A quick guide to rack selection

Preface

In today’s rapidly developing world of manufacturing, it is not difficult to see how many new racking suppliers pop up around the globe, especially in China. There are literally hundreds of factories in China at present all producing pallet racking and boasting that their product meets the latest FEM & EN directives. All this comes with of course very attractive prices, while at the same time luring the customer into a false sense of security that the product is of high standard by having glossy brochures and nice looking websites.

Asia has seen a proliferation of pallet racking manufacturers, most of which are either copy or local home made designs with no association with multi national manufacturers. In Asia there still is unfortunately a lack of specialists who are capable of accurately testing or using this test to determine Uniformly Safe Working Loads (USWL).

It is due to this that our company has felt the need to write this brief document in as plain language as possible, so as to aid our customers in comparing correctly and make an informative decision on their long term investment and safety.

Why FEM and EN standards are so important

In today’s market with land costs rising it is not unusual to see selective pallet racking with top beams above 10m and Narrow aisle operations above 14m. Whilst most operators are very aware of beam deflection which is easily visible, regrettably insufficient attention is given to the strength design and safe weight loading of the frame which can take up to 7-8 times a pair of beam loads.

Make no mistake; pallet racking is a dangerous affair. Lives are at risk on a daily basis during operation hours with forklift drivers negotiating tight aisles, turning into and out of the rack with considerable speed and carrying heavy loads.

FEM regulations have been adopted as the Industry standard; these standards are now being adapted to suit all Euro Norm standards to be known as the CEN EN (European committee of standardization) which in 2009 are scheduled to be adopted through out the European Community, and will replace the FEM 10.02.02.

For more information please visit www.cen.eu. Companies failing to meet these standards will not be allowed to sell into the EC.

With this in mind it is of paramount importance to ensure that the offered system does indeed meet these standards and directives as dictated by CEN. The standards affecting pallet racking are:

• EN 15635: Application and maintenance of storage equipment
• EN 15620: Tolerances, deformations and clearances
• EN 15629: Specification of storage equipment.

All pallet racking manufacturers should adhere to these standards and they should have proof that they do so. Usually, a certificate like the one in Appendix A should be requested so that there is proof that indeed the product is compliant. Bear in mind that the certificate should be issued by an independent body.

Don’t be afraid to ask for these certificates as accepting that the product is FEM compliant because it says so in their literature could prove a regrettable decision.

What to look out for in selecting a pallet racking system

Usually when a client is presented with a quotation they look at the following (usually in this order:

1. Cost
2. Capacities
3. Beam deflection

All racking manufacturers can claim that their bay load can take X tons and that their pair of beams can take X tons; but there is more to it than that.

In our opinion, the following points should be taken into account:

Company history and references

• Proof of FEM tests
• Grade of steel used
• Yield point (dependant on grade of steel) – denoted as YP
• Tensile strength (dependant on grade of steel)
• Mid point beam deflection
• Safety factor
• Connectors
• Powder coating standards
• Sections of the beams and frames
• Frame & beam capacity loading tables
• Seismic bracings

We will explain each point individually

Supplier history and references

Supplier pedigree is very important as is a list of references both internationally and in your country. Ask to see references of installations, a customer list and where appropriate, a case study.

A company with an established history will guarantee you spare parts for your future extensions as it will continue to be in operation. Will a small Chinese supplier be around in 3 years time? Can you sue them if you find out that indeed they haven’t adhered to FEM standards and a collapse has occurred, or that they have been using lead in their paint? Do they provide product or public liability insurance?

Bear in mind that it is impossible to sue companies in China – just look at the latest toys case with lead paint poisoning all of our children with Mattel products; all Mattel could do was to withdraw their contracts.

Proof of FEM tests

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Whilst many companies claim to conform to these and all other published standards, the fact is they have never had their product tested. Any testing is accompanied by sets of photographs’ showing detailing the various tests with graphs and reports. If the product has been tested then the reports / photographs are available. If a company can not produce this proof then draw your own conclusions!

