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ESA Expansion Screw Anchor


The ESA was the original internally threaded mechanical anchor design. The malleable lead shield allows for secure mounting.


Cone: Die-cast Zamac 3 alloy; expander shield: 3–5% antimonial lead


  1. Drill a hole in the base material using the appropriate-diameter carbide drill bit as specified in the table. Drill the hole to the specified embedment depth plus 1/8" for flush mounting. Blow the hole clean using compressed air. Overhead installations need not be blown clean.
  2. Insert anchor into hole.
  3. Using a piloted setting punch, drive expander shield over cone.
  4. Position fixture, insert fastener and tighten.


  • Meets Federal Specifications A-A-1922A, Type 1, except ESA50.

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Product Information Tables

ESA Product Data and Allowable Tension Loads in Normal-Weight Concrete
Internal Thread Size (dia. - threads per in.) Model No. Drill Bit Dia. (in.) Embed. Depth (in.) Allowable Tension Load (lb.) Quantity
f'c ≥ 3,000 psi Box Carton
1/4 - 20 ESA25 1/2 7/8 190 100 500
3/8 - 16 ESA37 3/4 1 1/4 380 50 200
1/2 - 13 ESA50 7/8 1 1/2 400 50 200