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Pallet storage racks were created to optimize warehouse and distribution center operations. As individual storage rack manufacturers developed new and competing products, the need for design and utilization standards and their implementation by the user and producer industries became obvious.

The Rack Manufacturers Institute (RMI) was established and incorporated in 1958 to deal with industry-wide issues. Among its initial activities was development of the first edition of an RMI standard, Minimum Engineering Standards for Industrial Steel Storage Racks, which was issued in 1964. It represented the first step in developing specifications and other products designed to suit the needs of users, manufacturers, and the engineering and code-enforcement communities.

From Fema-460 – September 2005

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RMI’s New Video Overviews The Basics Of Rack Maintenance And Repair

RMI has produced and released a new video offering some basic guidelines for inspecting, maintaining and repairing industrial steel storage rack systems to ensure a safe working environment. The video is targeted to both potential and current end users and owners of storage rack and runs less than four minutes.

Among the key points in the video are making sure that the rack system is maintained in its original configuration—including using the pallets that the system has been designed to support and the fork trucks it has been sized for—will minimize the risk of damage.

Additionally, if it is deemed necessary to reconfigure the current rack structure, the best practice is to return to the original engineer of record, or to engage a different professional rack design engineer prior to doing so. This ensures that the system’s load capacity can be maintained.

Should damage occur—typically due to a collision with a fork truck or an incorrect installation—the rack’s load carrying capacity is likely to be reduced. This puts the system at an increased risk of collapse. Instead, a decision must be made to repair or replace the damaged components; the video explores how to choose between the options.

Further, the video notes that a qualified rack engineer should be involved in the repair process to ensure that the obvious damage is repaired properly and to determine if the rest of the structure’s integrity has been affected. Other key points include a review of baseplate and anchor bolt spacing, ultimate capacity of the system after repair or replacement, and how documentation should be updated to reflect any changes.

This video is the third in a planned series of industrial steel storage rack safety videos. The first episode covered storage rack system selection; the second shared insights into installation and safety inspections.

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Why Are Pallets Important For Pushback System Safety?

Last-in/first-out (LIFO) pushback racking systems (like the vast majority of industrial steel storage rack systems) are designed for use with specific pallet types, loads and rack configurations. For that reason, it is critically important to ensure that operators only load the pushback system with pallets approved for use within it. Not doing so can negatively impact the system’s safety, structural integrity and smooth operation because it increases the risk of a pallet not being seated securely on the cart within its lane.

Because they are engineered to utilize a combination of friction between the pallets and the pushback carts and rails (as well as physical skid stops and/or beam stops to keep pallets in place), care should be taken to maintain the integrity of each lane. Ice, lubricants or liquid on the pushback rails or carts can potentially reduce the friction between the pallet and the pushback system, allowing the pallets to slide forward. To prevent this, inspect the rails and carts periodically and clean as needed.

Further, because pushback rack systems often rely on the pallet loads themselves to push each load and its cart backwards into the lane as new ones are added, both pallet and load integrity are essential. Damaged pallets or those with broken, split or cracked bottom boards—or exposed fasteners—can cause load hang-ups within a lane. Likewise, so can loads that have not been properly unitized or stretch wrapped to ensure that the contents are secure. A pallet load with overhanging slip sheets, carton flaps, loose stretch wrap, improperly stacked cartons, or boxes that have been jarred out of position can easily snag within the system, causing a jam.

Finally, never mix load weights within a single lane of pushback rack, as it increases the potential for a heavier pallet to push a lighter one out of alignment or out of the system. That’s because different pallet weights generate different degrees of friction within the system, increasing the risk of failure, damaged product or injury.

Find out more about how to safely use pushback rack systems, here.

The post Why Are Pallets Important For Pushback System Safety? appeared first on RMI Safety.

