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 insures 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 place 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 be
used to set the anchor in the base material. Each diameter of ESA
requires a different setting tool. To insure 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 #
|
Size
|
Bit Diameter
|
Min. Embedment
|
Box Quantity
|
|
ESA10
|
#10 - 24
|
3/8”
|
5/8”
|
100
|
|
ESA25
|
1/4” – 20
|
1/2”
|
7/8”
|
100
|
|
ESA37
|
3/8” – 16
|
3/4”
|
1-1/4”
|
50
|
|
ESA50
|
1/2” - 13
|
7/8”
|
1-1/2”
|
50
|
ESA Setting Tool Requirements
|
Setting Tool Part #
|
ESA Part #
|
|
PSP10
|
ESA10
|
|
PSP25
|
ESA25
|
|
PSP37
|
ESA37
|
|
PSP50
|
ESA50
|
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 fixture over the ESA, then insert bolt through
the fixture and into the ESA, turning clockwise until tight.
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.