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Product Information
| Close Mesh Bar Grating is formed by a pressure locked process where the cross bars and rectangular bearing bars are forced together using tremendous hydraulic pressure. The result is a flush top, durable grating that provides excellent lateral support and a small open space between the bearing bars. Swaged gratings with narrow openings are also available. |
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| Close Mesh Series |
McNICHOLS’® Close Mesh products are divided into five series: GCM-1, GCM-2, GCM-3, GCM-4, GCM-5. Each series has specific bearing and cross bar spacing, bearing bar sizes, weights, load characteristics, fastener requirements, etc. Links to Close Mesh series information are provided below:
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| Material Selection - |
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| Center to Center Bearing Bar Spacing |
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| Center to center bearing bar spacing is the of distance from the center of one bearing bar to the center of the next bearing bar. See the spacing table for more information on GCM Series center to center bearing bar spacing. |
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| Center to Center Cross Bar Spacing |
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| Center to center cross bar spacing is the distance from the center of one cross bar to the the center of next cross bar. See the spacing table for details on the GCM Series cross bar spacing. |
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| Construction |
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Close Mesh Bar Grating is formed by a pressure locked process where the cross bars and rectangular bearing bars are forced together using tremendous hydraulic pressure. The result is a flush top, durable grating that provides excellent lateral support.
The bearing bars run parallel to the length or span of a standard grating panel and are responsible for the product’s load bearing capabilities. The cross bars, which run parallel to the width of the span, are primarily responsible for holding the bearing bars together. However, they also play a factor in deflection characteristics, especially for concentrated loads which are not distributed across the span of the grating. |
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| Surface |
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Welded bar grating is available with the following surfaces:
· Smooth - Standard surface.
· Serrated - Serrations are cut into the grating’s bearing bars surface
· Grip TightTM - Grit is bonded to the grating surface.
Grip TightTM surfaces provide slip resistance and are available by special order. |
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| Banding |
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Bar grating panels, pieces, or trench grating can be banded to provide strength and to provide a finished look. Banding is the welding of a rectangular metal bar to the ends of the bearing bars. Two banding types are available, based on the placement of the welds.
· Load Banding - The metal bar is welded at every bearing bar. Load banding is commonly used in trench grating applications where high loading requirements exist (i.e. motorized wheel traffic). Note: Aluminum products are not load banded.
· Trim Banding - The metal bar is welded only at every 4th to 6th bearing bar. Trim banding is commonly used for pedestrian traffic applications where loading is not a factor. |
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| Bearing Bar Height |
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| The bearing bar height, also known as bearing bar depth, is measured from the bottom of the bearing bar to the top. See the appropriate GCM Series load table for the available bearing bar heights. |
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| Bearing Bar Thickness |
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| The bearing bar thickness, also known as bearing bar width, is the distance between the left surface of the bearing bar and the right surface of the same bearing bar. The standard rectangular bearing bar thickness for Close Mesh grating is 3/16 inch. A smaller bearing bar thickness is available in 1/8 inch. |
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| Span |
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| The span of the grating is the length of the grating between grating supports. In order to perform in accordance with its design loading characteristics, grating must be installed so that the bearing bars are parallel to the span. This is necessary because bearing bars are the primary elements which support the load applied to the grating. |
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| Clear Span |
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| Clear span is the length of unsupported grating. Grating supports typically have a foot or ledge on which the grating rests. The part of the grating resting on the support is not part of the clear span. For example, if a 36-inch long piece of grating rests on two supports, each with a 3-inch ledge, the clear span would be 36 inches minus the part of the grating resting on the ledge (which is a total of 6 inches). In this example, the clear span would be 30 inches. |
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| Loading Information |
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When selecting a specific bar grating, it is important to know how much the grating will deflect (i.e. bend) under load. Deflection is determined by consulting a load table. Click for more information on load tables.
Types of load
Grating applications are subject to two common load types: Uniform and Concentrated.
Uniform Load
Uniform load is applied equally to the full width and span of the grating . It is measured in pounds per square foot.
Concentrated Load
Concentrated load is applied to the full width of the grating at mid-span and is not equally distributed across full length of the span. Concentrated load is measured in pounds per foot.
