Our first question this month asks about the practice of bolting beams to uprights and if this is should be considered “Good Practice”. Then we have a question that asks if it is OK to erect racking flat against a wall, or if it a gap should be allowed.
Bolting Beams
Q. A US parent company wants all subsidiaries to bolt their beams to the uprights, can you let me have an official SEMA response please.
A. SEMA guidance is not to bolt beams into racking uprights unless the risk assessment for the particular installation identifies a clear benefit in so doing.
Generally the SEMA experience is that a bolted connection is often too strong, in that when an accident happens and the full power of a truck is applied to the joint instead of shearing the pin and then having a single beam dislodged, the dislodgement still happens however the bolted connection then tears the material in the upright which in turn causes the upright to collapse resulting in a complete double bay coming down. Unfortunately this is often not the end of things as there are now a lot of beams, dislodged at the collapsed upright end which are rotating at the other end causing similar upright damage in the adjacent uprights which then also collapse. The net result is a progressive collapse situation going down a complete run in an aisle!!
Normally in these situations the beam connector lock is designed to act as a fuse allowing beams to dislodge at slightly over 500 kg uplift before more serious damage takes place to the upright.
There are exceptions to this rule in that front beams in pallet live storage installations need to be bolted in to accept the high buffer forces involved. Similarly if a beam is used as a horizontal member in a bracing system then it needs to be bolted and also if the rack is built in a seismic zone this may also have to be considered depending on the bracing used in the system. Building codes in the UK however do not require seismic effects to be taken into account so for the vast majority of racking, manufacturer-provided locking pins would be all that is required and the addition of bolts could be seen to provide a more dangerous structure.
SEMA would therefore support the view that bolts are not required.
As a slight aside we would also comment that on the rare occasions when we do bolt in place of locking pins for various reasons we would consider a 6 mm, 1/4 inch gutter bolt would be all that was required again to make sure that the joint could split apart if necessary. It would seem from your correspondence that you are using 1/2 inch diameter bolts which we would consider much too strong for this application.
This all boils down to your specific risk assessment and if you can prove that the potential hazards of even a single beam coming out are so great as to be unacceptable in your warehouses, then perhaps this can be done. We would respectfully suggest a detailed discussion with your insurers on this matter however.
Minimum gap required
Q. Could you please advise if it is possible to place racking flush against a warehouse wall or should a minimum gap be required.
A. The short answer is that it is possible however it may not be desirable!
Assuming your racking is designed to store pallets then it will have been specified for a certain pallet overhang at both front and back of the racking. If it has been designed for 4-way entry pallets then this will be 50 mm in both cases and if a 2-way entry rather more than this.
You will need this dimension plus a clearance if you are asking truck drivers to position the pallets without hitting the wall behind which could end up destroying the wall as plainly normal walls are not designed to take truck impact. Having done a calculation to establish what clearance is required for the worst possible pallet positioning that an errant truck driver could achieve without the pallet hitting the wall you then need to add any goods overhang on the pallet and also need to consider any lack of verticality of the pallet loads during normal operations.
Finally you need to consider air circulation round the goods and the construction of the wall itself. If this is an external wall of non-cavity construction there will be a tendency to draw quite a lot of dampness through the wall which can result in the racking and the stored goods also becoming damp and leads to the formation rust on the racking, various forms of mould on the goods and on the wall itself. Good ventilation is required if this is to be avoided.
If you are intending to deck out the racking and use it as hand loaded shelving then some of the above will not be applicable however air circulation certainly will still be an issue and the requirement will vary depending on the age of construction, condition and type of wall.
SEMA Annual Safety Conference
The 2014 SEMA Safety Conference has been scheduled for 6th November; at the National Motorcycle Museum, Solihull.
SEMA Rack Safety Awareness and Inspection Courses
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.
SEMA Approved Rack Inspectors Qualification
This qualification is aimed at professionals who conduct rack surveys as an integral and significant part of their duties.
SEMA USERS Club
SEMA runs a USERS Club designed to be of benefit to purchasers and users of storage equipment. Members receive newsletters, access to specialised events and discounted rates on publications and codes of practice.
Comments are closed.