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Simpson Expansion Screw Anchors

Published by Robert Carlisle on Jul 31st 2008

Purchase Single Expansion Anchors

Expansion screw anchors (ESA) or more commonly called machine screw anchors are the internally threaded fasteners designed for use in concrete, brick or block. ESA stands for expansion screw anchor and is sold by Simpson Strong-Tie Anchor Systems®, a part of Simpson Strong-Tie. The ESA expansion screw anchor is a two-piece anchor the internally threaded cone is made from a die cast Zamac 3 alloy and the expander shield is made for a 3% to 5% antimonial lead material.

ESA Federal Specifications

The ESA expansion screw anchor meets federal specifications A-A-1922A, Type 1, except the ESA50, which is the 1/2” expansion screw anchor.

Size Availability

ESA expansion screw anchors are available in four (4) different diameters from Simpson Strong-Tie Anchors a #10, 1/4”, 3/8” and 1/2”. Concrete Fastening Systems, Inc. offers three (3) additional sizes 5/16”, 5/8” and 3/4”.

ESA Minimum Embedment

For the ESA expansion shield to acquire holding values in the base material it needs to be inserted to a minimum depth. The minimum depth of embedment is different for each diameter of ESA expansion shield. The #10 ESA requires a minimum depth of embedment of 5/8”, 1/4” requires 7/8”, 3/8” requires 3/4” and the 1/2” requires 7/8”.

ESA Thread Size

ESA expansion shield anchors are designated by the inside diameter or the diameter of the bolt or threaded rod that can be screwed into it. All of the threads for the ESA expansion shield are national coarse threads, which refer to the number of threads per inch. The thread requirements for each diameter are #10-24, 1/4”-20, 3/8”-16, 1/2”-13.

Hole Diameter for expansion screw anchors

The diameter of the hole that needs to be drilled for the ESA expansion shield anchors is the same diameter as the outside diameter of the anchor. The hole should be drilled using a carbide tipped bit that meets ANSI standards. The #10 ESA expansion screw anchor needs a hole 3/8” in diameter, 1/4” needs a 1/2” hole, 3/8” needs a 3/4” hole and the 1/2” needs a 7/8” hole.

Hole Depth for ESA

The depth of the hole drilled into the base material must be at a minimum of the length of the anchor; this ensures that minimum depth of embedment requirements are met. The hole can be drilled deeper to allow the anchor to be inserted into the base material for better holding values. In most cases, the deeper the embedment of the anchor the better the holding values will be. The hole should be drilled 1/8” deeper that the anchor length to allow for dust created during the drilling and installation process.

Bolt Length

The length of the bolt needed is equal to the thickness of the material being fastened plus the depth of embedment of the anchor.

ESA Base Material Thickness

The thickness of the base material that the ESA is placed in must be at least 1-1/2” times the depth of the embedment of the ESA. If a 1/4” ESA anchor is embedded into the base material 1” than the overall thickness of the material should be 1-1/2”.

Setting Tools Needed for Expansion Screw Anchors

The ESA expansion screw shield requires that a setting tool is used to set the anchor in the base material. Each diameter of ESA requires a different setting tool. To ensure that the anchor is properly set, the lip of the setting tool must meet the lip of the anchor. The nubbed end of the setting tool is inserted into the ESA, striking the setting tool with a hammer pushes the expander shield over the cone, expanding it against the interior wall of the base material.

ESA Product Information

Part #


Bit Diameter

Min. Embedment

Box Quantity


#10 - 24





1/4” – 20





3/8” – 16





1/2” - 13




ESA Setting Tool Requirements

Setting Tool Part #

ESA Part #









Expansion Screw Anchor (ESA) Installation

1. With a hammer drill and a carbide bit that meets ANSI standards drill a hole into the base material. Make sure that the hole depth will be 1/8” deeper than the required embedment depth.

2. Using compressed air, vacuum and wire brush clean out the hole of all dust, overhead applications do not have to be cleaned out.

3. Place the ESA expansion shield anchor into the hole in the base material.

4. Insert the correct setting tool for the ESA being used into the anchor and with a hammer strike the setting tool driving the expander over the cone of the anchor.

5. Place hole in the fixture over the ESA, then insert a bolt through the fixture and into the ESA, turning clockwise until tight.

Purchase Single Expansion Anchors