Proper Sizing & Selection of Frames & Beams

Determining Frame Depth
The depth of the frame is determined by the size of the pallet. The most common pallet used is a 40″ wide x 48″ deep GMA wooden pallet. Using that as a guideline, the pallet should overhang the beams 3″ in the front and 3″ in the back thus making the frame depth 42″. The reason for this RMI rates beam capacities with 3″ front and back. When the operator is putting pallets away in the upper levels, it is wise to allow overhang so that the driver doesn’t inadvertently miss the beam when setting the pallet down.

Determining Height of Frame
These are quite a few factors in determining the height of the frame.

    1. Type of the sprinkler system in the building.
    2. Height of the building.
    3. Pitches roof or flat.
    4. Height to the underside of the sprinkler heads. The sprinkler system has a lot to do with the fire code. The distance underneath the heads can vary anywhere from 18″ to 36″.
    5. The lift height of the forklift to be used. Take the lift height minus 9″ to 10″. Five inches for the pallet height and 3″ to 5″ below maximum lift height. It is not good to run a lift truck up to maximum height all the time. It wears out the mast.
    6. Most importantly, the height of the load including the pallet.
    7. Six inches should be added to all of the above for pallet lift off.

Samples of Frames Offered:

    IU1842144 (Generally 14 GA, can be 12 GA).
    I – “I” Series
    U – Upright
    18 – Capacity 18,000 lbs. 3″ x 1-5/8″ columns
    42 – 42″ deep
    144 – 144″ high

    IU2442192 (Generally 14 GA)
    I – “I” Series
    U – Upright
    24,000 lbs. cap. (3″ x 3″ columns)
    42 – 42″ deep
    192 – 192″ high

    IU3042192 ( Generally 12 GA.)
    I -“I” Series
    U – Upright
    30,000 lbs. cap. (3″ x 3″ columns)
    42 – 42″ deep
    192 – 192″ high

* All of the above with 5″ x 7″ x 3/8″ footplates depending of seismic zone and load footplates can be larger.

The rolled formed uprights can also have 3″ x 1-5/8″ or 3″ x 3″ backer columns. The height of these backers may be anywhere from 2′ to full height of the frame.

Capacities of rack uprights drop dramatically in different seismic zones. Uprights that carry a 30,000 lb. capacity in a static (non-moving) situation may hold only 15,000 lbs. or less depending on seismic zone and beam spacing. Preliminary seismic calculations from a certified licensed engineer should be obtained to determine the actual capacity of the frame.

Sizing and Selection of Beams
Beams are sized on the basis of the loads to be placed on them. The first thing to consider is the width of the load to be stored. Next, find out how many loads are to be stored in a bay of racking. Normally this consists of two loads per pair of load beams. In the case of 144″ beams or tunnel beams, you might have three loads. Loading of the storage rack is limited by how much the client’s concrete floor can support.

The length of the beam is determined by adding the widths of the loads plus 3″ to 4″ in between plus 3″ to 4″ between the outside of the load and the upright frames. For example, if the the customer’s loads are 40″ to 42″ wide then a 96″ long load beam would be used. This is based on the customer using a standard THIS forklift. If a turret truck or a drexel truck is used, then the length of the beams would change.