The Hilti HDI-L drop-in anchor is a drop in anchor that has a lip around the threaded end of the anchor. The HDI-L anchor is manufactured by Hilti, Inc. and comes in five different diameters that refer to the inside, or threaded part, of the anchor. The inside diameters range from 1/4" to 3/4" with outside diameters ranging from 3/8" to 1". These anchors are packaged in boxes ranging in quantity from 100 pieces (in the 1/4" diameter) to 25 pieces (in the larger diameters). The lip on the HDI-L is located on the threaded end so that when it is placed into the concrete base material it can only be set until the lip meets the concrete. This creates consistent embedment and ensures that the anchor is perpendicular to the concrete surface. This can be important when installing threaded rod into the anchor when hanging trapeze, ductwork or other mechanical systems. These are the most popular applications for the drop-in anchor and many contractors (depending on the application) need to use an anchor that allows for consistent embedment for each anchor placed. Other applications which do not require such consistency will require the use of a standard HDI or drop-in anchor.
The HDI-L anchor is made from carbon steel that is zinc plated, which is mainly used in indoor applications. The inside of the anchor has half of its length threaded with national coarse threads and the other half of the anchor is used for the expansion plug and expanding the anchor against the base material. The anchor is slotted on the opposite end of the threads. This is the end of the drop-in anchor that is inserted into the hole first so that the threads are nearer to the surface. The correct setting tool must be used to expand the anchor. The setting tool destination matches the diameter of the HDI-L anchor that is being used. For example, if a 3/8" anchor is being used than a 3/8" setting tool must be used to set the anchor.
The HDI-L should only be used in concrete and never in brick or block base material. Companies such as Concrete Fastening Systems sell a stainless steel version of the drop-in anchor with a lip as well as the zinc-plated version. Typically, companies that sell concrete anchors carry a drop-in anchor using the brand name for this type of anchor. They are equivalent to the HDI-L anchor with respect to the material used for manufacturing and the sizes and the installation methods. A comparison of prices shows that Concrete Fasteners, Inc. offers the lowest price found on the internet.
1. The HDI-L requires a specific depth of embedment. Putting a piece of tape on the drill bit at the desired depth of embedment or setting the depth gauge on the hammer drill will ensure proper drilling depth.
2. Using a hammer drill and the proper carbide drill bit, drill a hole in the concrete to the proper depth.
3. Using compressed air, wire brush, vacuum or blow out bulb, clean out the hole of all dust and debris that was created during the drilling process.
4. Drop the anchor into the hole making sure that the slotted end goes in first and the threaded end is at the surface. Next, tap the anchor lightly until it is flush with the surface of the concrete.
The Hilti HDI-L anchor is an anchor that can only be used in the concrete base material. There are a wide variety of diameters and lengths available that can be used in various applications. Before installation, it is important that the correct size anchor is chosen and the proper depth embedment is reached.
As with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications. This article is meant to serve only as a basic explanation of concrete fasteners. Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.