ASME B1.1 2024

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ASME B1.1-2024 Unified Inch Screw Threads (UN, UNR, and UNJ Thread Forms)

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ASME	2024

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Description

This Standard specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads. (In order to emphasize that unified screw threads are based on inch modules, they may be denoted unified inch screw threads.) Several variations in thread form have been developed for unified threads; however, this Standard covers only [Unified] UN and UNR [external threads only] thread forms. For easy reference, a metric translation of this Standard has been incorporated as Nonmandatory Appendix C. Nonmandatory Appendices A through E contain useful information that is supplementary to the sections of this Standard.

PDF Catalog

PDF Pages	PDF Title
4	CONTENTS
6	FOREWORD
9	ASME B1 COMMITTEE ROSTER
10	CORRESPONDENCE WITH THE B1 COMMITTEE
12	1 GENERAL 1.1 Scope 1.2 Unified Screw Thread Standards 1.3 Thread Forms 1.4 Interchangeability 1.5 Designations 1.6 References
13	Figures Figure 1 Illustration of Assembly Interference of UNJ-3A Thread and UN-3B Thread in the Maximum Material Condition
14	1.7 Acceptability 1.8 Reference Temperature 1.9 Units of Measure 1.10 Federal Government Use 2 SCREW THREAD PROFILE 2.1 Scope 2.2 Basic Profile 2.3 Design Profiles
15	Figure 2 Basic Profile for UN and UNR Screw Threads Figure 3 Basic Profile for UNJ Screw Threads
16	Figure 4 Root Radius of UNJ External Thread
17	Figure 5 Disposition of Diametral Tolerances, Allowance, and Crest Clearance for Unified Inch Screw Thread Series UN, Classes 1A, 2A, 1B, and 2B
18	Figure 6 Disposition of Diametral Tolerances and Crest Clearance for Unified Inch Screw Thread Series UN, Classes 3A and 3B
19	Figure 7 Disposition of Diametral Tolerances, Allowance, and Crest Clearance for Unified Inch Screw Thread Series UNR, Classes 1A and 2A, and Series UN, Classes 1B and 2B
20	Figure 8 Disposition of Diametral Tolerances and Crest Clearance for Unified Inch Screw Thread Series UNR, Class 3A and Series UN, Class 3B
21	2.4 Formulas and Nomenclature 3 SCREW THREAD SERIES 3.1 Thread Series Definition 3.2 Order of Selection 3.3 Coarse-Thread Series Applications 3.4 Fine-Thread Series Applications 3.5 Extra-Fine-Thread Series Applications
22	Figure 9 External UNJ Thread Design Profile and Tolerances
23	Figure 10 Disposition of Diametral Tolerances, Allowance, and Crest Clearance for Unified Inch Screw Thread Series UNJ, Classes 2A and 2B
24	Figure 11 Disposition of Diametral Tolerances and Crest Clearance for Unified Inch Screw Thread Series UNJ, Classes 3A and 3B
25	Figure 12 Internal UNJ Thread Design Profile and Tolerances Figure 13 Basic Method of Designating Screw Threads
26	3.6 Constant-Pitch-Thread Series Applications 3.7 Fine Threads for Thin-Wall Tubing 4 SCREW THREAD CLASSES 4.1 Thread Classes
27	Tables Table 1 Standard Series Threads (UN, UNR, and UNJ)
29	Table 2A Limits of Size for Standard Series External Threads (UN, UNR, and UNJ)
58	Table 2B Limits of Size for Standard Series Internal Threads (UN and UNJ)
91	5 SCREW THREAD ALLOWANCE AND TOLERANCE 5.1 Allowance 5.2 Pitch Diameter Tolerance, All Classes
92	5.3 Special Lengths of Engagement, LE 5.4 Minor Diameter Tolerance and Allowance for External Threads 5.5 Major Diameter Tolerance for Internal Threads 5.6 Minor Diameter Tolerance and Length of Engagement for Internal Threads
93	Table 3 Allowable Variations in Lead and Equivalent Change in Functional Diameter
113	5.7 Disposition of Allowance and Tolerance 5.8 Formulas for Allowance and Tolerance
114	5.9 Lead and Flank Angle Tolerances 5.10 Coated or Plated Threads 5.11 Circular Runout
115	Table 4 Increments in Pitch Diameter Tolerance — Class 2A (PD Tolerance = 0.0015 3√D + 0.0015√LE + 0.015 3√p2)
117	Table 5 Basic Profile and Constants for Calculation Formulas of Thread Dimensions, in.
