Two more enquiries this month, the first is looking for advice on the loading of racking and the second looks at Cross beam deflection and what is permitted.
Loading of racking
Q. Could you give me some advice on the loading of racking? Am I correct in saying that the design of the racking is to fit with the design of pallets, to enable the pallet blocks to take the weight against the racking beams and not the pallet struts taking the weight on the racking beams.
A. Yes, you are correct that the pallet blocks should be supported on the beams of pallet racking and it is not acceptable to have the load supported by the bottom boards of the pallet acting in bending.
Appendix II of the SEMA Code of Practice for the Use of Static Pallet Racking gives some industry guidance on recommended frame dimensions required for particular pallet sizes.
For instance with a four way entry 1200 x 1000 pallet being stored with its 1200 side facing the aisle and the 1000 face spanning the beams of the racking this would require a 900 end frame to support it. This would in effect mean that it was designed to have 50mm overhang over the front and back beams in its optimum position and ensure that all corner blocks were supported adequately. If the pallet is accidentally placed such that the front face of the pallet is flush with the front beam (which is probably the worst positioning that can normally be achieved) then this will mean that there is a 100mm overhang at the rear though the corner block with most reputable pallets will be large enough that this is still be supported on the racking beam.
We hope that this advice is of help and if you need further information we would commend the SEMA Code of Practice on the Use of Pallet Racking as a very useful document.
Cross – beam deflection
Q We have recently erected racking & would like to confirm the maximum permitted cross-beam deflection on 1 tonne beams.
A. Generally beam deflection under maximum safe working load will not exceed ‘Span/200’ as recommended in the SEMA Code of Practice.
In other words if you have a 2700mm beam this will give you a maximum allowable 13.5mm deflection.
A deflection of this magnitude is quite noticeable when the lower levels of beams are viewed along the run of the aisle. However this level of deflection is the one that is allowed in most of the codes of practice world wide and the designer will have taken this into account when designing the product and will have ensured that an appropriate level of safety is still present within the racking.
Can we suggest that when checking deflection you do so from a taut string-line attached to the racking uprights just below the beam rather than measuring from the floor which itself might not be level.
It is of course open to any purchaser of racking equipment to specify tighter deflection tolerances which can be done at increased cost and such tighter standards are sometimes required for the reliable operation of automated equipment. However for run of the mill racking the ‘Span/200’ deflection limit is usually adequate.
SEMA is delighted to be working with WLN on the storage Question and Answer Column which is published in WLN on a monthly basis. On the WLN website is a list of previously published columns which we hope you find useful.
Please note that SEMA Users Club members also have access to a comprehensive range of additional storage related questions and answers.
For more information, please go to www.sema.org.uk
SEMA Technical Enquiries
We hope you find the above articles, and those in previous editions, interesting. If you have a query send it to us by fax or email and we will do our best to have it answered by one of our technical experts.
SEMA Rack Safety Awareness and Inspection Courses
SEMA runs a one-day safety course on Rack Safety Awareness and Inspection. These courses are aimed at end users, giving an in-depth look at the need for inspections, how to conduct an assessment and what actions to take when this is completed. These courses are normally held at the SEMA headquarters but arrangements can be made to hold them at the delegates’ premises.
SEMA Approved Rack Inspectors Qualification
This qualification is aimed at professionals who conduct rack surveys as an integral and significant part of their duties. It involves delegates in undertaking an in-depth SEMA Course, together with an examination and practical assessment. CPD will be an important part of the qualification, demonstrating to end users that SEMA Approved Inspectors maintain a high professional standard.
SEMA Publications
SEMA publishes a number of documents including Codes of Practice, ‘Guides’ and European documents – all of which are available from our Office. For further information contact SEMA or visit our website, and click on ‘Codes of Practice’.
SEMA USERS Club
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For more info, go to www.sema.org.uk
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