Flatness and levelness of warehouse floors

Level and flatten warehouse flooring is crucial for the proper circulation of handling equipment, for example, in standard drive-in pallet rack facilities. Some of these require a concrete floor to be very level to prevent breakdowns in the machines and, even more importantly, problems in the installation itself.

The most serious problems are in systems with turret trucks (either trilateral or bilateral), due to their great lifting height and speed of operation. With these machines, the leveling of the flooring is an extremely critical factor, since they work with minute clearances in the aisles between the shelves. Any variation in the floor can lead to a tilting of the device which, no matter how small, poses a risk to the entire installation.

Checking the leveling of warehouse floors is intensive work

 

When a very narrow aisle forklift moves over an unleveled surface, it rocks. In the absence of a suspension system, this immediately transmits the motion to the mast. Given the considerable height of this device, a single millimeter of unevenness at the base can turn into, at great heights, several centimeters of movement, as shown in the illustration above. This may lead to accidents with the loads or shelves being hit, with the danger that this entails.

Deviation will also decisively influence the height positioning of the fork assembly, creating the risk of blows when they are extended to collect or deposit a load.

Because of the above, and to avoid any danger or unfortunate incidents in the future, the floor in a working environment with narrow aisle machines must be extremely level. It is not enough for the construction company to assure that the surface is properly leveled. Experience shows that it is essential to have the relevant certification, and even the table of the sampling performed after completing the flooring.

Checking the leveling of the floor is hard work, requiring great care and the use of very accurate optical instruments. The floor must comply with parameters that vary depending on the storage system used.

Checking warehouse floor are level is hard work

Image provided by Pavindus S.A.

Correct floor leveling is vital to avoid breakdowns in handling equipment. 

 

Leveling requirements differ depending on whether the installation is class 100, 200, 300, or 400. This class is determined by certain factors that are taken into account in the EN 15620 quality standard. In terms of handling equipment used, storage systems are classified as follows:

 

Class Aisle type   Suitable for:
100 Very narrow

Pallet racking unit less than 59 ft high, with very narrow aisles and operated by AS/RS stacker cranes for pallets.

200 Very narrow Pallet racking unit with very narrow aisles, operated by AS/RS stacker cranes and with an additional system for positioning unit loads.
300 Very narrow

Pallet racking unit with very narrow aisles, operated only by
forklifts that do not need to turn in the aisle to load or unload units. The forklifts are guided along the aisle by mechanical or induction guides.

300A  

The operator continually moves up and down with the unit load and has manual height positioning. When the driver is at ground level, he or she has a closed circuit viewing system or the equivalent.

300B  

The operator remains at ground level at all times and does not have indirect viewing devices.

400 Wide

Pallet racking unit with narrow aisles, wide enough to allow the forklifts to turn 90º for loading and unloading.

  Narrow

Pallet racking unit with aisles with less space, which can be used by more specialized forklifts.

 

Before analyzing floor leveling requirements, it is necessary to explain the difference between floor leveling and flattening, which is shown in the following illustration:

 

Graph displaying a level vs. flat warehouse floor surface

 

1: Profile of a leveled but not flat floor.
2: Profile of a flat but not leveled floor.
X: Distance between two fixed points on uneven ground (in this example, 9.8 ft).
E: Height difference between the two fixed points 9.8 ft apart.

 

The term “9.8-ft grid” when used in the following section refers to a set of points on the surface of the ground, 9.8 ft from each other in directions perpendicular to the building.

 

Requirements for a class 400 floor (for wide and narrow aisles) 

All points in a 9.8 ft grid must be within ±.58 in of the horizontal reference. The table below contains the maximum values of E (the height difference between two points), according to the truck used and the height of the top level of the racking unit installed.

 

Type of truck Height of top level Maximum value of E
Without sideshift More than 42.3 ft .088 in
Without sideshift  26.2 ft to 42.6 ft .128 in
Without sideshift Up to 26.2 ft .157 in
With side slider Up to 42.6 ft .157 in

 

Requirements for a class 300 floor (very narrow aisle)

Facilities with trucks for class 300 (very narrow aisle) must meet very strict leveling requirements. One must bear in mind that a small slope of millimeters in the floor can become centimeters of tilt for the mast of the truck, with the associated risk of accidents.

The requirements for proper leveling of the ground in 300 class facilities are specified in the EN 15620 standard. The following table is provided as a summary to show the maximum values of parameter Zslope, which indicates the cross-slope of the aisle between the centers of the front wheels of the truck and E, which represents the height difference between two adjacent points 9.8' apart. 

 

Height of top level Value of Zslope Maximum value of E
More than 42.6 ft .051 in .128 in
26.2 ft to 42.6 ft .079 in .128 in
Up to 26.2 ft .098 in .128 in

 

All points on the flooring must be within ±.59 inches of the horizontal reference.

 

Requirements for class 100 and 200 floors (very narrow aisle)  

For classes 100 and 200, despite being facilities with very narrow aisles, leveling requirements are not as strict as those for class 300 floors, given that the stacker crane does not move on the flooring, but rather on a lower guide rail.

In accordance with EN 15620, the flooring leveling requirements are as follows:

For classes 100 and 200, despite being facilities with very narrow aisles, levelling requirements are not as strict as those for class 300 floors, given that the stacker crane does not move on the flooring, but rather on a lower guide rail.

In accordance with EN 15620, the flooring leveling requirements are as follows:

Aisle length Leveling with respect to horizontal ref.
Up to 492 ft +/- .59 in
820 ft +/- .79 in

 

For intermediate aisle lengths (between 492 ft and 820 ft), the data can be interpolated linearly.

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