Recommended Safety Practices For Case Picking Of Products Stored In Pushback Rack Systems

Because they support high-throughput order fulfillment of single product—typically fast movers—some operations utilize pushback racking storage systems as part of their picking process. In order to ensure that pickers are able to perform their assigned tasks safely when working with a pushback system, there are a few recommended best practices. These guidelines include:

1. Always follow the recommended procedures published by the push back system’s manufacturer. Picking from systems deeper than two pallets is normally discouraged because the back pressure created by more than a single pallet may become difficult for an operator to control when removing empty pallets.

2. Picking from a pushback system should only occur at floor level to ensure operator safety. Likewise, the system should be positioned low enough for the operator to safely reach all cases without stepping on a partially empty pallet.

3. Pushback systems utilized for picking should have beam-mounted pallet stops installed at every pick face to ensure that a partially loaded pallet is securely held in place and not pushed forward by the loaded pallet behind it, potentially injuring the operator.

4. When a pallet is completely empty, the safest practice is for a forklift to remove it, rather than the operator manually lifting it by hand. This is because the forklift can far more easily control the speed at which the pallet is removed—and therefore the speed at which the subsequent pallet descends down the lane—than an operator. Additionally, removing an empty pallet by hand can place a high degree of ergonomic strain on the operator, who must bend down and lift it. Further, if there are any obstructions (such as a lift truck) behind the operator attempting to manually remove the empty pallet, the back pressure of the subsequent pallet might cause him or her to be pinned.

5. If an empty pallet must be removed manually (and the loads are not too great), the safest procedure is for the operator to first confirm that the aisle behind him or her is clear. Then, utilize proper lifting techniques to lift the front of the pallet above the pallet stop and slowly walk backward while dragging the pallet on the pushback rail. This allows the operator to use the empty pallet to maintain control of the speed of the descending load behind it.

To learn more about best practices in safe operation of pushback racks, click here

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RMI Debuts New Rack And Decking Infographic At ProMat 2019

Released at ProMat 2019, RMI’s newest infographic offers an overview of the different available types of industrial storage racking and decking. It also details the benefits of each type of equipment, and the breadth of resources available from the Rack Manufacturers Institute (RMI).

Racking, notes the graphic, delivers operations high storage density, high selectivity, high throughput, efficient picking and unloading, and immediate access to products—among other benefits. Decking benefits include pallet containment, small product storage, support for placement of irregular loads, and more.

The document also notes that pallet racks are among the most widely used type of storage solution in industries such as shipping and manufacturing. Further, it shares that the last decade has seen a total of expansion of available warehouse space by 1-billion square feet, bringing total U.S. warehousing space to 9.1-billion square feet.

RMI members represent the industry’s leading suppliers of industrial steel storage racks and related structural systems. They supply industrial rack solutions worldwide and in virtually every major manufacturing and distribution center. The organization was formed in 1958 and offers a variety of resources via its website at www.MHI.org/RMI.

Want your own copy of the RMI Rack Infographic? It’s available as a free download, here.

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The Safest Way To Unjam A Pushback Rack System

Even though the wheeled carts in industrial pushback racking storage systems are designed to travel smoothly backward and forward from the point of pallet insertion and removal, jams can sometimes occur. Common causes of hang-ups include improper loading of pallets, broken pallet boards, or overhanging items in the load (slip sheets, carton flaps, loose stretch wrap, improperly stacked cartons, or boxes that have been jarred out of position). To safely un-stick a pallet in a pushback lane, there are several approaches—and none of them involve an operator climbing in front of a live, loaded pushback system, which has a high potential of injury.

First, there are several preventive measures that minimize the risk of hang-ups, such as:

  • Only use the types of pallets for which the system has been designed.
  • Do not place pallets whose loads have not been stretch wrapped or unitized into the pushback system.
  • Carefully inspect each load prior to placement in the pushback lane to ensure proper unitization and no product, slip sheet or stretch wrap overhang.
  • Do not place damaged pallets or those with broken, split or cracked bottom boards, or exposed fasteners into the system.
  • Always control the speed of the load with the forklift when inserting and removing a pallet. This prevents pallets from advancing too fast and potentially colliding with each other or the front of the system. Such impacts can prompt boxes to come loose and fall, creating a jam.
  • Do not mix load weights within a single lane, as it increases the potential for a heavier pallet to push a lighter one out of alignment or out of the system.
  • Do not side-shift a pallet resting on a pushback cart; doing so will likely knock the cart out of alignment and off the rail.
  • Periodically inspect the system’s carts and rails to ensure all components are intact and that any debris or other material is removed.

