Wedge anchors are used for many different concrete applications, such as the following:
|Fence Post||Sign||Light Post|
|Water Pipe||Fire Sprinklers||Exit Sign|
|Railing||Roof Flashing||TV Antenna|
|Duct Work||Conduit||Car Lift|
|Man Door||Overhead Door||Escalator|
|Desk||Park Bench||Bike Rack|
How thick is the item that is being fastened by the wedge anchor?
This is an important consideration because the length of the wedge anchor is in part determined by this factor. To determine the length of wedge anchor to use for any particular application, add the thickness of the material being fastened to the minimum embedment for the diameter of wedge anchor being used plus space for the nut and washer. The final number will equal the minimum length wedge anchor to use for any application.
What diameter of wedge anchor is being used?
The diameter of the wedge anchor is determined in a number of different ways. The general rule is that the heavier the object being fastened then the larger the diameter of wedge anchor that must be used. The diameter of the hole in the item being fastened will provide information regarding the largest diameter that can be used; i.e. the 5/8” hole in the fixture will require a wedge anchor diameter less than 5/8”. An engineer may specify both the diameter and the embedment depth of a wedge anchor to be used. When an engineer specifies a specific wedge anchor, then that exact wedge anchor should be used.
Wedge anchors for specific diameters have a minimum embedment depth that the anchor must be installed in order for the wedge anchor to obtain minimum holding values. The minimum embedment is the depth at which the wedge anchor must be installed into the concrete after it has been expanded. This minimum embedment is different for each diameter of wedge anchor and is critical to the performance of the wedge anchor. The wedge anchor can be installed at deeper depths of embedment with deeper embedment depths usually creating higher holding values. Embedding wedge anchor at deep embedments of 8”, 10”, or 12” should not be attempted because problems will arise. One such problem would be whether or not the hole would be straight enough to insert a wedge anchor without the wedge anchor hitting the sidewalls of the hole in the concrete. The longer length wedge anchors are designed for different thickness of the material being fastened but not necessarily for deeper embedments.
Below is a chart showing the minimum embedment for each diameter of wedge anchor:
|Diameter of Wedge Anchor||Minimum Embedment Depth|
Each wedge anchor requires that a hole is drilled into the concrete for the wedge anchor to be inserted. The diameter of the hole is equal to the diameter of the wedge anchor that is being installed, i.e. a 3/8” wedge anchor requires a 3/8” hole. When drilling into concrete, a hammer drill must be used and be set in the hammer and rotation mode. Along with the hammer drill, a carbide tipped bit must be used and this bit must meet ANSI standards. ANSI standard carbide tipped bit ensures that the hole size tolerance will equal the hole tolerance requirements of the wedge anchor being installed.
The depth of the hole is very important and must be drilled to a depth that meets the requirements for the wedge anchor being installed. The depth of the hole must be 1/2” deeper than the wedge anchor will be inserted, ensuring that the hole is deep enough to meet minimum embedment requirements. This extra 1/2” space is critical because debris may be created during the installation process and it must have space to fall out of the way to make sure that the wedge anchor is installed properly.
Wedge anchors are manufactured from different materials for use in different applications. The standard zinc plated carbon steel wedge anchors are used for indoor applications where moisture is not present. The hot-dipped galvanized wedge anchors are used in outdoor applications where moisture may be present; the 303/304 stainless steel wedge anchors are for wet environments where the anchor may be submerged in water. The 316 stainless steel wedge anchors are used in submerged liquid applications such as salt water or chlorine.