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 conctractors (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 more near 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 show that Concrete Fasteners, Inc. offers the
lowest price found on the internet.
Installation Instructions for the HDI-L
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 guage on the hammer drill will ensure proper drilling
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
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
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.
Article Written By:
Mike Pistorino, Vice-President Operations
Concrete Fasteners, Inc. has over 40 years of experience selling concrete fasteners. We can ship out one box or a whole pallet of concrete anchors. Our products are of the highest quality... "your satisfaction is guaranteed". We ship all orders the same day the order is received.