ASME B18.2.2-2015 pdf – Nuts for General Applications: MachineScrew Nuts, Hex, Square, Hex Flange,and Coupling Nuts(lnch Series).
1.1.1 This Standard is intended to cover the complete general and dimensaonal data for the various types of inch series square and hex nuts, including machine screw nuts and coupling nuts, addressed by this Stan dard. Also Induded are appendices covering gaging of slots in sLotted nuts, wrench openings for nuts, formulas on which dimensional data are based, and measurement of bearing surface runout. It should be undentood that where questions arise concerning acceptance of product. the dimensions in the tables shall govern over recalculation by formula.
1.1.2 The inclusion of dimensional data in this Standard s not intended to imply that all of the products described herein are stock production sues. Consumers are requested to consult with manufacturers concerning lists of stock production sues.
1.2 ComparIson to ISO Standards
There arc no comparable ISO inch fastener standards.
1.3 Dimensions
Unless otherwise indicated, units of measurement are expressed in inches.
1.4 OptIons
Where options are allowed, they shall be selected at the manufacturer’s discretion unless otlwrw kc specifted by the purchaser.
1.5 TermInology References
For definitions of terminology not specific.illv defined in this Standard, refer to ASME BIR.12.
Unless otherwise specified, the standards referenced shall be the latest edition at the time of order placement
ASME Bl.l, Unified Inch Screw Threads (UN and UNK Thread Form)
3.2 Corner FiLl
A rounding or lack of fill at )unction of hex corners with chamfer shall be permissible. provided the width across corners is within specified limits at and beyond a distance equal to 173% of the basic thread diameter from the chamfered face.
3.3 Tops of Nuts and Chamfers
Tops of nuts shall be flat and chamfered. Unless otherwise specified by the purchaser or in this Standard, nuts in sizes 4 in. nominal size and smaller shall be doublechamfered. Larger size nuts shall be double-chamfered or have washer-faced bearing surface and chamfered
3.3.1 Single-Chamfered Nuts and Washer-Faced Nuts. Diameter of the 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 from 5% to 15% of the basic thread diameter. The surface of the chamfer may be slightly convex or rounded.
3.3.2 Double-Chamfered Nuts. Diameter of the chamfer cirde shall be equal to thc maximwn width across flats with a -10% tolerance.
34 Countersink
Unless otherwise specified In this Standard, tapped hales shall be countersunk on the bearing faces. The maximum countersink diameter shall be the thread basic (nominal) major diameter plus 0.030 in. for 4 in. nominal size nuts and smaller, and log times the basic maor diameter for nuts larger than in. No part of the threaded portion shall pro)ect beyond the bearing surface.
35 Nut Thickness
The nut thickness shall be the overall distance, measured parallel to the axis of nut, from the top of the nut to the bearing surface and shall include the thickness of the washer face where provided.
36 Washer Face Diameter
Unless otherwise specified, the outside diameter of washer face shall be equal to the maximum width across flats with a -10% tolerance.
3.7 Slots
When specified in the respective dimensional table, slots shall be normal to nLIt flats, Contour of bottom of sloI shall be at manufacturer’s option. Requirements for gaging slots are specified in Mandatory Appendix 1.
3.8 True Position of Tapped Hole
3.8.1 Hex Nuts. The axis of tapped hole in hex nuts shall be located at true position with respect to the axis of nut body within a tolerance zone having a diameter equivalent to 4% of the maximum width across flats for in. nominal size nuts or smaller and 6% of the maximum width across flats for nuts brgcr than l in., regardless of feature size.
3.8.2 SquareNuts. Thraxisof tapped hole insquare nuts shall be located at true position with respect to the axis of nut body within a tolerance zone having a diameter equivalent to 10% of the maximum width across flats, regardless of feature size.
3.9 BearIng Surface Perpendicularity
&armg surface shall be flat and perpendicular to the axis oF the threaded hole within the specified Full indca• (or measurement (FIM) limit indicated in the tables. See Nonmandatory Appendix C for measurement procedure.
3.10 Threads
3.10.1 Thread Standard. Threads shall meet the requirements of ASME 511.
3.10.2 Thread Class. Unless otherwise specified, threads shall be Unified Standard, Class 2B.
3.10.3 Thread Series. Thread series on nuts may be coarse (UNC), fine (UNF), or 8 thread series (SUN).
3.10.4 Thread Gaging. Unless otherwise specified by the purchaser, gaging lot screw thread dimensional acceptability shall be in accordance with Caging System 21 as specified in ASME B1.3, Screw Thread Gaging Systems for Acceptability.