SOURCE: Rack Users Guide 2018/2019
In a global supply environment, numerous rack manufacturers offer many supply options with suppliers throughout the world all claiming to meet the latest standards. The common standard we work to in South Africa is the European standard – which has largely superseded the FEM & SEMA standards.
Why standards are important
Due to the increase in land and building costs, many modern warehouse facilities have top beams well above 10m – and with reach trucks approaching 12.5m lift and turret trucks approaching 17m, design is becoming more and more complex.
Added to this, the racking business is highly competitive, and many companies are forced to cut their designs “to the bone” to be price competitive.
Badly designed racking can be extremely dangerous and there are many local and international racking suppliers who provide designs that are not safe!
Ideally, pallet racking manufacturers should adhere to these standards and they should have proof that they do so. This implies issuing an appropriate certificate of compliance.
When specifying a rack, the following are the common client requirement:
- Height of beams
- Pallet type and mass
- Aisle widths
The manufacturer should then take into account:
- Operating environment
- Grade of steel used
- Yield point (dependent on the grade of steel)
- Tensile strength (dependent on the grade of steel)
- Beam type, strength, deflection
- Frame type, strength, rigidity
- Safety factors
- Paint standards
- Seismic bracing (if any)
- Strength in case of collision
Proof of EAN/FEM tests
Many suppliers will claim to meet EAN/FEM standards, but many have not had their product tested by an appropriate approved authority! If the product has not been tested, you should think twice before buying it.
NOTE: Because companies have an ISO9001 certification doesn’t necessarily mean that their product is safe; ISO compliance is the documentation of procedures and processes and has nothing to do with safety.
So how do we measure rack performance?
The maximum mid-point deflection of a beam in accordance with EN 15620 of FEW 10.02.02 should not exceed 1/200 of the beam length. For example: for a 2700mm long beam, the deflection from the horizontal position is allowed to deflect by 2700/200 – 13.5mm when under full load, thus returning to its original position when the load is removed.
So when the beams are loaded you should be able to see a slight “bending”. All you need to do is stretch some nylon across the connectors at the beam tops and measure the deflection under full load.
As an added safety factor in South Africa, we often recommend a maximum deflection of 1:250 – especially if the usage of the racking is “heavy” or if the user is unsure of the specifications provided.
FEM 10.02.02 / EAN calls for a safety factor and this value is 1:1.55, ie, 55% on the system and 92% on yield calculated to 2nd order analysis. This means if you store pallets weighing 1000kg (maximum), the pallet racking supplier should design for pallets having a mass of 1550kg.
The publisher safety factor in China is 30% overload to 1st order analysis, thereby not EN compliant and many manufacturers (even European companies manufacturing in China) lower their factor to be more competitive price-wise. This, in our opinion, is unacceptable for South African Environments.
In South Africa, we generally recommend a safety factor of 1:1.6 (60% safety factor). If the rack is loaded to 1.6 times its rated capacity, there should be no permanent plastic deformation of the beams.
We also strongly recommend that systems, where the bottom levels carry heavier loads (variable loads across racking networks), are only used where an extremely high level of discipline is in place and where the warehouse management system controls weight and pallet movement. This is because there is a danger that staff will override the limits and place heavy products in the wrong locations.
Sections of beams and frames
Clearly, the size of the frame and beam is critical to the load-carrying capacity. While we all want beam depths as low as possible (giving more operational space), the beam depth forms a critical component of the rack. The beam depth is also highly influenced by the grade of steel used.
Frame loads are highly influenced by the position of the 1st beam from the ground. This is why it is important to define the position of the first beam and ensure that the user does not “play around” without checking with the manufacturer regarding the effect on the rack-carrying capacity.
Loading of frames and beams should be a result of EAN/FEM compliant testing by a qualified independent body.
Pallet Racking can be extremely dangerous. To ensure safety it needs to properly be:
The user should spend time investigating the technical details and comparing like for like – and not only focus on price. Make sure the rack supplier can actually prove what they are claiming. If they can’t prove EN (or similar) compliancy, then walk away!