Grade of steel

One of the most important elements often overlooked regrettably is the raw material itself. Rolling pallet racking requires little expertise and can often be done at a low investment meaning that more and more companies are jumping on the bandwagon.

SS400 steel grade for example is widely available and can be purchased on the spot in standard coil widths.

Frames on the other hand require steel produced to far higher standards than beams. In some countries, these steels are not readily available and have to be ordered in minimum quantities (SS490 has to be ordered on a 3-month lead-time in minimum quantities of 200-500mt), thereby forcing local manufacturers to use lower grade steel with lower yield points and tensile strengths (we will explain these 2 items further down).

All steel grades should comply with the JISG 3101 standard.

Don’t be fooled by some manufacturer’s samples being larger/thicker than another’s, and thinking that it must be a stronger product. This is often done to compensate for the fact that the steel is of lower quality. Most manufacturers in China use SS200 mild steel, so make sure you ask and challenge that the stated material is indeed the one used.

Yield point

All metals have an elasticity property, meaning that if a force is applied on a metal bar for example, it will deform and then return to its original position when that force is retracted. The Yield point is the amount of force that will cause the material to deform beyond the point of its ability to return, thereby causing a permanent deformation. It is usually measured in N/mm2 (Newtons/mm2)

The steel grade should dictate this value.

See figure below for an illustration.

Picture 2

Tensile strength

Tensile strength is the property defining the permanent deformation of the material when a stretching force is applied. Again the steel grade should dictate this value and has the same units as the Yield point. See figure below for an illustration.

Picture 3

Midpoint beam deflection

The maximum mid point deflection of a beam in accordance to EN 15620 or FEM 10.02.02 should not exceed 1/200 of the beam length. This means that the beam deflection from the horizontal position is allowed to deflect by 2700/200 = 13.5mm when under 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”.

Ensure that this is not a greater than 1/200 as that would give a higher deflection than the EN allowance dictates; it would also show that the beam capacity is higher when in fact there is more overloading. Proper charts should indicate capacities at defined deflections.

See figure below for illustration:

Picture 4

Safety factor

Safety factor is applied to ensure the safety of the installation, and in accordance to FEM 10.02.02 this value is 1:1.55, i.e. 55% on system and 92% on yield calculated to 2nd order analysis.

The published safety factor in China is 30% overload to 1st order analysis, thereby not EN compliant and many manufacturers (even European ones manufacturing in China) lower their factor to be more competitive pricewise.

Again, make sure you get proof that the product is indeed FEM tested and is not just claimed. It could be that the product is only suitable for the Chinese market and not the European one.

If you have a cheap quote from a European manufacturer, it is most likely that the product is now made in China for the Chinese market and that it should not be exported to Europe.

Why do we need such a high safety factor? Surely this will inflate the cost of the system?

Yes but consider what happens daily in your warehouse, Mechanical Equipment weighing up to 4,000kg with load and driver moving at speeds in excess of 10kmph, negotiating aisle of between 3-4m doing 90o turns lifting loads of 1000kg to over 10m with some times un trained or qualified drivers, sound familiar?

Accidents do happen! Sometimes pallets are broken, in poor condition or are not really designed for use in pallet racking and falls. What happens if the rack has little or no safety factor? Then it results in a cross aisle collapse which can trigger a domino collapse through the warehouse bringing down all the racks.

Connectors

Picture 190

The fixitivity of the end connectors is a critical feature to the calculation of the loading tables. Beams with good connectivity to the post will help support damaged uprights’ until racks can be safely off load and repaired. Look for 5 pin (50mm pitch) connectors which is what the European manufacturer’s are moving towards now, in contrast with the standard Chinese 3 pin connector at a 75mm pitch which will twist/rotate under load.

Powder coating standards

Picture 191

Powder coating is another area to question in that most Chinese manufacturers use high lead paint or powder in order to give the product a shiny finish. This would not be accepted in a warehouse where the storage of food, beverages and pharmaceuticals are present, as every time the pallet is scraped over the beam, small particles of lead are sprinkled over the pallets below.

Ensure the supplier uses lead-free powder coating.

