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Hilti Drop In Anchors

Published by Robert Carlisle on Feb 2nd 2011

Purchase Drop-In Anchors

Hilti drop in anchors referred to as HDI, are a drop-in anchor designed for use in solid concrete.  Hilti drop-in anchors are a female anchor that require a setting tool to be used to set the HDI in the concrete before inserting a bolt or threaded rod.  HDI stands for Hilti Drop-In. There are five different types of HDI drop-in anchors, each of which are designed for specific applications:

  1. HDI Drop-in Anchor – manufactured from carbon steel and zinc plated, meets a wide range of application requirements, allows shallow embedment and setting below the surface of the concrete.  There are five diameters of HDI: 1/4”, 3/8”, 1/2”, 5/8” and 3/4”, and each diameter of HDI is manufactured in one length.  A setting tool is required to set the HDI into the concrete.
  2. HDI SS 303 Drop-in Anchor – manufactured from 303 stainless steel, meets the same wide variety of applications and allows shallow embedment without sacrificing holding power and can be set below the surface of the concrete.  The use of a setting tool is required for each of the five diameters of HDI concrete anchors.
  3. HDI-P Short Drop-in Anchor – specifically designed for use in hollow core panel, precast and post tension concrete applications where maximum embedment requirements equal 3/4”. The shallow embedment requirement cuts down drilling time for fast installation.  The HDI-P has a lip that allows for flush installation and ensures consistent anchor depth.  The setting tool used with the HDI-P is designed to leave a mark on the lip of the anchor to allow an inspector to determine that the HDI-P has been set properly.
  4. HDI-L Flush Drop-in Anchor – available in three diameters of 1/4”, 3/8” and 1/2” and is manufactured with a lip on the threaded end to provide consistent depth and flush installation.  The hole in the concrete can be any depth longer than the length of the anchor being used.  The HDI-L is perfect for repetitive applications such as suspending threaded rod for a pipe run where distance from the surface, the concrete, and the pipe is critical.
  5. HDI-S Speed Thread Drop-in Anchor – available in only one diameter of 1/2”.  The speed thread drop-in anchors are specifically designed and used with coil rod and cannot be used with any other type of threaded item.  The HDI-S is made from carbon steel that is zinc plated and is not available in stainless steel.

HDI Setting Tools
There are four different types of setting tools that are used for setting the HDI anchors in the concrete:

  • HDI-L/HDI Standard Hand Setting Tool – to be used with a hammer for installing the HDI-L and HDI drop in anchors.  Each diameter of HDI and HDI-L requires a different setting tool.
  • HSD-M Machine Setting Tool – designed for use in a hammer drill for fast accurate setting of large numbers of HDI concrete anchors.  This setting tool is only available for two diameters of HDI: the 3/8” and 1/2”.
  • HSD-G Hand Setting Tool – has a guard to protect the installer’s hand from being struck by the hammer used for striking the setting tool.  The HSD-G is only available for the 3/8” diameter drop-in anchors.
  • HST-P Setting Tool for HDI-P- can only be used for the short 3/8” HDI-P drop-in anchor.

The Hilti drop-in anchor HDI is designed to be used in solid concrete and cannot be used in base materials such as brick or block.   The HDI female drop-in anchors are used primarily for hanging threaded rods for suspended ceilings, ventilations systems, piping systems, heating and air-conditioning and plumbing commercial building applications.

Anchor Designation
The HDI drop-in anchor is designated by the inside diameter of the anchor.  A 3/8” HDI refers to the diameter of threaded rod that can be inserted into it.

Type of Threads
All HDI anchors have national coarse threads, for example, the 1/4” has 20 threads per inch.

Hole Diameter
The diameter of the hole that must be drilled is larger than the designated diameter and matches the outside diameter of the HDI drop-in anchor:


HDI Size

Hole Size











The installation of the HDI and HDI-L drop-in anchors is made up of the following steps.

  1. Adjust depth gauge so that anchor will be flush with the concrete surface when installed.
  2. Drill a hole in the concrete using a hammer drill and the correct diameter ANSI standard carbide tipped bit.
  3. Clean the hole of all dust and debris.
  4. Insert HDI drop-in anchor into hole threaded part facing up.
  5. Insert proper size diameter setting tool into the threaded end, strike setting tool until the lip of the anchor meets the lip of the setting tool.

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