ASME B18.2.2-2022 pdf – Nuts for General Applications: MachineScrew Nuts; and Hex,Square, Hex Flange,and Coupling Nuts(Inch Series).
LL1 This Standard is intended to cover the complete general and dimensional data for the types of Inch series square and hex nuts, including machine screw nuts and coupling nuts (see Tables 1.1.1-1 through 1.1.1-IS). Also included are appendices covering gaging of slots in slotted nuts, wrench openings for nuts, formulas on which dimensional data arc based, and measurement of bearing surface runout. It should be understood 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 Is not intended to imply that all of the products described herein are stock production sizes. Consumers are requested to consult with manufacturers concerning lists of stock production sizes.
1.2 ComparIson to ISO Standards
There are no comparable 1St) inch fastener standards,
1.3 DimensIons
tinless otherwise indicated, units of measurement are expressed in inches.
lÀ Options
Where options are allowed, they shall be selected at the manufacturer’s discretion unless otherwise specified by the purchaser.
L5 TerminoLogy References
For definitions of terminology not specific-ally defined In this Standard, refer to ASME 818.12.
tinless otherwise specified, the standards referenced shall he the latest edition at the time of order placement
ASME 81.1, UnIfied Inch Screw Threads (UN and UNR Thread Form)
ASME 81.3, Screw Thread Gaging Systems (or Acceptahihty: Inch and Metric Screw Threads (UN, UNR, UNI, M. and MI)
ASME 818.12, Glossary of Terms for Mechanical Fasteners
ASME 81818, Quality Assurance for Fasteners
ASME 818,24, Part Identifying Number (PIN) Code System for 818 Fastener Products
ASME 8107 Sent’s, Standards for Hand Tools
Publisher; The American Society of Mechanical Engineers (ASME), Two Park Avenue, New lurk, NY 10016-5990 (
ASTM A563, Standard Specification for Carbon and Alloy Steel Nuts
AS’l’M P467, Standard Specification for Nonferrous Nuts for General Use
AS’l’M P594, Standard Specification for Stainless Steel Nuts
ASTM F1941/F1941M. Standard Specification for Electrodeposited Coatings on Mechanical Fasteners, Inch and Metric
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 nuts of nominal size 1f in. or smaller and 6% of the maximum width across flats for nuts larger than 1/ in.. regardless of leature size.
3.8.2 Square Nuts. The axis of tapped hole in square nuts shall be located at true position with respect to the axis olnut 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 Perpendicutarity
Hearing surface shall be flat and perpendicular to the axis of the threaded hole within the specified full indicator measurement (FIM) limit indicated In the tables. See Nonmandatory Appendix C icr measurement procedure.
3.10 Threads
3.10.1 Thread Standard. Threads shall meet the requirements of ASME 81.1.
3.10.2 Thread Class. Unless otherwise specified, threads shall be UrnIIed Standard. Class 2B,
3.10.3 Thread Senes. Thread series on nuts may be coarse (UNC), line (UNF), or 8 thread series (8UN).
3.10.4 Thread Gaging. Unless otherwise specified by the purchaser, gaging for screw thread dimensional acceptability shall be in accordance with Gaging System 21 as specified In ASME 813. Thread Gaging otiam Nuts. Efue to the three turn allowance and limited number ofthreads In fam nuts. NOT GO thread plug gages are not a reliable method for thread acceptance. Unless otherwise specified by the purchaser. jam nut thread acceptability shall be based on acceptance of the GO thread plug gage and nonacceptance of the NOT GO cylindrical plug gage to inspect minor diameter.
3.11 Material
Unless otherwise specifIed by the purchaser or elsewhere in this Standard, chemical and mechanical properties of steel nuts shall conform to Grade A of ASTM A563 or Grade 2 (square nuts only) of SAE J995. Nuts of oIlier materials such as corrosion resistant (stainless) steel, brass, bronze, and aluminum alloys shall have properties as agreed upon between the manufacturer and purchaser. Refer to ASTM F594 for information on corrosion resistant alloy steel requirements and ASTM F467 for information on nonferrous materials.
3.12 Finish
Unless otherwise specified, nuts shall be supplied with a natural (as-processed) finish. unplated or uncoated. II electroplated finishes are required, reference A.STM F1941. Other finishes may be specified as indicated in the applicable mechanical and performance standards.
3.13 Designation
3.13.1 Nuts shall be designated by the following data in the sequence shown. product name; dimensional standard, nominal size (fraction or decimal); threads per inch: basic width across flats (when applicable); mechanical and perfor. mance standard; and grade protective finish (including specification and thickness), if required.
(1) Square Nut. ASME 818.2.2. .13. ASTM A563 Grade A, Zinc Plated per ASTM F1941 Fe/Zn 3A
(2) lIes Nut. ASME 818.2.2. 4.l6. SAE J995 Grade 5. Steel
(3) Hex Thick Slotted Nut, ASME 8182.2, 1.000-8, ASTM F594 (Alloy Group 1) Corrosion Resistant Steel
(4) Small Pattern I Ir Machine Screw Nut. ASME 818.22, #10.32. Across Flats, Steel, Plain
3.132 For part identification numbers (PIN), refer to ASME 818.24.