User:Mgkay/Industrial shelving

Industrial shelving is a steel storage system designed to accept and store unpalletized loads, placed thereon, either manually, semi-automatically, or automatically such as by an automated storage and retrieval mechanism. In its basic open form, it is comprised of upright columns, the desired number of formed steel panels which constitute horizontal shelves, and end and back braces. Steel back and side panels may be substituted for bracing to form enclosed shelving units.

In addition to the basic component parts, a wide variety of accessories, such as vertical or horizontal dividers, label holders, doors, bin fronts, base fronts, modular drawers and shelf boxes may be added to increase the utility of the unit. Units may be assembled with nuts and bolts, clips and/or studs. Shelves may be attached to upright columns punched on multiple-hole centers for vertical adjustment. Shelves are available in a number of strength classes and sizes determined by the load requirement of the application. Columns may be spliced one to the other to form high-rise shelving. Steel shelving may also be tiered to form two or more shelving levels employing a decking system and stairway.

Steel shelving

Steel shelving is generally grouped into two basic classifications. Standard Industrial shelving, utilizing horizontal shelves up to 48” wide between upright columns and Boltless or Wide Span nshelving utilizing horizontal shelves in excess of 48” wide. Wide Span shelving, although frequently but not necessarily employing component parts similar to design and function to those parts used in conventional Pallet Storage Racks, is classified as shelving because application is exclusively for the storage of non-palletized material.

Industrial steel shelving

Industrial steel shelving is generally referred to as a steel structure comprised primarily of vertical posts (columns) and metal shelves, that are clipped or bolted to the vertical posts. The stability of the structure relies on vertical cross bracing or metal panels, bolted to the sides and rear of the structure. The forces are being transferred to the bracing through the shelves which acts as a diaphragm.

Industrial boltess shelving

Industrial Boltess Shelving is structure that does not rely on clips or bolts and is comprised primarily of vertical posts (columns) and horizontal shelf beams, in both down aisle and cross aisle direction. The shelf itself is supported on the perimeter by horizontal beams and is typically made out of wood, MDF, metal, wire or any type of surface for the product to be deposited on. The stability of the structure relies on the connection between the shelf beams and the vertical posts.

Post and shelf types

Posts

Posts are a vertical upright member that supports the horizontal shelf. Columns are manufactured in a variety of configurations.

Shelves

Shelves are formed steel which attaches horizontally to the post columns and supports the load. Shelves are available in many sizes and a number of capacities. They should be specified based on the customer’s requirements and uniformly distributed load capacity that the shelf must support. Steel gauge, shelf formation and reinforcing varies from manufacturer to manufacturer and thus determines shelf capacity.

Design considerations

Codes

Before beginning to apply a product, attention must be given to assuring compliance to all codes and restrictions. These would include but not be limited to federal, state, local, fire, building (IBC - International Building Code) and safety and health codes (OSHA- Occupational Safety and Health Administration). Your local municipal engineer and/or shelving supplier can offer assistance in determining which codes may apply for your installation.

Layout

Consideration should be given to the layout of the desired shelving storage area. Effort should be expended to find the best arrange-ment considering such things as width, depth of shelf selected, clearance for handling the stored item (loading and unloading) and adequate working aisle width to service the shelf.

Shelf selection

Consideration should be given to the load expected to be carried on a single shelf including size and height of the load. Under certain conditions, multiple stacking of product on one shelf may be in order. (Caution: Multiple stacking increases the spacing between shelves and may reduce column capacity – see Upright Column Loading Section). Once the load area and amount of load (in pounds or psf) is determined, reference to a manufacturer’s load chart will aid in the selection of the proper shelf. Shelves are rated using an Evenly Distributed Load (EDL). Shelves come in various classes for differ-ent magnitude and type of loads. In selection of the shelf its deflection must be considered as some shelves under safe loading might cause functionally or aesthetically unacceptable deflection. A class of shelf to overcome this can be selected.

Upright column loading

Once the proper shelf has been selected, it now becomes necessary to make a selection of the proper column. Two of the more critical factors to consider when selecting a column are the:

1. Maximum distance between shelves (as space between shelves increases, capacity of column decreases).
2. Total weight applied to the entire unit.

It must be noted that removal or rearrangement of one or more shelves will affect column capacity.

