ASME B18.2.1 Heavy Hex Bolt

Features, Weight Calculation & Technical Drawing

A typical drawing for the heavy hex bolt manufactured in accordance with ASME B18.2.1

Heavy hex bolt manufactured in accordance with ASME B18.2.1 has a larger hex head than that of a standard hex bolt. The body diameter and head height of a heavy hex bolt are the same as that of a standard hex bolt. Two dimensional differences distinguish a heavy hex bolt from a standard hex bolt of the same nominal size are associated with the width of the head: the width across flats, F of the former is 1/8″ lager than the latter; the width across corners, G of the former is 0.144″ larger than the later. The weight of a heavy hex bolt can be calculated using the following equation: Weight_heavy = ρ × [3 × 31/2 ÷ 8 × G2 + πE2L/4], ρ is the density of bolt material.

Full-Size Body Diameter, E & Head Hight, H

Width Across Flats, F & Width Across Corners, G

Radius of Fillet, R & Nominal Thread Length, L_T

For L ≤ 6″, L_T equals twice the basic thread diameter plus 0.25″; For L > 6″, L_T equals twice the basic thread diameter plus 0.50″. For bolts that are threaded full length, L_G defines the unthreaded length under the head, and L_G ≤ 2.5 × P for sizes ≤ 1″ while L_G ≤ 3.5 × P for sizes > 1″ (P = thread pitch). If bolt size ≤ 1″ and L ≤ L_T + 2.5 × P, or, if bolt size > 1″ and L ≤ L_T + 3.5 × P, the bolt shall be threaded for full length.