Grating in some applications may be subjected to a concentrated load over only a portion of its width. This is called a partial load. The deflection in a partial load is determined by the stiffness of both the bearing bars and the cross bars, and varies with the type of grating used. To determine carrying capacity of gratings subject to partial loads, click on live help, email us at internet.sales@mcnichols.com or call McNICHOLS (1-800-237-3820). |
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| Traffic Type |
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If you don’t know the bearing bar height and thickness you require, the appropriate grating size can be determined from the load the grating is expected to carry. The following information is required.
What type of traffic will the grating support?
If only people are supported, specify pedestrian.
Note: Close Mesh grating is not suitable for barefoot pedestrian or wheel traffic. |
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| Width |
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| The maximum panel width is 2 feet. The width of cut-to-size pieces are a function of bearing bar spacing—see the length/width tables for exact cut-to-size widths. |
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| Length or Span |
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| The standard panel length is 8 feet. Panels may also be cut-to-size.The bearing bars run the length of the panel and this is also the direction of the grating span that provides optimum loading capacity. Please consult the appropriate load table for application requirements. |
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| Load Tables |
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| Quantity |
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| Quantity is the number of bar grating pieces you will need. McNICHOLS will quote you on the exact quantity you specify and inform you if minimum quantities apply. |
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| Cut Type and Stubs |
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Bar Grating can be cut three ways to produce three different types of stubs: random, uniform, or equal stub. The cutting costs vary according to the material, number of cuts, and type of cut.
Random cut
This is the most cost effective cut and is standard. When two equally-sized, randomly-cut pieces are placed side-by-side, the cross bars may not line up. The measurements for equal pieces will be the same; however, the distance from the bearing bar ends (stubs) to the cross bars will vary from piece to piece and end to end.
Uniform cut
When two equally-sized, uniformly-cut pieces are placed side-by-side, the cross bars will line up, but may not be centered. The measurements for equal pieces are the same; however, the distance from the bearing bar ends (stubs) to the cross bars will not be the same on both ends but will be uniform from piece to piece.
Equal Stubs
When two equally-sized pieces with equal cut stubs are placed side-by-side, the cross bars will line up and will be centered. The measurements for equal pieces are the same and the distance from the bearing bar ends (stubs) to the cross bars will also be the same on both ends. |
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| Clips and Fasteners |
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| Anchor Blocks are typically used to secure Close Mesh bar grating. If you want anchor blocks, McNICHOLS will quote the specific size appropriate for your grating. You can also secure grating with a counter sink. This can be accomplished in the field, but will require special equipment. Where easy removal is not critical, Close Mesh can be secured by welding. |
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| Open Space |
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Open space is the clear spacing between the bearing bars. It is also the difference between the center to center bearing bar spacing and the bearing bar thickness. For example, open space for GCM-1 with a bearing bar thickness of 3/16 inch is 1/4 inch (7/16 inch bearing bar centers - 3/16 inch bearing bar thickness = 1/4 inch openspace). The chart to the right lists the Close Mesh bar grating open space.
| Close Mesh Open Space |
| Series |
BB Thickness |
Open Space |
| GCM-1 |
3/16 inch
1/8 inch |
5/16 inch
1/4 inch |
| GCM-2 |
3/16 inch
1/8 inch |
3/8 inch
5/16 inch |
| GCM-3 |
3/16 inch
1/8 inch |
1/2 inch
7/16 inch |
| GCM-4 |
3/16 inch
1/8 inch |
9/16 inch
1/2 inch |
| GCM-5 |
3/16 inch
1/8 inch |
11/16 inch
5/8 inch |
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| Open Area |
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Open area is the total area of the space between the cross and bearing bars divided by the total area of the bar grating panel and is expressed as a percent. The larger the open area, the higher the percentage of light, air, or fluid that can pass through the grating.
| Close Mesh Open Area |
| Series |
BB Thickness |
% Open Area |
| GCM-1 |
3/16 inch
1/8 inch |
54.5%
68.8% |
| GCM-2 |
3/16 inch
1/8 inch |
59.6%
72.0% |
| GCM-3 |
3/16 inch
1/8 inch |
67.4
77.5% |
| GCM-4 |
3/16 inch
1/8 inch |
69.9%
79.0% |
| GCM-5 |
3/16 inch
1/8 inch |
73.9%
81.5% |
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| Tolerances |
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There are standard tolerances for shearing (cutting) heavy weld grating products. If you do not specify a tolerance, the standard tolerance applies. Tolerances can be specified on the quote form.
More information on tolerances. |
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ADA Information
 McNICHOLS offers a wide selection of ADA products which meet the ADA Requirements for Spacing when installed in compliance with guidelines. |
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