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| Long Way of Trench |
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| The long way of the trench is the measure of the trench’s length and is at a ninety degree angle (nonparallel) to the direction of traffic. |
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| Short Way/Span of Trench |
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| The short way or span of the trench is the measure of the trench’s width. The direction of traffic runs the same direction (parallel) as the span of the grating. Since the load is carried by the bearing bars, they must be parallel to the short way of the trench. |
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| Product Type |
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Trench Grating can be made of several bar grating product types listed below. Welded bar grating is the most common and the most cost effective Trench Grating product.
· Welded
· Heavy Weld
· Swaged Rectangular Bar
· Swaged I-Bar
· Swaged Flush Top Bar
· SAFE-T-GRID®
· Close Mesh
· Riveted
· Press Locked
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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. If wheel traffic is to be supported, choose between “on-” or “off-road” vehicles. On-road vehicles include trucks, cars or any other vehicles that could be registered and licensed. If the vehicle would not typically be registered, a construction vehicle or forklift, for example, then specify “off-road.”
For Wheel Traffic Only
If the traffic includes off-road vehicles, then it is necessary to know:
· Weight or capacity of the vehicle in pounds
· Wheel diameter in inches
· Width of wheel in inches
· The tire type, either solid or pneumatic (air filled)
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| Angle Iron Depth |
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The angle iron depth is the height of the angle iron that supports the Trench Grating. This is typically the same as the bearing bar height since this results in a grating that is flush with the trench surface. If the angle iron depth is already determined, then a bearing bar height that is equal to the depth must be chosen. Standard bearing bar heights are: 3/4, 1, 1–1/4, 1–1/2, 1–3/4, 2, 2–1/4, or 2–1/2 inches. Other heights for deeper angle irons and heavier loads are available by special order.
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| Material Selection |
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· Plain Steel
· Painted Black
· Galvanized
· Aluminum
· Stainless
Other materials are available by special order. See the material description page.
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| Surface |
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Trench grating is available with either a smooth surface or a serrated surface. The smooth surface is the most common surface that provides great slip resistance. The serrated surface provides even greater slip-resistance where snow, oil, grease, or other slippery conditions exist. A Mebac surface is also available.
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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).
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 Thickness |
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The bearing bar thickness, also known as bearing bar width, is the measurement of distance between the left surface of the bearing bar to the right surface of the same bearing bar. The standard rectangular bearing bar thickness for Trench Grating is 3/16 inch. Smaller bearing bar thicknesses of (1/8, 1/4, 5/16, 3/8, or 1/2 inch ) are also available.
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| Bearing Bar Spacing |
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Bearing bar spacing is the of distance from the center of one bearing bar to the center of the next bearing bar. The standard bearing bar spacing for Trench Grating is 1–3/16 inch. Other bearing bar spacings are available.
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| Cross Bar Spacing |
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The cross bar spacing is the measurement of distance between the center of one cross bar to the center of next cross bar. The standard spacing of the cross bars is 4 inch on center. Cross bars on 2 inch centers are also available.
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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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| Trench Grating Environment |
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Please specify the environment or area that the Trench Grating will be in use. Different environments require different material types; therefore, it is important to specify the environment (i.e. salt water, petrochemicals, caustics, etc.).
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