The variables to consider when designing a pallet rack system are:
The basic components of pallet rack systems are uprights and beams. Uprights are the vertical component consisting of two columns connected by vertical and diagonal bracing. The depth of the upright used depends on the width of the pallets being stored. The most common pallet depth is 48” and the most common upright is 42” deep. This allows for the pallet to be placed on the beams with an approximate 3” overhang front and back. If you do not have this overhang it is too difficult to place pallet without missing the front or rear beam and having the pallet fall in between the front and rear beam. The weight capacity of the upright is dependent on the capacity and number of beams .Uprights are normally anchored to the concrete slab using concrete wedge anchors.
Beams are the horizontal component of pallet rack systems which are connected to the uprights at either end (left and right) and support the pallets being stored. There are two beams (front and rear) per set of two uprights. The length of beams are determined by the widths of the pallets being stored. Generally two pallets are stored side by side on a pair (front and rear) of beams. Since the most common pallet widths are 40” and 48”, the two most common beam lengths are 96” and 108”. This allows for the pallets to be stored side by side and leaves room between pallets and between pallet and upright. The capacity of the beams being used are dependent on the weight of the pallets being stored.
Two uprights with beam levels in between are referred to a bay of rack. Two or more bays of rack are referred to as a row of rack. Note that two or more bays share common uprights. Two bays of rack in a row contain three uprights. Ten bays of rack in a row contain Eleven uprights.