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Stainless Steel Large Diameter Tapcon

Tuesday, April 30, 2013
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Available Diameters

Two diameters are available in the 410 stainless steel: the 3/8” and 1/2”. The 5/8” and 3/4” are manufactured only using the zinc plated grade 5 material.

Head Type

One head style is available, which is referred to as a hex serrated washer head. The serration on the underside of the hex washer head is designed to prevent anchor back-out. Dimensions of the head are as follows:

Diameter of AnchorHex Head DiameterWasher Diameter
3/8” 9/16” 13/16”
1/2” 3/4” 1”
5/8” 13/16” 1-3/16”
3/4” 13/16” 1-3/16”

Length Indication

Each head is stamped with a letter designating the length of the anchor. This identification is required to allow for inspection that can verify the embedment depth of the anchor.  The letter code identifies the length of the anchor is greater than the first number and less than the second number.

A 1-1/2” < 2”
B 2” < 2-1/2”
C 2-1/2” < 3”
D 3” < 3-1/2”
E 3-1/2” < 4”
F 4” < 4-1/2”
G 4-1/2” < 5”
H 5” < 2-1/2”
I 5-1/2” < 6”
J 6” < 6-1/2”

Hole Diameter in Fixture

The predrilled hole in the fixture must be larger than the diameter of the designated diameter of the anchor being installed. This will ensure that the anchor will pass through the hole and into the base material. Below is a table showing the hole diameter in the fixture and the anchor diameter:

3/8” 1/2”
1/2” 5/8”
5/8” 3/4”
3/4” 7/8”

Minimum Embedment

Each diameter of anchor must be installed into the base material a minimum distance for the anchor to obtain minimum holding values. Depending on the quality and strength of the base material that the anchor is being installed, deeper embedment may increase holding values.

S. S. LDT DiameterMinimum Embedment
3/8” 1-1/2”
1/2” 2-1/2”
5/8” 2-3/4”
3/4” 3-1/4”

Depth of Hole

The hole must be drilled to a depth which will ensure that the anchor does not bottom out in the hole and will allow space for any dust that is created during the installation process to fall into and out of the way. It is recommended the depth of the hole should no less than the following:

S. S. LDT DiameterDepth of Hole
3/8” 2-1/2”
1/2” 3-1/2”
5/8” 3-3/4”
3/4” 4-1/4”

Diameter of Masonry Bit

The bit used to install the anchors should have a carbide tip, meet ANSI standard B212.15-1994 and be used in a hammer drill that is set in the hammer and rotation mode. The diameter of the bit is smaller than the designated diameter of the anchor.

Diameter of AnchorBit Diameter
3/8” 5/16”
1/2” 7/16”
5/8” 1/2”
3/4” 5/8”

Installation Steps

Concrete – Light Weight Concrete

  1. Drill a hole in the concrete using the proper diameter carbide bit for the diameter of the anchor being installed. Drill the hole a minimum of 1” deeper than the anchor embedment.
  2. Insert anchor into the hole and tighten until fully seated, using an impact wrench or using a socket wrench by hand. Be sure not to over torque.

Hollow or Grout-Filled CMU ( for 3/8” or1/2”)

  1. Drill a hole in the base material a minimum of 1” deeper than the embedment depth of the anchor using the correct diameter carbide tipped bit for the diameter of LDT being installed.
  2. Insert the anchor into the hole and then tighten the anchor by hand with a socket wrench until fully seated. Make sure that anchor is not over torqued.

You can purchase LDT Tapcons from us here.

LDT DiameterBit Diameter
3/8” 5/16”
1/2” 7/16”
5/8” 1/2”
3/4” 5/8”

Hole Perpetration

After the correct diameter hole has been drilled in the concrete it must be cleaned of all dust and debris. This can be done using a vacuum, wire brush or compressed air.

Hole Depth

The hole needs to be drilled a minimum of 1/4” deeper than the large diameter will penetrate the concrete. This extra space at the bottom of the hole ensures that the LDT will not bottom out in the hole and allows space for the dust created during the tapping process to fall into and out of the way.

Minimum Embedment

Diameter of AnchorMinimum Embedment Depth
3/8” 1-1/2”
1/2” 2”
5/8” 2-3/4”
3/4” 3-1/4”

Installations Instructions for LDTs

WARNING – Failure to follow these instructions can result in serious personal injury. For any concerns or questions regarding proper installation, application or appropriate use of the large diameter tapcon, call the technical department of the manufacturer, ITW/Redhead, at 1-800-899-7890. Always wear safety glasses that meet ANSI standards. Using the wrong diameter drill bit will affect the holding values and may cause failure.

  1. Select the proper diameter, head style, and length of large diameter Tapcon screw.
  2. Choose proper diameter drill bit for the diameter of the anchor being installed.
  3. Drill hole ¼” deeper than the tapcon anchor is embedded in the base material.
  4. Drill hole. To ensure proper drill bit length and depth of the hole, refer to the selection chart.
  5. Drive anchor.

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Always use personal protective equipmentAs 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 Fastening Systems, 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.

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