If, after following all the aforementioned best practices in preventing hang-ups, a jam still occurs, these are the recommended steps for clearing the lane.

  1. Operators should never climb into a live pushback lane to attempt to clear a stuck pallet, as the risk of a serious injury is high. Instead, all pallets from an adjacent pushback lane should be removed first.
  2. A forklift should be positioned to hold the jammed lane in position. The adjacent—now empty—lane must be secured with tie-offs, after which an operator can enter it on a man-lift to ascertain the cause of the hang-up.
  3. From the adjacent empty lane, the stuck load can be freed from the side. If it is not possible to easily clear the obstruction, unload the pallet from the side to remove the weight of the load before releasing the blockage and removing the pallet.
  4. Once the hang-up has been resolved, unload the jammed lane with a forklift. Then, inspect the lane’s pushback rails and cart wheels for damage and/or debris. Clean as necessary prior to reloading. (More tips on the safe use of pushback rack systems can be found here.)

Looking for more storage rack safety guidelines? RMI will be presenting a free educational seminar, “Storage Rack Safety 101,” on Wednesday, April 10 at ProMat 2019 in Theater F at 11:15 a.m.

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Best Practices In Safe Operation Of Pushback Rack

Industrial pushback racking storage systems are engineered to store pallet loads on both sides of an aisle at higher cubic densities approximately 25% to 65% greater than selective racking. That’s because these systems are built with a series of nested carts that roll atop inclined steel rails, typically two to six pallets deep per storage lane. Individual pallets are placed on each cart in succession, with the new pallet pushing back the load placed before it. Because the lanes are loaded front to back, they provide last-in/first-out (LIFO) access, making pushback racking systems ideal for storing multiple pallets of the same product, particularly fast movers.

Because pushback rack systems rely on the pallet loads themselves to impel each load and cart in the series through the lane as they are stored—and upon gravity for the loads and carts to descend during removal (as opposed to a mechanized device)—pallet placement must be relatively precise. A lane of pallets also generates a significant amount of force, particularly on the load at the pick face. Therefore, it’s important to ensure operators are well versed in the best practices for safe loading and unloading a lane of pushback rack.

Safe Loading (also called “Insertion”) Practices: First, it’s important to only load a pushback system with the pallet style or type it was designed for; not doing so can negatively affect system performance and increase the risk of a pallet not being seated securely in the lane. Additionally, loads must be placed on undamaged pallets and shrink wrapped or otherwise securely unitized to prevent products or cases from toppling off during loading or unloading.

To begin the safe and proper placement of the first pallet into a pushback lane, the fork truck must be positioned squarely to the opening. The operator should lift the load approximately 3-4 inches above the top cart, centering the pallet over the cart (or over an optional centered stop device positioned on the lane’s front beam). With slope cart systems best practice is to tilt the forks up slightly to match the pitch of the rail. Once in the properly aligned position, the pallet is inserted into the system until it is properly placed. At that point, the pallet load should be slowly lowered onto the cart to prevent an abrupt impact that may cause the bottom boards to break.

After lowering—but before removing the forks—the operator should confirm that the pallet is aligned properly as instructed by the manufacturer. The forks can then be removed slowly, maintaining the proper angle of alignment to prevent damage to the pallet or the racking.

