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Structural Bolting
structural-bolting
Heavy Hex Structural Bolts
(9)- Top of Head. Top of head shall be full form and chamfered or rounded with the diameter of chamfer circle or start of rounding being equal to the maximum width across flats within a tolerance of minus 15%.
- Head Taper. Maximum width across flats shall not be exceeded. No transverse section through the head between 25% and 75% of actual head height, as measured from the bearing surface, shall be less than the minimum width across flats.
- Bearing Surface. Bearing surface shall be flat and washer faced. Diameter of washer face shall be equal to the maximum width across flats within a tolerance of minus 10%. Thickness of the washer face shall be not less than 0.015 in. nor greater than 0.025 in. for bolt sizes 3/4 in. and smaller; and not less than 0.015 in. nor greater than 0.035 in. for sizes larger than 3/4 in.
The plane of the bearing surface shall be perpendicular to the axis of the body within the FIM limits specified for total runout. Measurement of FIM shall extend as close to the periphery of the bearing surface as possible while the bolt is being held in a collet or other gripping device at a distance of one bolt diameter from the underside of the head. - True Position of Head. The axis of the head shall be located at true position with respect to the axis of the body (determined over a distance under the head equal to one diameter) within a tolerance zone having a diameter equivalent to 6% of the maximum width across flats at maximum material condition.
- Body Diameter. Any swell or fin under the head or any die seam on the body shall not exceed the basic bolt diameter.
Heavy Hex Nuts for Use with Structural Bolts
(9)- 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.
Hardened Steel Circular and Circular Clipped Washers
(9)- Dimensional Conformance. Circular and circular clipped washers shall have the following characteristics inspected to ASME B18.18.2, to the inspection levels shown :
Inside diameter - Inspection Level B
Visual - Inspection Level C
If verifiable in-process inspection is used. - Nominal washer sizes are intended for use with comparable nominal diameters.
Quality Assurance
Unless otherwise specified, products shall be furnished in accordance with ASME B18.18.1 and ASME B18.18.2.
Hardened Beveled Washers with Slope or Taper in Thickness 1:6
(9) Notes:- Dimensional Conformance. Beveled washers shall have the following characteristics inspected to ASME B18.18.2, to the inspection levels shown :
Inside diameter - Inspection Level B
Visual - Inspection Level C
If verifiable in-process inspection is used. - Non-clipped washers may be rectangular providing neither side dimension is less than L, and one side may be longer than that of the L min included in the table.
- Nominal washer sizes are intended for use with comparable nominal bolt diameters.
- Clipped edge E shall not be closer than 0.875 times the nominal bolt diameter from the center of the washer.
Compressible Washer - Type Direct Tension Indicators
(18)- Dimensional Conformance. Direct tension indicators shall have the following characteristics inspected to ASME B18.18.2, page M-11, to the inspection levels shown:
Characteristic
Inside Diameter - B (Inspection Level)
Protrusion tangential diameter - B (Inspection Level)
Visual - C (Inspection Level)
If verifiable in-process inspection is used - Nominal direct tension indicator sizes are intended for use with fasteners of the same nominal diameter.
