RMI’s ANSI MH16.1-2023 Related Excerpts and Paraphrases

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. This document 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: 

1. 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.

2. Require all pallets to be maintained in good safe operating condition. 

3. Ensure that pallets are correctly placed onto pallet load support members in a properly stacked and stable position. 

4. Ensure that all goods stored on each pallet are properly stacked and stable. 

5. Prohibit double stacking of any pallet position, including the topmost position, unless the rack system is specifically designed for such loading. 

6. 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 and LARCs 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 if applicable, (c) the total average load per bay, and (d) the maximum total load per bay. 

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 or both of the following: (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. 

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. 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. 

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.  

Frequently Asked Questions: RMI’s ANSI MH16.1-2023 Standard and Rack Safety

What is ANSI MH16.1-2023, and why is it important?

ANSI MH16.1-2023, titled “Design, Testing, and Utilization of Industrial Steel Storage Racks,” is the current engineering standard published by the Rack Manufacturers Institute (RMI). It establishes comprehensive requirements for designing, testing, installing, maintaining, and using industrial steel storage racks to ensure structural safety and regulatory compliance. The 2023 edition reflects the latest engineering practices and safety research, making it the authoritative reference for rack safety in North America.

What are an owner’s responsibilities under ANSI MH16.1-2023 Section?

Rack owners are responsible for maintaining the structural integrity of their rack systems through proper planning, housekeeping, and maintenance. This includes:

• Regularly inspect racks for damage and isolate any affected area.
• Ensuring that any damage is evaluated, repaired, or replaced by a qualified storage rack professional to restore the original load capacity.
• Maintaining pallets and loads in a stable, properly stacked condition.
• Prohibiting double stacking unless the rack is specifically designed for it.
• Avoiding modifications that would invalidate LARC drawings or load capacity plaques.
• Training staff and monitoring compliance with safety and operational guidelines.

What does ANSI MH16.1-2023 require for column baseplates and anchors?

Every rack column must have a baseplate and be anchored to the floor with bolts to resist all applicable vertical and lateral forces. Proper anchoring is essential to prevent uplift and horizontal movement at the column base.

How should damaged rack components be handled?

When visible damage occurs, the affected rack area must be immediately isolated and removed from service. The area should remain unloaded and cordoned off until a qualified design professional evaluates the damage. The rack may only be returned to service once a qualified engineer certifies that repairs restore the system to its original design capacity. Documentation of the incident and corrective actions is also required.

What information must appear on load plaques?

Section 4.5 requires that permanent load plaques (at least 50 square inches each) be posted in visible locations. Plaques must clearly show:

• Maximum unit load per level (or average unit load).
• Maximum uniformly distributed load per level.
• Total average and maximum loads per bay.
• Number and spacing of storage levels as per the original design. Plaques must be updated if any configuration changes occur, and the information must match the LARC drawings.

What are LARC drawings, and when are they required?

Load Application and Rack Configuration (LARC) drawings document every permissible storage configuration, including limits on the number of levels, spacing, and height. They are required for any rack designed with multiple configurations and must be updated if modifications, repairs, or reconfigurations are made. LARC drawings are essential for safe operation, compliance, and ongoing maintenance.

What are the allowable out-of-plumb and out-of-straight limits?

Section 4.10 specifies:

• Out-of-plumb: Maximum deviation is 1/240 of the upright height (≈ 1/2 inch per 10 feet).
• Out-of-straight: Maximum deviation is also 1/240 of the upright height (≈ 1/2 inch per 10 feet). If these limits are exceeded, the affected columns must be unloaded, re-plumbed, and repaired or replaced before returning to service.

What seismic design provisions apply to pallet racks?

When required by local building codes, racks must be designed, manufactured, and installed to resist earthquake loads and lateral forces. This includes site-specific seismic hazard analysis, anchorage, and drift limitations, all documented in the rack design.

What are the requirements for beam locking devices?

Beams in machine-loaded racks must include locking devices or bolts at each connection, capable of resisting an upward force of 1,000 lbf (4,450 N) without failure or disengagement. These devices prevent beams from lifting or detaching during forklift operations and must be inspected regularly for presence and condition.

What standard governs welded-wire rack decking?

Where decking supports the load, it must comply with ANSI MH26.2, which defines the design and testing requirements for welded-wire deck performance. Rack decking must be rated for uniformly distributed loads and not used for point loads or hand stacking unless specifically designed for such applications.

hat are the requirements for shims beneath rack baseplates?

Shims may be used to level racks, but must:

• Be made of material equal to or stronger than the floor’s bearing strength.
• Match or exceed the base plate’s footprint.
• Have a total thickness less than six times the diameter of the largest anchor bolt.
• If the shim stack exceeds two times the anchor bolt diameter, locking shims or additional measures may be required to ensure stability.

If you’re unsure whether your baseplates or shims meet ANSI MH16.1 requirements, it’s best to consult a qualified Damotech expert to verify compliance and long-term safety.

What is the maximum height-to-depth ratio allowed for racks?

For racks with straight-column frames, the height-to-depth ratio must not exceed 6:1. If it exceeds 6:1, additional stability measures, such as special anchoring, bracing, or engineering analysis, are required to prevent tipping.

What if a rack exceeds the 6:1 height-to-depth ratio?

Racks taller than 6:1 and loaded by powered equipment must be specially engineered to resist a 350 lbf (1,560 N) side force at the top level. Single rows exceeding 8:1 should be tied externally or cross-aisled for stability unless a qualified engineer certifies that anchoring alone is sufficient. Enhanced anchoring, bracing, or overhead ties may be required.

What does ANSI MH16.1-2023 say about posting design loads for elevated structures?

All design loads for rack-supported platforms, pick modules, and walkways must be clearly posted in a conspicuous, permanent location within the structure, typically at stairway or ladder access points. The signage must indicate the maximum live load, dead load, and any other relevant load limitations, and must be maintained and updated if modifications occur.

How can Damotech help ensure compliance with ANSI MH16.1-2023?

Damotech’s engineering and inspection teams help warehouse operators comply with RMI’s ANSI MH16.1-2023 by:

• Evaluating rack damage and structural integrity.
• Certifying repairs to restore the original load capacity.
• Updating or providing LARC drawings and load plaques.
• Designing compliant anchoring, shimming, and rack repair solutions.

Contact our experts to schedule a rack inspection or engineering assessment and ensure your warehouse meets the latest safety standards.