• Unification. Only the 9/16 size is not unified dimensionally with British and Canadian standards.
  • Tops and Bearing Surfaces of Nuts. Nuts may be double chamfered or have washer faced bearing surface and chamfered top.
    The of chamfer circle on double chamfered nuts and diameter of washer face shall be within the limits of the maximum width across flats and 95% of the minimum width across flats.
    The tops of washer faced nuts shall be flat and the diameter of chamfer circle shall be equal to the maximum width across flats within a tolerance of -15%. The length of chamfer at hex corners shall be 5% to 15% of the basic thread diameter. The surface of chamfer may be slightly convex or rounded.
    Bearing surfaces shall be flat and, unless otherwise specified, shall be perpendicular to the axis of the threaded hole within the total run out (FIM) tabulated for the respective nut size, type, and strength level.
  • Position of Hexagon to Tapped Hole. At maximum material condition, the axis of nut body shall be located at true position with respect to the axis of the tapped hole within a tolerance zone having a diameter equivalent to 4% of the maximum width across flats for 1-1/2" nominal size nuts or smaller.
  • Countersink. Tapped hole shall be countersunk on the bearing face or faces. The maximum countersink diameter shall be 1.08 times the thread basic (nominal) major diameter. No part of the threaded portion shall project beyond the bearing surface.
  • Corner Fill. A rounding or lack of fill at junction of hex corners with chamfer shall be permissible provided the width across corners is within specified limits at and beyond a distance equal to 17.5% of the basic thread diameter from the chamfered faces.
  • Width Across Flats. Maximum width across flats shall not be exceeded.
Unit of Measure

Manufacturer

Manufacturer

N/A Industrial Fasteners Institute

Specifications

Product

N/A Structural Bolting

Unit of Measure

N/A English

Nominal Size or Basic Major Diameter of Thread

N/A 3/4 in

Nominal Size or Basic Major Diameter of Thread (Decimal)

N/A 0.7500 in

Nominal Width Across Flats (F)

N/A 1-1/4 in

Max. Width Across Flats (F)

N/A 1.250 in

Min. Width Across Flats (F)

N/A 1.212 in

Max. Width Across Corners (G)

N/A 1.443 in

Min. Width Across Corners (G)

N/A 1.382 in

Nominal Thickness (H)

N/A 47/64 in

Max. Thickness (H)

N/A 0.758 in

Min. Thickness (H)

N/A 0.710 in

Codes and Standards

Codes and Standards

N/A ASME Draft Revision B18.2.6 2003

Runout of Bearing Face, FIM

Max. Runout of Bearing Face, FIM (Specified Proof Load Up to 150,000 psi)

N/A 0.027 in

Max. Runout of Bearing Face, FIM (Specified Proof Load 150,000 psi and Greater)

N/A 0.020 in
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