Storage Rack Failure

Preventing storage rack failure should be a priority for any facility using these systems. A routine inspection program should be instituted using individuals competent in this subject.

Following are four main causes for rack failure but should not be construed as the only causes.

Operator damage through errors made while operating lift equipment seem to be the most common reason cited. Excessive, repetitive damage that can be directly attributed to this cause in any facility should be cause for alarm and the immediate institution of further training, monitoring, and disciplinary action.

Before any disciplinary action is taken, it would be wise to check for poor design. Most rack purchased today through reputable channels will also be in compliance with RMI (Rack Manufacturers Institute) standards. These standards demand a high level of design to be in compliance. Poor design of the layout and beam/frame spacing may be causing operator induced damage. Many designers and owners, in an attempt to maximize the cube will lay a system out to minimum requirements. Minimum aisle size for a given fork truck means the operator better be perfect and in a high thru-put environment, that’s unlikely to happen. Within the rack structure there’s vertical lift-off; 6” between top of load and bottom of next beam is a good rule of thumb. Horizontal spacing; 3” spacing may be okay but 4” is better. Pallet overhang; 2” overhang front and back allows for a wider frame base but 3” overhang front and back allows for more operator miscalculation. Wire decking or front to back supports also allow more error.

Installation errors can range from inadequate anchoring (or no anchoring) to no leveling and squaring. A professional crew will not leave a site like this.

Floor problems should be noted and corrected prior to installation and if noticed at a later time, steps taken to correct and rack reinstalled.

A visual inspection on an ongoing basis by operators and supervision should key in on the following.

Dented, kinked or twisted uprights are an obvious sign of forklift damage and in some facilities seem to “have been there” usually for some time. Will it take one more “hit” or seemingly last forever? Replace these as soon as possible. Damaged struts within a structure will normally be associated with damaged posts and are an obvious replacement. End of aisle struts may be damaged alone as they are exposed to traffic unless guarded. These are critical structural elements and should be replaced and consideration given to guarding.

Any damaged or kinked beam should be replaced. A beam appearing to have a severe bow should be measured from floor at ends and at middle. RMI standards

State that beams are typically designed to accommodate vertical deflections that do not exceed 1/180 of the horizontal beam length as measured with respect to the ends of the beams.

The ANSI/RMI Specification shows the maximum out-of-plumb ratio for a loaded rack column as 1/2” per 10 feet of height.