Used in heavy construction, structural bolts made to ASTM (American Society for Testing Materials) specifications are always used with a nut and often with a hardened washer. The bearing surface of structural bolts is flat and washer faced and the point is chamfered.
High quality steel is used for strength and durability on structural bolts, and shall conform to ASTM A325 or A490. (A490 is selected for greater yield and tensile strengths).
Heavy Hex Structural Bolts offer a six-sided head that is considerably thicker and offers more strength across the bearing surface than would a structural bolt with a head of standard thickness.