Selective Pallet Rack Components

Pallet racking, or warehouse shelving is referred to by manufacturers as selective pallet racking and is by far the most common style most warehouses initially consider.  A basic configuration incorporates frames or uprights, beams or shelf supports, and the use of wire mesh or safety bars to form the shelf between the beams. Frames support the load placed on the wire mesh or safety bars which are supported by the beams. The components work together to efficiently store your inventory of materials. But this is only true if these components are configured and installed correctly.

It is not enough to simply say I want beams, frames, wire mesh and please install it.  The specifications of your load, the quantity of pallets or items,the specifications of the warehouse and the equipment you are using to pick and pack your racking system are all important. To simplify this article let’s assume we have a forklift able to reach the top shelf height of your racking and also let’s assume that your building can be outfitted with the approval of your landlord and local construction codes. (There are other articles in our Topic Blog on these topics).

Questions needing Answers


What material is being stored? Type of commodity – liquid, solid, fragile, hazardous?

Is it stored in individual boxes or on pallets? What are the overall width, depth, and height dimensions?” Is the load going to be uniform in dimension?

What will the weight of each box or pallet be?

What is your overall desired storage requirement total box or pallet positions. This will lead to calculating the number of rows, the number of bays in each row and and the number of shelf levels per bay.

How much space is available for the pallet rack system?

What is your ceiling height?

Will the racking be up against a wall or near other obstructions, such as sprinkler systems, heating units, fans, etc?

Do you require a NFPA letter to confirm that the fire sprinkler system in your space is sufficiently configured?

Will the storage system be located outside, in a cooler or damp, or corrosive environment?

Do you know the thickness and technical information for your floor slab?

What are the local permitting regulations that may affect your planned racking layout?

What accessories are required to complete the system installation with consideration given to safety, asset protection and building codes related to proper installation?  i.e. wire decks, row spacers, column guards, safety bars, shims, anchors, signage, etc.

Based on answers you collect to these questions we can begin to design your racking layout. Let’s look as some of the rack components in greater detail.

Pallet Racking Dimensions


Depth.

It is important that your load be supported by both the front and back beams of your shelf. Wire mesh or safety bars are not specifically designed to be load bearing but dependent on the beams for support. Frame depth is typically 4-6” less than the depth of the pallet to allow an overhang on the front and rear of the system. This overhang also assists the forklift driver when placing loads on the shelf. Common manufacturer depth dimensions include 24″ 36″ 42″ 44″ and 48″, with custom depths available for such non-standard applications such as carpet or furniture storage or oversized pallets.

Note: When configuring back-to-back rows of pallet racking you must provide sufficient space between the frames to account for the overhang plus some flue space.

Height.

There are a number of considerations when discussing height.

Worst or most likely overall height of the pallet or box load.

Space between the top of the pallet and the bottom of the next level – sometimes referred to as lift-off height which is typically calculated as 4-6″.

The height dimension of the shelf beam and any shelf accessories such as forklift space bars.

The number of shelves desired or needed to accommodate your overall pallet storage requirement.

Consideration must also be given to the distance to the ceiling or overhead obstructions.

Example case:

3 beam levels (capable of storing 4 pallet positions with one on the floor)
40″ tall pallets
4″ beam height

Example math: 40” pallet height + 4” beam profile + 4” liftoff = 48” first level. Add  48” second level + 48” third level = minimum 144” tall frame

Note: the top pallet load will sit above 144″. This means that the top of the load is at 184″ and you will need to also consider what clearance is required above the top of the load to meet local building code.

Width.

Shelf width is determined by the length of the pallet rack beam. In order to provide safe, easy load and unload of pallets on the shelf, we add space between the individual pallets on the shelf and between the pallet and the rack frame. This space is also referred to as flue space and is part of fire safety design. It is common to add 4-6″ for each of these spaces.

Example case:

2 pallets per beam level
40” wide pallet

Example math: 5” space + 40” pallet + 6” space + 40” pallet + 5” space = 96” wide beam

Note: When designing your overall row length don’t forget to account for the width of each frame.

Pallet Rack Load Capacity


It is very important to make sure your rack system is design to support the weight you plan to store. A quick search of youtube will be explanation enough!  The combination the various component specifications is needed to ensure the whole system is safe and will meet your needs. All components (frames, beams, mesh, support bars) must have loads within their engineered specifications.

Note. Any engineering review needed to meet local code and permitting will require load information.

Frame Load.

Frame load capacity is calculated on a per bay basis, or frame-pair. 

= Maximum load per beam level   x   Number of beam levels per bay factoring in the maximum vertical beam spacing (the distance from the top of one beam to the top of the next beam).

Manufacturers all maintain load ratings for frames based on the engineered specifications of the rack design. These specifications consider such things as quality of steel, thickness of steel, the column design, the cross-bracing design and the proposed beam spacing for your installation.

CMI is well versed in these specifications across many of our manufacturing partners and will guide your choice as part of our conversations with you.

Sample frame capacity chart.

Example case:

3 beam levels
2 pallets per level, each holding 2,500lbs.

48” maximum vertical beam spacing

Example math: 2500lbs. x 2 = 5000lbs. per level x 3 levels = 15000lbs. requirement per bay

Beam Load.

Beam designs are typically of two profiles – box or step/ledge. Step beams are more universal in their application and many manufacturers are migrating to produce only this style to simplify their production. Loads are calculated on uniformly distributed loads. If you have inventory that would place point loads on the shelf level this would need to be addressed as part of your beam selection.

Beam load is calculated as:

weight-per-pallet x number of pallets per beam level considering the overall length of beam.

Once again, each manufacturer will have slightly different load ratings for their beams and CMI is available to assist in making the right match.

Sample beam capacity chart.

Example case:

2 pallets per level with 2500lbs. per pallet
96” wide beam

Example math: 2500lbs. x 2 = 5000lbs. beam pair. 

Note: In your calculations of frame and beam capacity make sure the total capacity of all shelf levels does not exceed the frame capacity.

CMI is available to help with your layout and rack design, local permitting and professional installation. Call or inquire any time.