Pallet rack safety and compliance are essential for efficient warehouse operations. As a recognized leader in the field, the Rack Manufacturer’s Institute (RMI) sets the standard for industrial steel storage racks through its key engineering document, ANSI MH16.1-2023, “Design, Testing, and Utilization of Industrial Steel Storage Racks." Damotech, a proud Associate Member of RMI, leverages this expertise to provide insights into pallet rack repair and safe operational practices.
This blog explores paraphrased excerpts and key takeaways from ANSI MH16.1-2023, offering practical guidance for maintaining rack integrity and safety. While adherence to the standard is voluntary and not legally binding, it provides invaluable technical guidelines to enhance your operations. Learn how this trusted resource can help ensure the safety and efficiency of your storage systems.
4. Integrity of Rack Installation
4.1 Owner Maintenance
Owners shall maintain the structural integrity of the installed rack system by assuring proper operational, housekeeping, and maintenance procedures, including, but not limited to, the following:
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Regularly inspect for damage. If damage is found, immediately isolate the affected area. Have a storage rack design professional evaluate the damage and unload, replace, or repair, if directed by the professional, any damaged columns, beams, or other structural components to restore the system to at least its original design capacity.
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Require all pallets to be maintained in good safe operating condition.
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Ensure that pallets are correctly placed onto pallet load support members in a properly stacked and stable position.
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Ensure that all goods stored on each pallet are properly stacked and stable.
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Prohibit double stacking of any pallet position, including the topmost position, unless the rack system is specifically designed for such loading.
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Ensure that the racks are not modified or rearranged outside the original design configurations per 4.4 or in a manner that might invalidate the plaque information per 4.5.
4.2 Column Base Plates and Anchors
The bottom of all columns shall be furnished with column base plates, as specified in Section 11.1. All rack columns shall be anchored to the floor with anchor bolts, designed following Section 11.3 to resist all applicable forces as described in Section 7.1.
4.4 Repair or replacement of damaged rack systems or components
Upon any visible damage, the pertinent portions of the rack shall be immediately isolated by the user until the damaged portions are evaluated by a storage rack design professional. Before allowing the rack back into service, the design professional must certify that the rack system and/or the repaired components have been restored to at least their original design capacity.
4.5 Load Plaque
The owner is responsible for displaying in one or more conspicuous locations a permanent plaque(s). Each plaque shall have an area of not less than 50 square inches. Plaques shall show in clear, legible print (a) the maximum permissible unit load and/or maximum uniformly distributed load per level, (b) the average unit load (see Section 7.4.2.2) if applicable, and (c) the maximum total load per bay (see Section 7.2.2).
The unit load is usually a single pallet or container and its contents that are mechanically transported. Storage levels having multiple stacking of unit loads shall be identified. It is the owner's responsibility to ensure that the rack system is not altered so that the plaque information is invalidated.
4.7 Multiple Configurations
If a pallet rack or stacker rack system is designed for more than one storage-level configuration or profile, the load application and rack configuration drawings (see LARCs in Section 4.6) are to include either (a) all the permissible configurations or (b) limitations as to the maximum number of storage levels, the maximum distance between levels, and the maximum distance from the floor to the bottom storage level.
This information is best furnished in table form on the drawings. A notice stating that deviations from the limitations must be evaluated by a storage rack design professional must be included in the conspicuous text on the drawings, or the deviation may impair the safety of the rack installation. If approved, a change shall be added as a permissible configuration on the drawings.
4.10 Out-of-Plumb and Out-of-Straight Limits
4.10.1 Out-of-plumb limit: The maximum top-to-bottom out-of-plumb ratio for a loaded rack column is 1/240 (for example, 1/2" per 10ft [12 mm per 3 m] of height). Columns whose out-of-plumb ratio exceeds this limit should be unloaded and replumbed. Any damaged parts must be repaired or replaced.
4.10.2 Out-of-straight limit: The maximum out-of-straight ratio for a loaded rack column is 1/240 (0.05" per foot or 1/2" per 10ft [12 mm per 3 m] of height. Columns whose out-of-straight ratio exceeds this limit should be unloaded and replumbed. Any damaged parts must be repaired or replaced.
7.4 Earthquake Loads
Earthquake effects and associated lateral forces shall be incorporated into industrial storage rack design when required by applicable building codes. For each such installation, the storage rack shall be designed, manufactured, and installed by such provisions. See Sections 7.4.1 to 7.4.11 for more information.
9.4.3 Beam Locking Device
For storage rack beams and fixed shelves in movable-shelf racks, beams subject to machine loading shall have connection locking devices (or bolts) capable of resisting an upward force of 1,000 lbf (4,450 N) per connection without failure or disengagement.
9.6 Welded-Wire Rack Decking
Where rack decking is utilized to support the load, it shall be designed by ANSI MH26.2.
11.2 Shims
Shims may be used under the base plate to maintain the storage rack's plumbness and/or levelness. The shims shall be made of a material that meets or exceeds the floor's design bearing strength (LRFD) or allowable bearing strength (ASD). The shim size and location under the base plate shall be equal to or greater than the required base plate size and location. The total thickness of a shim stack under a base plate shall not exceed six times the diameter of the largest anchor bolt used in that base.
Shims stacks shall be secure or fastened together in a fashion that can transfer all the shear forces at the base. Bending in the anchor associated with shims or grout under the base plate shall be considered in the design of anchor bolts.
11.3 Anchorage
The anchor bolt design shall be according to ACI 318 Chapter 17. When periodic inspection of the anchor bolt installation is required, the owner or the owner's designated representative shall retain a qualified inspector to conduct the inspection. The inspection shall be limited to the anchors in the main force-resisting system.
12.1.3 Height-to-Depth Ratios
The height-to-depth ratio of a storage rack with straight-column-style frames shall be at most 6 to 1 unless the rack is anchored to resist all forces or braced externally to resist overturning. The height is measured from the floor to the top loaded storage level, and the depth is measured from face to face of the upright column at the floor level.
12.1.4 Loading by Powered Material Handling Equipment
Storage rack, loaded and unloaded by powered handling equipment, that exceeds the 6 to 1 ratio defined above, shall be designed to resist a 350 lbf (1,560-N) side force applied to any single frame at the top loaded storage level. For LRFD design method, the load factor applied to this force shall be 1.6. This force is to be applied to an empty frame and divided into as many frames as are interconnected in the direction of the force. Anchor bolts and base plates will be designed to resist the resulting uplift forces from this applied force.
Frame columns need not be designed for the additional axial load from this force. Unless it can be shown to be unnecessary because of factors such as soil, slab, and frame stiffness, single rows of racks exceeding a height-to-depth ratio of 8 to 1 must be tied externally to the building or cross-aisle to another rack. Stabilizing a single rack with a height-to-depth ratio over 8 to 1 with anchoring alone is only recommended if designed and certified by an engineer.
12.3.3 Posting of Design Loads
The design loads for the floor areas of the rack-supported platforms, pick module walkways, and open areas shall be shown on the LARC drawings. These design loads shall also be displayed in one or more conspicuous locations within the structure, such as at the top and/or bottom of the access stairway or ladder.
Conclusion: How Damotech Can Help
Navigating the complexities of pallet rack safety and compliance with standards like ANSI MH16.1-2023 requires expertise and attention to detail. Damotech is here to help you maintain the structural integrity of your racking systems, ensure compliance with safety regulations, and enhance warehouse operations.
Our team of experts can assess your racks, recommend repairs, or provide long-term solutions. Contact our experts today to discuss your needs and discover how we can support your warehouse's safety and efficiency.