To insert additional pallets, the next load is raised to a height approximately 4 inches above the cart. This ensures that the next pallet makes contact with the pallet already loaded in the system ahead of it and allowing the new pallet to push against the loaded pallet (instead of the load), preventing product damage and hang-ups. Then the previously described process repeats, with the new pallet placed as instructed by the manufacturer prior to slowly lowering it and removing the forks. The final pallet placed in the lane will rest on the pushback system’s rails and behind (not on top of) the optional beam pallet stop device if used.

If any resistance is encountered when inserting pallet loads, the loading process should be stopped, and the issue investigated before proceeding. Common causes of hang-ups include improper pallet centering or positioning, prompting the pallet to snag on another cart or hit the uprights alongside the lane.

Safe Unloading Practices: For safe and proper removal of a pallet from a pushback lane, the forklift should first be aligned square to the rack face with the forks tilted up slightly to match the upward slope of the system prior to entering the fork openings. Once the pallet is on the forks, it should be lifted about 4 inches prior to backing out of the system.

Critically, the speed of the forklift as it backs out with the load is what controls the descent speed of the subsequent pallets and carts. Therefore, load removal must be both controlled and no faster than the speed of the subsequent pallets as they flow forward in the lane. If a forklift exits with its load too quickly, the following loads may advance too fast, colliding with the front of the system and causing damage to the racking. The impact may also jar the load, prompting boxes to come loose and fall—raising the risk of both injuries and product damage.

Tips on safe approaches to un-jam pushback rack systems can be found here.

Looking for more storage rack safety guidelines? RMI will be presenting a free educational seminar, “Storage Rack Safety 101,” on Wednesday, April 10 at ProMat 2019 in Theater F at 11:15 a.m.

The post Best Practices In Safe Operation Of Pushback Rack appeared first on RMI Safety.

Safe Approaches To Unjamming Pallet Flow Systems

Although its designed for the pallets stored within it to flow smoothly from the point of loading (also called “charging”) to the pick face, sometimes a jam occurs in pallet flow rack (also known as “gravity flow”). Whether it’s a pallet that’s settled onto the tracks, debris in the gravity wheels or roller lanes, temperature and humidity changes that have affected the wood pallet, or a broken stringer, hang-ups happen. There are a variety of approaches to safely un-stick a pallet in the lane—and none of them involve an operator climbing into a live, loaded flow system, which has a high potential of injury and is never recommended.

The first technique to try is known as “plugging” the pallet flow. In this process, a forklift positioned squarely at the discharge/pick face end of the lane lifts the front pallet 1-inch above the rollers. Once lifted, the forklift uses the pallet to firmly push (or bump) the pallet load behind it by 3-4 inches. As the forklift backs out with the first load onboard, the subsequent loads should follow.

If plugging does not work, the removed pallet should be replaced in the pick face position and the entire system should be inspected to identify the type and location of the blockage.

The next step is to try to dislodge a stuck pallet from the loading end of the lane by placing another loaded pallet into the system. The force generated by the new pallet as it glides down the lane should dislodge the stuck one. If not, continue to load the lane until the pallet releases or the lane is full.

If after loading the lane behind the stuck pallet does not resolve the hang-up, remove the last pallet loaded. Then, remove all the pallets in the lane adjacent to the one with the jam. After securing the empty, adjacent lane with tie-offs and any other facility-mandated safety procedures, an operator may enter it to inspect and diagnose the reason for the hang-up. If it is possible to correct the issue manually—and safely—the operator should do so.

However, if it’s not possible for the jam not be cleared manually, the last technique is to load pallets from the discharge/pick face end until the new pallets reach the stuck pallet. This permits the hung-up pallet to be pushed back toward the loading end. The operator in the secured adjacent lane can also report to the lift truck driver about the progress of new loads upon contact with the stuck pallet.

To learn more about best practices in safe operation of pallet flow racks, click here

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Why Pallet Flow Systems Are Designed For Specific Pallets And Loads

The vast majority of industrial steel storage rack systems—including pallet flow (or “gravity flow”) rack—are engineered specifically for a single storage purpose. Likewise, when designing a high-density pallet flow system, there are a number of variables that must be taken into account to ensure its safety, structural integrity and smooth operation. Two of the most critical variables are the load itself and the type of pallet it rests on.

