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TOWER BOLTS

Hot Dip Galvanizing per ASTM A153 CLASS B & C / F2329.
Mechanical Galvanizing per ASTM B695 CLASS 55.
Zinc Plating and Plain Finish.

A394 Tower Bolts come in the following types/grades:

  • Type 0 – Hot-dip zinc coated bolts made of low or medium carbon steel
  • Type 1 – Hot-dip zinc coated bolts made of medium carbon steel, quenched and tempered
The ASTM A153 Specification
ClassDescriptionMin. Avg. Coating Thickness, mils
B-13/16″ and over in thickness and over 15″ in length3.4
B-2Under 3/16″ in thickness and over 15″ in length2.6
B-3Any thickness and under 15″ in length2.2
CFasteners over 3/8″ in diameter and similar articles, washers 3/16″ to 1/4″ thick2.1
The ASTM B695 Specification
ClassMinimum Thickness, μm
5553
Class 55 is the most common class used for ASTM fasteners and is roughly the same thickness as hot dip galvanizing per ASTM F2329. 53μm is equivalent to 0.002087 inches or 2.087 mils.
F2329 Coating Thickness
Dimension
Minimum Thickness on Surface
Average Thickness of all Specimens (Production lot)Average Thickness of all Specimens (Batch lot)Average Thickness of Individual Specimen
Fasteners over 3/8” in diameter0.0020 in.0.0017 in.0.0017 in.
Washers 3/16″ to 1/4″ thick0.0020 in.0.0017 in.0.0017 in.
Fasteners 3/8” and under in diameter0.0017 in.0.0015 in.0.0015 in.
Washers under 3/16″ thick0.0017 in.0.0015 in.0.0015 in.