General Information on Stainless Steel Wedge Anchors
Stainless steel wedge anchors are designed for use in moist, wet environments. When the application is indoors or in a dry environment, use the standard zinc plated carbon steel wedge anchors. "Wedge anchor" is the generic name for a specific type of anchor used to fasten an item to solid concrete. A stainless steel wedge anchor is manufactured from two different types of stainless steel.
Grade 303/304, commonly called 18/8 stainless steel wedge anchors, are excellent for use in a wide range of atmospheric environments. This type of stainless steel with its chromium-nickel and low carbon provides ease of manufacturing and cleaning. It is commonly used in wet environments or when it will be submerged in water that is free of chemicals. The 316 stainless steel has superior corrosion resistance when exposed to many types of chemicals corrodents, such as sea water, brine or chlorine, as compared to the 303/304 and other chromium-nickel steels.
The 316 stainless steel wedge anchor costs more than the 303/304 stainless steel wedge anchors because the steel itself cost more and it takes more time and machining to manufacture,
Many manufacturers do not make all diameters of wedge anchor in stainless steel. Most companies do not carry the 5/16”, 7/8” and 1-1/4’ in stainless steel. Concrete Fastening Systems has available all diameters for both 303/304 and 316 stainless steel and nine diameters to choose from 1/4”, 5/16”, 3/8”, 1/2”, 5/8”, 3/4”, 7/8”, 1” and 1-1/4. The diameter of wedge anchor chosen for any specific job is determined by the weight of the object being fastened, the diameter of the holes in the item being attached, or is specified by an engineer.
Each diameter of stainless steel wedge anchor must be embedded into the concrete a minimum distance for holding power. This minimum depth of embedment will ensure minimum holding values. Deeper embedment beyond minimum embedment may increase holding values but may also create problems. A problem that may occur at deeper embedment is running into rebar embedded in the concrete. Another problem at embedment of 8” to 12” is difficulty drilling the hole straight enough for the anchor to be fully inserted.
The chart below shows the minimum embedment depth for only those wedge anchors sold by Concrete Fastening Systems™, Inc.
Minimum Embedment for Stainless Steel Wedge Anchors
|Anchor Diameter||Minimum Embedment|
Length of Anchor
Each diameter of stainless steel wedge anchor is available in a number of different lengths. Most manufacturers do not make all lengths for both types of stainless steel. Concrete Fastening Systems has all lengths for both types as well as the ability to manufacture special lengths if needed. The minimum length of anchor required for any specific job is determined by adding the thickness of the material being fastened to the minimum embedment plus space for the nut and washer. The length of a stainless steel wedge anchor is measured as an overall length from one end to the other.
The length of threads on the stainless steel wedge anchors can vary based on the diameter and length of the anchor being used. The amount of threads should be sufficient to allow for the nut and washer to be threaded once the anchor is installed in the concrete. To install the stainless steel wedge anchor properly, 3 to 4 threads must be below the surface of the concrete or item being attached in order to provide a draw on to ensure proper expansion.
Each diameter and length of stainless steel wedge anchor is packaged with the correct number and size of nut and washer. The quantity in each box differs based on the diameter and length as well as the manufacturer.
- Stainless steel wedge anchors do not require the bottom of the hole to set the anchor properly. The hole depth can extend past the embedment depth of the anchor and can be any depth as long as it allows the anchor to be installed at or past minimum embedment. Each manufacturer has different installation instructions. Recommendations by Concrete Fastening Systems for the installation of their wedge anchor are below, as well as links for the installation instructions for other manufacturers:
- Drill a hole in concrete using a carbide bit and a hammer drill. The diameter of the carbide bit is the same diameter as the stainless steel wedge anchor being used. Make sure the carbide bit meets ANSI Standards B212.15 to ensure proper hole size for the wedge anchor. The hole needs to be drilled a depth that is a minimum of one anchor diameter deeper or 1/2” deeper than the wedge anchor will penetrate in order to allow space for debris to fall during the installation process. The fixture can be used for a template but check that the holes in the fixture are large enough for the drill bit to fit through.
- Before inserting the stainless steel wedge anchor, clean debris from the hole using a wire brush, vacuum or compressed air. This step ensures that the hole is clean of any debris and is critical for successful anchor installation.
- Put the washer on the stainless steel wedge anchor and thread the nut on. Make sure that the nut is threaded so that the top of it is level with the top of the wedge anchor, which will help protect the threads from any damage while hammering the anchor into the hole.
- Insert the stainless steel wedge anchor with the clip end first through the fixture or directly into the hole in the concrete. Using a hammer, hit the wedge anchor and nut with sharp blows until the washer and nut are snug against the base material or fixture. It is critical that there is a minimum of 6 threads below the surface of the concrete or the fixture because these threads will be required to set the wedge anchor.
- Tighten the nut to finger tight and then take a wrench and turn the nut 3 to 5 times to the recommended installation torque. This pulls the wedge anchor up, wedging the clip between the steel stud and the wall of the hole in the concrete.
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