Among the most frequently asked questions I get from my customers are: “What is the difference between a point load and uniformly distributed load (UDL)? And why does it matter?” Distributors are struggling with this question, as their end customer is claiming that the competition is offering standard mesh decks which, as long as they are heavy enough, will hold the point load …
In general, I try to explain the difference over the phone: that involves a lot of waving with my hands. Our sales director Kristin always has to point out to me that people actually do not see me through the phone … so maybe it is time to write something about it.
UDL is any static load which is evenly distributed over the full surface of the mesh deck. So its magnitude remains uniform throughout the length of the beam. However, if there is a pallet smaller than the beams, a pallet that is placed in the middle of it, this rule no longer counts.
Welcome to the world of point load! There are different types of load layouts: line, concentrated and point load. If you want to know the difference I suggest you google it, otherwise this blog risks to become too boring.
I will concentrate on point loads as uneven weight concentrations in opposition to UDL. This means inconsistent weight transfers where one part of the contact surface has higher pressure than another. This can be due to the pallet skids or due to the type of goods stored, such as a roll of paper. All this weight is heavily concentrated at these points and can thus cause severe mesh sag, making the stored product dangerously unbalanced and unsupported.
How to solve this? Properly designed mesh decks compensate for high and low weight transfer contact. The location of the support bars, the addition of the extra support bars and the thickness of the wire can all counteract point loading. But this needs to be calculated, and you might be wondering: “hmm, this sounds complicated, I might need some engineers to help me?”. To simplify your daily life, we have broken point load down into different scenarios, such as pallets partly on the beams, pallets with two skids, boxes … and it is no longer rocket science! Make your pick and the system calculates if it is possible to make a mesh deck.
When dealing with point loads, one first has to calculate if it is possible to make a mesh deck for it. At that moment, one has to compare the price of that mesh deck with a grating and no longer with a standard mesh deck. Gratings are one of the most heavy-duty options. They can be manufactured to meet nearly any loading requirement. They handle point loads very well, and can have a very high capacity. But gratings are one of the most expensive decking options. So it is important to compare the right prices, apples are apples, pears are pears.
It’s really no mystery why there is so much discussion about the definition of UDL in general and point loads in specific. In all aspects of the material handling industry, competition drives the market. Often price is the key determinant in securing a sales order. And what better way to reduce the cost of a deck than by eliminating some material. The end-user truly gets what she/he pays for when buying a wire deck.
That is why the introduction of ANSI as a safety standard is important. It makes products comparable with one another. Unfortunately, the two-times safety factor before structural collapse that is built into the ANSI standard, makes it tempting to bend the rules a little.
The laws of physics cannot be changed, and they determine the rated capacity a given deck will yield when loaded. So, in some cases people ignoring point load may be lucky when buying a standard mesh deck. Unfortunately, in other cases we often see pictures of bending mesh decks, and in the worst case of collapsing mesh decks – with pleads to help solve the problem. So the question is: are you willing to take this risk – or do you even gamble with safety and consider this fake news?