121	6 SCREW THREAD DESIGNATION 6.1 Basic Method of Designating 6.2 Method of Designating Coated Threads
122	6.3 Method of Designating Left-Hand Threads
123	6.4 Method of Designating Special Unified Threads 6.5 Designations for Other Threads 6.6 Method of Designating Threads Having Special Length of Engagement
124	6.7 Method of Designating Threads Having Modified Crests 7 DIMENSIONAL ACCOMMODATION OF COATING OR PLATING FOR 60-DEG THREADS 7.1 Introduction
125	7.2 Strength 7.3 Electrodeposited Coatings 7.4 Other Considerations 7.5 Material Limits for Coated Threads 7.6 Dimensional Effects of Coating 7.7 External Thread With Allowance Available for Coating 7.8 External Thread With No Allowance for Coating
126	Figure 14 Ratio of Pitch Diameter Change to Thickness of Coating on 60-deg Threads
127	Figure 15 Effect of Electrodeposited Coating on 60-deg External Threads
129	7.9 Internal Threads
130	8 LIMITS OF SIZE FOR STANDARD (UN, UNR, AND UNJ) AND SPECIAL (UNS, UNRS, AND UNJS) SERIES OF THREADS 8.1 Standard Series 8.2 Limits of Size 8.3 Formulas for Limits of Size
131	Figure 16 Application of General Thread Symbols
134	8.4 Example of Calculations From Formulas 9 THREAD FORM TOLERANCES 9.1 Form Variation 9.2 Lead and Flank Angle Acceptance
135	10 FORMULAS AND NOMENCLATURE FOR THREAD FORM
136	11 TABLES OF BASIC DIMENSIONS 11.1 Table Content 11.2 Thread Series
137	Table 6 Basic Dimensions for Coarse-Thread Series (UNC, UNRC, and UNJC)
139	Table 7 Basic Dimensions for Fine-Thread Series (UNF, UNRF, and UNJF)
140	Table 8 Basic Dimensions for Extra-Fine-Thread Series (UNEF, UNREF, and UNJEF)
142	Table 9 Basic Dimensions for 4-Thread Series (UN, UNR, and UNJ)
144	Table 10 Basic Dimensions for 6-Thread Series (UN, UNR, and UNJ)
146	Table 11 Basic Dimensions for 8-Thread Series (UN, UNR, and UNJ)
148	Table 12 Basic Dimensions for 12-Thread Series (UN, UNR, and UNJ)
151	Table 13 Basic Dimensions for 16-Thread Series (UN, UNR, and UNJ)
154	Table 14 Basic Dimensions for 20-Thread Series (UN, UNR, and UNJ)
156	Table 15 Basic Dimensions for 28-Thread Series (UN, UNR, and UNJ)
157	Table 16 Basic Dimensions for 32-Thread Series (UN, UNR, and UNJ)
158	Table 17A Outline Guide for Determining Limits of Size of External Threads Table 17B Outline Guide for Determining Limits of Size of Internal Threads
159	Table 18A Examples of External 2A Screw Threads
161	Table 18B Example of External 3A Screw Threads
164	Table 18C Examples of Internal 2B Screw Threads
166	Table 18D Example of Internal 3B Screw Threads
169	Table 19 Allowable Variation in 30-deg Basic Half Angle of External and Internal Screw Threads
170	Table 20 Nomenclature
172	NONMANDATORY APPENDICES NONMANDATORY APPENDIX A TERMINOLOGY AND IDENTIFICATION OF UNIFIED INCH SCREW THREADS A-1 TERMINOLOGY A-2 IDENTIFICATION
173	Figure A-1 Identification of 60-deg Inch Screw Threads Within the Scope of the ASME B1 Committee
174	Table A-1 Identification of 60-deg Inch Screw Threads Within the Scope of the ASME B1 Committee
175	NONMANDATORY APPENDIX B THREAD STRENGTH DESIGN FORMULAS B-1 THREAD TENSILE STRESS AREA FOR UN, UNR, AND UNJ THREADS B-2 THREAD SHEAR DATA FOR UN, UNR, AND UNJ THREADS B-3 LENGTH OF THREAD ENGAGEMENT
176	NONMANDATORY APPENDIX C UNIFIED INCH SCREW THREADS — METRIC TRANSLATION
177	NONMANDATORY APPENDIX D SPECIAL THREADS
178	Table D-1 Limits of Size for Selected Combinations of UNS/UNRS Series Threads
186	NONMANDATORY APPENDIX E CHANGES TO ASME B1.1-1989, TABLES 3A AND 3B
187	Table E-1 Limits of Size for Standard Series Internal and External Threads as Listed in Table 3A of ASME B1.1-1989
198	Table E-2 Limits as Listed in Table D-1 (Formerly 3B) Prior to ASME B1.1-2003 Edition
204	NONMANDATORY APPENDIX F SPECIAL LENGTHS OF ENGAGEMENT SPECIFICATIONS AND DESIGNATIONS F-1 SPECIAL LENGTHS OF ENGAGEMENT, LE, SPECIFICATIONS
205	F-2 METHOD OF DESIGNATING THREADS HAVING SPECIAL LENGTH OF ENGAGEMENT