Jane For the sake of even more clarity, I used the term 'bending equations' to infer that it is perfectly possible to construct a suitable model of this racking system - if the information was to be provided. And to subject the model to suitable analysis of loading and possible modes of failure using a range of known/agreed matematical models/equations. Exactly what analysis, it is not possible to fully detail at the moment. Once again, I totally agree, we do not have enough information to draw any hard and fast conclusions about the SWL or likely mode of failure or which material will fail first (plywood or steel). The point remains it is not beyond the realms of possibility to arrive at an estimate of the SWL using established engineering science techniques.

When I spoke to our insurance lifting gear assessor & another lifting gear company manager, in-house establishment of the SWL was not veiwed as a big complicated issue. All we would need to do was confirm the racks overall condition, establish what the racks were already carrying (and had carried for many years) and set that as the SWL. Whilst also photo/documenting as proof of test. The racks are box steel, welded in an Aerospace engineering environment, no more than 2mtrs high & 1mtr depth, with plywood shelves & sturdy, in fact far more capable than many off the shelf products. Has anyone experience of setting their own SWL in similar circumstance?