The first question this month looks at wrap around guards and asks whether these can hide potential hazards. Our second question asks if there is a formula for calculating column load for cantilever racking.
Wrap Around Guards on Uprights – do they just mask the hazard?
Q. There is currently a trend towards wrap around plastic rack protectors. I have some concerns that these can hide damage. Does SEMA have a view?
A. SEMA are aware of the problems with this type of upright protector and we do discuss these items very thoroughly on the SARI (SEMA Approved Rack Inspectors) course as it is an ongoing problem for rack inspectors who need to remove these to inspect the upright behind the protection.
It is our experience that substantial damage to the upright can be missed if attempts are made to inspect the uprights fitted with such protectors for damage from the inside (i.e. down the throat of the upright). The protectors must therefore be removed and replaced as part of the inspection which slows up the process considerably. This can of course be made worse if the protectors are semi- permanently secured by cable ties rather than Velcro or other temporary fixings as is the case with some types. In this case the inspector would need to discuss and negotiate the situation with the client, as he probably would not carry spare cable ties of the correct size to re-secure these and would probably not have included sufficient time in his estimate for the inspection to carry out this work either!
SEMA believe that in the correct circumstances and with the correct routines of inspection management in place they can be used very satisfactorily. Warehouse management should train fork lift drivers to remove protectors and inspect uprights when an apparently small impact occurs as they will not hear the loud bang that normally accompanies an impact. In addition supervisors should remove a few of these protectors during their weekly inspection of the racking on a random basis to ensure the severe repetitive damage does not exist unnoticed. Finally it needs to be a requirement that the biannual inspection should include the removal and the inspection of the upright behind the protector.
In other circumstances where these procedures are not followed it is possible for serious damage to exist that is hidden behind the protector giving the warehouse staff and management a false impression of the quality of the racking and the standard of driving that is occurring in that particular warehouse.
The final comment which applies to these and all other protectors is if these have been fitted “post installation of the racking” the physical thickness of protection would not have been considered in the calculations of bay and aisle widths. This can mean it is possible to create operational problems by reducing clearances in what might already be a “tight” aisle by the fitting of the protectors in the first place.
In summary they can and do work satisfactorily however they need to be considered on a case by case basis and are not something that can be fitted and forgotten.
Calculating the Column Load for Cantilever Racking
Q. Is there a formula for calculating the column load on cantilever racking, and would it make a difference if they where bridged?
A. Regrettably there is no simplistic formula. Cantilever racking upright design is a relatively complex procedure and is generally analysed by structural engineers in accordance with the British Standard Steel Design Code. We would suggest you either contact the original supplier or an Independent Structural Engineer who will be able to survey your racking and determine the load carrying capacity.
SEMA is delighted to be working with WLN on the storage Question and Answer Column which is published on a monthly basis.
For more information, please go to www.sema.org.uk