and rear of the horizontal support beams to keep it in place and prevent it from being dislodged during material handling operations.

o Remember the actual PSI (pounds per square inch) rating for the wire mesh is very low – people should not walk on it and heavy items should be palletized to distribute the item’s weight evenly across the decking and rack.

• Waterfall decking for cantilevered racks are constructed differently as they must be self supporting. The material used is the same as used for mezzanines and industrial walkways: welded steel slats or interlocking pressed steel slats.

• Solid metal decking can be used in facilities without fire suppression systems. Plywood and other combustible material should not be used as decking for safety and fire reasons.

Warehouse pallets are another key part of the racking system and need to have support runners that rest on and distribute load weight between the front and back horizontal cross beams.

• Plastic/Resin 40” X 48” (1000 X 1200mm), four way pallets are recommended for most items.

• A small quantity of other size pallets, 30 x 42 (760 X 1065mm), 72 x 48 (1800 X 1200mm), etc. maybe very useful to have - especially for items stored at floor level.

• All items that cannot be physically handled, stored and retrieved, by the warehouse team while standing on the warehouse floor, should be palletized and handled by MHE for safety and operational efficiency reasons.

Safety netting should be attached to the back side of any racking that is located adjacent to pedestrian walkways.

• Netting is an inexpensive way to protect employees and minimize product damage.

Rack maintenance and repair is an often forgotten consideration. Accidents happen and when a forklift hits a rack upright, disaster and serious injury can occur.

• Damaged racks can be repaired, but just trying to weld a piece of steel over the damage and hope for the best is a dangerous practice.

• A number of companies provide a wide range of well engineered repair parts that will leave the racks stronger than the original replacement – without having to unload and tear apart a large section of racking.

Rack upright repair pieces

The A/LM/OPS Warehouse Team (Tom Widenhouse and Mike Carney) request that you allow them to review all racking and forklift proposals before Post finalizes any purchases. They would also be happy to answer or assist with any warehouse or supply chain questions your post might have.