Bracing for stability

Shelving requires the use of side and back bracing to prevent sway and lateral movement. This bracing is most commonly accomplished by using bars, straps, or angles placed in an “X” arrangement, or by using rectangular plates, gussets, or corner braces. In using the braces, it is important that they be located in the proper position ver-tically. Closed backs (panels) and closed sides (panels) provide the same bracing function as those noted above. Have your shelving manufacturer provide you with the proper bracing pattern for your application.

Connections

There are many ways to connect shelves to the column. The pre-dominant methods are mechanical fastening (nut and bolt), compression clips, or ledge type clips. Care must be exercised to assure overall integrity of the shelving unit regardless of the type of connection used.

Plumbness

Shelving should never be installed without assurance of plumbness and levelness in all directions. An out-of-plumb installation will cause an eccentric loading condition and can result in a need to derate or reduce the rated capacity of the unit. If you have checked the unit and find it is out-of-plumb and/or out-of-level, you can correct the problem by using foot plates and/or shims, or adjusting the bracing. It is a good idea to anchor and even to tack-weld the shims to the foot. Have your shelving manufacturer provide shims, foot plates, and installation details.

Anchoring

Anchoring the shelving unit should provide resistance to overturning, keep the unit from shifting, and create a more rigid structure. A common anchor is a steel footplate attached to the vertical column and, subsequently, secured to the floor with a variety of floor anchors (the footplate also better transfers the load and protects the floor surface). A less common way of anchoring the unit is to tie directly to the building. While this can be quite acceptable, it should NEVER be done without a review by a qualified engineer to assure that no adverse loading is transferred between the building and the shelving.

Collision protection

If shelving is to be installed in an area that may be adjacent to or integrated with material handling vehicles, provision should be made to prevent accidental impact and subsequent damage to the columns and other members. This may be accomplished by installation of corner protectors fastened or imbedded in the floor or guide or guard rail or other barriers in appropriate areas.

Floor protection

Consideration must be given to the type of floor (concrete, wood, asphalt, steel, etc.) upon which the shelving installation is being placed. Overall loading (usually given in pounds per square foot) can be calculated and compared with the rated capacity of the floor system and its supporting structure. This is especially important if the installation is on an upper level floor. Concentrated loads (usually given in pounds per square inch) under the shelving columns can cause local failure or deterioration of the floor surface. Foot plates or load distribution plates may be necessary to avoid this condition.

Concentrated loads

Shelf loading can vary anywhere from an evenly distributed load (EDL) to a concentrated load. All theoretical capacity calculations (load and deflection) are based on an assumed EDL; however, in actual practice a true EDL is almost unachievable. A non-EDL causes the shelf to act as though it were more heavily loaded. Shelf loads and deflections given by a manufacturer are usually based on EDL. The factor of safety used in these figures will usually allow for modest non-EDL; however, if a radical departure from EDL is expected, and then provision must be made in the customer’s specification for this condition. Where non-EDL is expected your shelving manufacturer can assist in providing the proper structural characteristics. Shelves should never be used as a "ladder" to reach higher shelves.

Impact loading

The rated capacity of industrial shelving is stated as an evenly distributed load (EDL). Even the smallest amount of impact during loading/unloading (especially mid-span at the leading edge) can create an adverse loading situation and result in damage to or failure of the product. If an impact load is anticipated, your Shelving manufacturer can offer a number of practical solutions. A common solution is the addition of reinforcing bars or angles installed in the front, rear, or side flanges as appropriate.

Overturning

A very important consideration when laying out and applying the shelving is to prevent the unit from toppling or overturning. Overturning of a shelving unit results from a number of conditions that can cause instability.

1. Overloading the top portion of the shelving
2. Non-uniform loading
3. Out-of-plumb installation
4. Impact

Among the more common ways to prevent this from happening is to securely anchor the unit and/or tie the units together across the aisle at the top. Your shelving supplier will guide you as to how to best deal with overturning.

Maintenance

Shelving should be periodically inspected for:

1. Loose bolts
2. Damaged columns or shelves
3. Proper seating of shelf and clip
4. System not overloaded

Any damage is dangerous. Column damage is most serious; units should be unloading immediately and repaired or replaced before to service.

See also

• Material handling
• Material handling equipment
• Shelf

External links

• American National Standards Institute (ANSI)
• Material Handling Industry
• Storage and Manufacturers Equipment Association (SMA)