Assessing The Load

In order to design a rack system with adequate capacity to handle a given load, the design engineer must be informed of the weights and dimensions of the individual loads intended for the system.

The weight of the load impacts the type of pallet flow used (full roller, split roller, skate wheel and more), its pitch and the beams used. Further, the depth, width and height of the load (or of the largest load if there are multiple types) must also be known. That’s because the overall capacity of the rack frame is determined by the vertical distance between shelf beams (which brace the structure), the weight of the loads placed on the beams, and the weight of the flow lane tracks.

When calculating beam spacing, typically an additional 12 inches are added to the height of the load—6 inches for pallet height and 6 inches of clearance space to allow a forklift to place or remove the load from the point of entry or exit. Because the beams act as upright supports, the tighter the beam spacing, the denser the design and the stronger the rack bay. If different types of loads are to be stored within the same system, the entire structure must be designed to accommodate the heaviest load to ensure safe operation and minimize the risk of collapse.

Assessing the Pallet

As the point of contact between load and the rollers or skate wheels, the pallet is also a critical element of pallet flow system design. Type, dimension and orientation of the pallets to be used in a system can have a significant impact on its design.

  • Type means the material used in the pallet’s construction (wood, plastic, metal or resin). Each material has its own unique set of properties that could impact the ease with which the pallets flow down a lane. This will guide the decision about the type of flow tracks used (roller or wheel) to facilitate smooth operation.
  • Dimension is the length and width of the pallet, which determines the number that can fit within a given lane, and the number of lanes a building can accommodate.
  • Orientation refers to the construction and configuration of the pallet’s underside. For the smoothest operation and the lowest risk of a hang up within the system, it is optimal to place pallets in a lane with the bottom boards running parallel to the direction of the flow. However, because pallets can be used in both directions, it might be more space efficient to design the system with the bottom boards running perpendicular to the flow. Additionally, the quality, number and thickness of the bottom boards—as well as the shape and orientation of the undersides or feet of certain plastic or metal pallets—must be considered, as they too can impact pallet flow performance.

Looking for more information on how to pick the optimal pallet rack system for your operation? RMI will be presenting “Warehouse Racking Systems for the E-Commerce World,” at ProMat 2019 on Wednesday, April 10 at 2:15 p.m. in Theater B in the South Hall of McCormick Place.

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Applying Pallet Separators, Speed Controllers To Flow Rack

Because high-density pallet flow (also called “gravity flow”) rack is engineered to hold multiple pallet loads in a lane with a downward pitch, they are increasingly popular for use in case-picking operations. Full pallets are loaded from the back, or charging, end atop a series of rollers or skate wheels; the forces of gravity draw the pallets forward to the pick-face, or discharging, end. This allows pickers to split case pick from full pallets.

However, because the pallets in the lane rest against each other, they generate a substantial amount of force on the pallet at the pick-face. This effect, known as pallet flow back pressure, is approximately 6% of the full weight of all rear pallets.

3-deep system, 2,500 lb. load. Back pressure = .06 x 2,500 lbs. x 2 pallets = 300 lbs.

That increased force can make it extremely difficult for a picker to lift and remove the front pallet when empty. Attempting to do so has the potential for ergonomic injuries due to repetitive bending, stretching and straining.

To mitigate pallet flow back pressure, a pallet separator (sometimes referred to as a “hold-back” or “braking” device), can be added to the lanes. This interlocking component pops up above the roller or skate wheel tracks to stop and hold the series of pallets behind the one at the pick-face, typically at a distance of 6 to 12 inches. That negates the forces prohibiting the front pallet from being easily removed. To advance the pallet flow, a manual release latch is triggered by the operator, allowing the next pallet to index into pick-face position.

When used in deep-lane flow, the device relieves the pressure otherwise experienced by the lift truck. That increases forklift driver productivity while preventing product damage as it eliminates the forces that prevent easy removal of the empty pallet.

