Bolted Frames Verses Welded Frames
March 21, 2012
Unquestionably, Pallet Racks take abuse. They are constantly being hit with forklifts when storing and removing pallets. Not to mention the other human errors that add to the standard wear and tear of a shelving unit, which at some point must be repaired. Bolted Rack is easier and quicker to repair than a Welded Pallet Rack System. "Selling bolted to a welded market is all about serviceability", Demke says, adding that in most cases, "it is easier to service a bolted frame if it's damaged," source InterlakeMecalux. When a pallet rack is welded the damaged pieces must be torched or cut off. The loads are removed in either case welded or bolted rack, then replaced with a repair kit, which is comprised of a bolted frame. Not having to remove the beam is nice, however it does not add to the overall efficiency of the repair, and as in most facilities they will not allow repairs to a welded rack during business hours because the area must be shut down during the cutting process, for the protection of the employees and customers.
Without constant attention, the nuts in the bolted rack will unthread and the structure will fall. Greg Hajdus, structural engineer with Interlake Mecalux says, "I've heard many times that if you have a bolted frame, every once in a while you will have to go in and tighten the bolts, that's not true he states, When you've got a bolted frame, when it's assembled correctly, you don't have to do anything to it. Ever," (source InterlakeMecalux).
Even after the time and space is allowed for a weld to be repaired, the weld can still be faulty. It could potentially be undercut, given too little or too much heat, and a lack of added flux core. These are all human errors common to bad welds and broken welded rack. The problems a customer has with welded rack and welder fluency do not usually exist with bolted selective shelving. Every piece is machine manufactures an passed through strict quality testing. In addition, the restraint provided by bolts and welds is different. Welding a brace provides the rack with a certain amount of end restraint. The more end restraint, the more carrying capacity of the rack. This in turn reduces the brace's buckling length which enhances the restraint. In compairison, if a weld, applied by a human, is faulty, the rack's capacity could be reduced to as little as zero, and perhaps with the customer realizing it. These same results would occur for bolted rack with faulty connections as welded rack, however the risk of it happening is much lower. Bolted frames have well defined and highly controlled buckling lengths (source InterlakeMecalux.com).