Our first question this month involves Safe Working Load notices and their placement and frequency. Then we have a question on the validity of securing frames to the infrastructure of a building and whether this acts to prevent a possible collapse.
Load notice location
Q. We recently had our bi-annual Health & Safety audit where it was highlighted that our racking load notices were not displayed in each bay as required. We were of the opinion that load notices are not required in each bay but per run. Could you please clarify what the requirement for load notice placement is.
A. There is unfortunately not a straight answer to your question, I am afraid “it all depends.”
The legal requirement is to provide users of the racking system with enough information that they can safely use the equipment without danger to themselves or to others in the vicinity.
If therefore you had a warehouse where all the racking was of the same duty and it had all the beams at the same levels with only a single entrance for trucks and drivers then as the carrying capacity of everything would be identical it is arguable that only a single sign would be needed at the entrance to the warehouse so the drivers were aware of the carrying capacity of all the locations in this warehouse.
This is unlikely to be the case and it is assumed that you have specific beam positions in specific runs of racking. In this case it is perfectly normal to place a single sign on the end of a run and truck drivers will appreciate that this sign refers to all the racking in that run.
If in a single run there are two or more distinct rack profiles then often several signs are attached to the end of the run giving information on the capacity of each profile in that run.
If there are more than two profiles then there is a danger of information overload of the truck drivers trying to remember the capacity of each profile and in this case often the supplier will calculate a ‘worst case’ loading and will place that on a single sign on the end of the run. It is not usual practice to place a sign on each bay in a run though there is nothing preventing this.
It can all get quite complex however as long a you remember that the whole point of the signs is to ensure that there is clear information for the user to ensure that he / she can understand how to use the system safely without the danger of overload then you are covering the requirement.
The ties that bind
Q. I have a client who is insists on securing frames to the main infrastructure of the building to in his view “prevent collapse”. I can see nothing in the guides or ACOPs which would give a definitive answer what would be SEMA’s advice on this?
A. There are some basic geometrical rules based on the height to width ratio that are used within the SEMA codes. If the height of the rack to the top beam level divided by the frame depth is less than 10 and each rack foot is bolted to the floor then the rack can be designed as free standing. So for example a rack with a beam height of 10m and frame depth of 1.1m has ratio of 9.09. If however this ratio exceeds 10 then the rack need to be tied to another structure. This is generally achieved by tying to an adjacent run of back to back racking which has run spacers connecting the two runs together. If this is not possible then tying to another rackover the top of the aisle may be a possibility or another option might be to tie back to the building structure.
The Storage Equipment Manufacturer’s Association User’s Guide for Pallet Racking in section 7.2 provides guidance as follows
7.20 Ties to Buildings
Restraining ties to the building structure are not recommended. However, if ties are fitted, the User should confirm with the Supplier that the ties have been correctly designed and installed.
When such ties are required, checks should be made that the loads transmitted through the ties are within the safe capacity of the building structure and also that of the racking.
This advice is essentially repeated in the Health and Safety Executive publication HSG76 Warehouse and Storage a Guide to Health and Safety paragraph 634 where there is a requirement for the building structure to be “proved” that that it has been designed to accommodate the forces from the racking system.
It is not just a case of designing the building for the loads but also the racking designer will need to be made aware of the tie and the forces that may be transmitted in to the racking from when the building naturally moves under loading. The allowable deflections in building design are generally far higher than those used in the design of pallet racking structures.
SEMA is delighted to be working with WLN on the storage Q and A Column. On the WLN website is a list of previously published columns.
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