structural bolts


Structural bolts are specifically designed for use with heavy hex nuts in the connection of structural members (as opposed to tapped holes). The nuts for structural connections shall conform to ASTM A563 or ASTM A194. The washers used for structural connections shall meet ASTM F436 specifications. This specification covers both flat circular and beveled washers.

The structural Bolts following ASTM F3125/F3125M is a structural bolt specification covering inch and metric bolt grades is to use thicker nuts and shorter thread lengths to obtain the required ductility by plastic deformation of the threads within the nut. The structural bolt assembly is used in both preloaded and non-preloaded applications, and it can be argued that in the event of failure by thread plastic deformation the assembly still acts as a non-preloaded assembly. This specification contains 4 inch series bolting grades: A325, F1852, A490, and F2280. These will be addressed in this article. When looking at the mechanical requirements of bolts it appears that a grade A325 and SAE J429 Grade 5 are identical as do the grade A490 and the SAE J429 Grade 8.

Bolt Grades

We offer Structural bolts & nuts in A490, A325 Type 1 & 3, 8, F1325 grade the choice of the grade depends upon the application and requirement of the customer. The grades have separate mechanical characteristics which are defined in the below standard. Although there are some specialist grades designed for specific applications.

  • A325
  • A490
  • ASTM F3125
  • F1852


  • ASME B18.2.2
  • ASME B18.2.1
  • ASME B18.2.6M
  • ASME B18.2.6

Bolts characteristics

  • Less surface pressures
  • High Holding capacity of heavy loads
  • Defined friction properties


HDG, Zinc Plated, Zinc Flake, Black Oxide, Xylan, PTFE, Geomat, Chrome finish

We can offer surface finishing as per customer requirement in hot dip galvanizing, we take special care to ensure there is no hydrogen embrittlement in A325 grade with our special curing system which ensures that Type 1 & 3 grade bolts are not damaged by hydrogen embrittlement post galvanizing process. We also do zinc electroplated in blue, yellow, or black color as per customer requirements.