For further control of pallet movement as each indexes forward in a lane, two other accessories can be added:

  • Speed Controllers: Braking devices mounted below the roller tracks or dropped in on top of wheeled tracks—typically at a single pallet interval—that ensure pallets advance at a controlled, steady pace. In addition to minimizing the risk of product or pallet damage, the controllers help to keep the loads centered in the lane, reducing the risk of a hang-up.
  • Ramp Stops: Also referred to as “end stops,” these devices are bolted onto the discharge end of the pallet flow rack lane and slow the advance of the first pallet, stopping it safely and holding it securely at the pick-face.

Looking for more storage rack safety guidelines? RMI will be presenting a free educational seminar, “Storage Rack Safety 101,” on Wednesday, April 10 at ProMat 2019 in Theater F at 11:15 a.m.

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Best Practices In Safe Operation Of Pallet Flow Rack

Pallet flow rack (also sometimes called “gravity flow”) is a high-density, dynamic storage system engineered to hold up to 20 pallets in a single lane. Loaded back to front for first-in/first-out load access, the pallets ride atop gravity wheel or roller lanes mounted at a slight pitch that slopes downward from the loading point to the pick face. These systems are ideal for storing multiple pallets of the same product, particularly fast movers.

Because it relies on gravity to move the loads through the lane—as opposed to a mechanized device—pallet flow rack requires fairly precise pallet placement. A lane of pallets also generates a significant amount of force, particularly on the load at the pick face. Therefore, it’s important to ensure operators are well versed in the best practices for safe operation of pallet flow rack at three key points: loading, unloading and clearing a hang-up within a lane.

Safe Loading (also called “Charging”) Practices: For safe and proper pallet placement, the fork truck must be positioned squarely to the opening side of the lane, with the center pallet stringer aligned with the center flow lane. (To further ensure correct pallet positioning, optional entry guides can be added to the outside of the flow rails at the point of entry, helping to straighten an off-center pallet.)

The load should be raised 2-3 inches above the lane rollers. Once in position, the forks are tilted forward, allowing the pallet to first make contact with the rollers or wheels, then roll away from the vehicle and down the lane until it meets the preceding pallet load. When placing the load, it’s important to avoid contact between the fork tips and the lane wheels, and to not place pallets with broken or missing bottom boards into the system, as either instance could cause a jam within the lane. After placement is complete, the forklift should back away from the opening completely prior to turning to avoid an impact with the uprights.

Safe Unloading Practices: For safe and proper pallet removal from the discharge/pick face end of a lane, the forklift should first be aligned square to the rack face prior to entering the pallet’s fork openings. Once the pallet is on the forks, it should be lifted to a level position high enough to clear the front beam, yet still low enough to make contact with the loaded pallet behind it. Before extracting the pallet, the forklift operator should gently push it back against the subsequent pallet load to help start forward flow of the rest of the lane; after slowly removing the pallet, the remaining loads will advance to the aisle face. (If they don’t advance, refer to the “Safe Jam Clearing Practices” section below.)

Safe Jam Clearing Practices: First, operators should never climb into a live flow system to attempt to clear a stuck pallet, as the risk of a serious injury is high. Instead, a technique known as “plugging” is recommended. To begin, a forklift positioned squarely at the discharge/pick face end of the lane lifts the front pallet 1-inch above the rollers. Once lifted, the forklift uses the pallet to firmly push (or bump) the pallet load behind it by 3-4 inches. As the forklift backs out with the first load onboard, the subsequent loads should follow.

If this does not work, the removed pallet should be replaced in the pick face position and the entire system should be inspected to identify and address the blockage.

Looking for more storage rack safety guidelines? RMI will be presenting a free educational seminar, “Storage Rack Safety 101,” on Wednesday, April 10 at ProMat 2019 in Theater F at 11:15 a.m.

The post Best Practices In Safe Operation Of Pallet Flow Rack appeared first on RMI Safety.