The Hilti Drop-In, referred to as an HDI, is an anchor manufactured and sold by Hilti, Inc. The Hilti drop-in anchor
is a female anchor which in an internally threaded, flush mounted
expansion anchor designed for use in solid concrete only. The standard
HDI is made from carbon steel and then zinc plated. It is also available
in 303 stainless steel. The HDI is manufactured with standard national
coarse threads in five diameters- 1/4", 3/8", 1/2", 5/8" and 3/4"
Other versions of the HDI for specific applications are
available. The HDI-P is a short version of the HDI which is available in
the 3/8" diameter only. The HDI-P is designed for use in hollow-precast
and post tensioned concrete. The HDI-S, which is only available in the
1/2" diameter, has internal coil threads and is used in concrete forming
applications where coil rod is used. The HDI-L has a lip on the
threaded end that allows for consistent anchor embedment and rod
Each diameter is available in one length and all need to be set
with a setting tool that is purchased seperately. The setting tool most
commonly is the hand setting tool. The 3/8" and 1/2" diameters have an
automatic setting tool that fits into a hammer drill so that the drill
can be used to set the anchor.
HDI is mainly used in applications for hanging pipe, trapeze and
electrical conduit from concrete ceilings. The hole to be drilled in the
concrete must be larger than the designated diameter of the HDI since
the designated diameter refers to the inside diameter of the HDI.
HDI anchors can be installed in four simple steps. It is
important that a hammer drill be used for drilling the hole in the
concrete base material. The hammer drill is used in conjunction with the
properly sized carbide bit that will make the best hole, which is
essential since hole and anchor sizes are critical.
How to Install a Hilti HDI Drop-in Anchor
1. Adjust the depth gauge or put tape on the drill bit to
measure the HDI drop-on anchor so that once the hole is drilled, the
anchor will be flush with the surface of the concrete.
2. Using a hammer drill in the hammer & drill mode, drill the
hole in the concrete making sure the hole depth is equal to the length
of the HDI being used.
3. Use a wire brush, compressed air or vacuum to clean the hole of all debris.
4. Drop the HDI drop-in anchor into the hole that you drilled in
the concrete in Step #2. Using the correct setting tool for the diameter
of anchor being used, drive the setting tool with a hammer until the
shoulder of the setting tool meets the shoulder of the HDI drop-in
anchor. Now the HDI anchor will be correctly set.
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:
Bob Carlisle, President of Concrete Fasteners
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.