FEATURE HANDLING, STORAGE & RACKING
SAFETY IMPLICATIONS of uniformly distributed loading
Best practice involves more than stacking a shelf to its limit. Sam Cant of Rapid Racking explains the issues around uniformly distributed load (UDL) and its safety implications
I
ndustrial and warehouse shelving may look simple; a few shelves organised
into nice neat rows with enough room to access them. However, one of the most overlooked issues is uniformly distributed load (UDL) or uniformly distributed safe working load (UDSWL). UDL describes the way in which the load is spread across the shelf area. This is important because the weight of the items being stored can be heavy and an uneven weight distribution can negatively affect the stability of the racking and therefore the security of the items stored which has significant safety implications. In all storage areas personnel safety is the priority but product safety and storage must be considered, particularly when it is likely that insurance may not cover damage if the shelving system has been found to have contributed to the loss. As a result, warehouse or storage planning prior to the installation of shelving or any other storage solution must take into account the weight of what is being stored and how it is likely to be distributed once stored.
AVOIDING POINT LOADS A vehicle gearbox for example will weigh anything from 30-80kg. When several units are stored in a warehouse on a shelf ready for distribution into the supply chain the total weight could easily be 500+ kg. If that load is concentrated
in the middle of the shelf (a point load) there is the potential for shelf ‘deflection’ which means it can begin to sag in the middle and potentially fail. Point loads should therefore be avoided. As an example, a shelf may be rated as being able to carry a 125kg load but could be at risk of failure if a 100kg point load is placed in the centre of the rack. Similarly, a large number of small boxes
may get close to a uniformly distributed load without leading to failure because the weight is spread evenly across the shelf. However, a smaller number of larger items unevenly distributed has the
After the successful implementation of the first installation in Turkey at DeFacto in 2013 TGW was awarded expansion of the site in Cerkezkoy.
AUTOMATED STORAGE AND RETRIEVAL SOLUTION This will result in the largest direct carton
handling and automated apparel site in Turkey which will support DeFacto’s B2B and B2C business. TGW will integrate the warehouse management system from inbound to outbound. In addition to the 12 existing aisles 16 mini-load warehouse aisles with Magito storage and retrieval machines serving a further 340,000 storage locations will be installed. TGW will implement inbound operations including
volume measurement and rework and a second bomb-bay sorter including automated carton opening. Furthermore, there will be an empty carton reuse process and automated closing operations for outbound cartons including shipping label application. Direct loading and palletisation for outbound operation will be added. TGW will support DeFacto with ongoing quality control and ramp-up.
TGW 24 FEBRUARY 2016 | FACTORY EQUIPMENT
www.tgw-group.com
Adding levels can exceed the loading capacity of the upright posts or frames which can result in buckling and potential safety risk
potential to give ‘point loads’ along the shelf which could cause deflection in several different places. A warehouse operator standing on a bottom shelf of a racking system is in effect creating a point load often of a considerable value. Clear guidelines need to be given to personnel to avoid such practices. It is important to remember that it is not only the shelves themselves that have a maximum load capacity. Consideration should be given to the
number of shelf levels permitted within a bay. It is very easy to purchase from websites or catalogues shelving that can be bought in bays and easily extended with additional levels. However, this can exceed the loading capacity of the upright posts or frames which can in turn result in buckling and a potential safety risk. It is important to assess what effect the vertical pitching of shelf levels can have on the total bay capacity. I recommend that shelving and racking
users get advice; to install and use it safely requires more than an ad hoc approach. The key is to use a good supplier with SEMA or FEM approved products with all the required technical data alongside installers armed with the correct accreditations.
Rapid Racking T: 01285 686868
www.rapidracking.com
/ FACTORYEQUIPMENT
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