Sections of the beams and frames

Picture 193

Ask the supplier for all the various post and beam sizes to see the variety of loading capabilities. Even bracing and footplate sizes are important as they can add to the overall system strength considerably. All the various sizes should be depicted in their loading charts for you to make a comparison between suppliers.

For example if one supplier’s beam is 125mm high and claims a load of 3.6 tons per pair, and another needs 140mm beam to achieve the same load, ask yourself why. It is likely that the steel is of lower grade.

Compare frame loads carefully in relation to the position of the 1st beam from the ground. The section of the 1st beam level is also critical to the frame load; the bigger the section the higher the capacity. We have seen charts that do not detail the various loads in relation to the 1st beam level size; only its height. In which case you should ask the question, what beam section is this loading referring to?

Frame & beam capacity loading tables

This is always an interesting question; how do manufacturers establish their loading charts?

Loading tables should be a result of FEM compliant testing by a qualified independent body. The loads are then calculated using 2nd order analysis by use of a highly complex procedure which requires a special computer program.

This stresses again the point that you should ask the supplier for a FEM proof certificate.

An example loading table is illustrated in Appendix B.

Seismic bracings

Many manufacturers apply back bracing and classify this as seismic bracing. Back bracing is applied by many manufacturers to increase the rigidity of the system but this by no means is a result of a seismic analysis. Seismic bracings must be bolted to the ground otherwise it is simple back bracing. If they are not then you can rest assured that the structure is not seismic!

Seismic design should be accompanied by proof of analysis and tests along with a certificate specifying that the design can perform under earthquake conditions.

Seismic design is extremely complicated and requires a structural engineer with complex software to perform the calculations. Proof of these calculations should be available if requested.

For a seismic structure, ask for a certificate that shows as a minimum the following data:

• Regulation used (Earthquake standard)
• Amax or Z factor (the ground acceleration in the event of an earthquake which is given by the local geological institute or can be acquired by the civil engineer of the building)
• The soil type of the ground underneath the building (classified by letters A-E)

Summary

We hope to have raised your awareness of what to look out for when considering the purchase of pallet racking. It is easy to be tempted by a supplier who offers a stupidly low price and not take into account all the above points that will constitute a safe working environment for you and your employees.

Spend time investigating the technical details and comparing like for like without disqualifying quotes based on price. Question the supplier and ask for proof of what they are claiming. If they can’t provide proof on EN compliancy then walk away as it is likely that it is not. EN compliancy is a costly and complex process and is not acquired that easily.

Research and product testing on a regular basis in order to ensure that the product is always inline with the latest directives is of paramount importance, which also add to the overall product cost.

Remember… the racking business especially on high volume projects is a low margin one, and if one supplier’s price is higher than the other’s there is usually a very good reason for it.

On a last note, remember that companies showing you ISO 9001 certificates doesn’t mean that their product is safe; ISO compliance is the documentation of procedures and processes and has nothing to do with safety.

Simply put, you get what you pay for.

Appendix A

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Appendix B

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Appendix C

Technical data for SSI Schafer

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About SSI Schaefer

Company pedigree is very important and it is not hard to see that SSI Schaefer is one with the longest life and largest turnover on the globe, having huge global installations. Schaefer in Europe have been in operation for over 60 years now and their Middle East and Asia business for 25 years running. This long service as well as the constant high global turnover speaks for itself.

Steel grades

Yield Point

*Structural calculations use a YP of 270N/mm2 for beams and 390N/mm2 for frames

Tensile strength

FEM Compliance

Schaefer Interlock 600 (I600) has been tested Internationally twice, I75 in 1991 by Frank Neal at Brookes University Oxford to SEMA by Dr Godley, and then in 2005 by Heinz Niedermuller and by Dr Moell in Germany and then finally at Greenwich University London UK to FEM 10.02.02.

Schaefer were the first company in Asia to receive full FEM 10.02.02 accreditation for the design of pallet racking systems (see appendix A).

Powder coating

Schaefer use high quality AKZO Nobel lead –free powder coating for their paint process.

Connectors

I600 has a very tight fit to the post (5 pin) providing maximum rigidity or “spring’ to the connection.