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.

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4	CONTENTS
6	FOREWORD
8	ASME B1 COMMITTEE ROSTER
9	CORRESPONDENCE WITH THE B1 COMMITTEE
10	1 GENERAL 1.1 Scope 1.2 Unified Screw Thread Standards 1.3 Thread Forms 1.4 Interchangeability 1.5 Designations 1.6 References
11	1.7 Acceptability 1.8 Reference Temperature Figures Figure 1 Illustration of Assembly Interference of UNJ-3A Thread and UN-3B Thread in theMaximum Material Condition
12	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 Figure 2 Basic Profile for UN and UNR Screw Threads
13	Figure 3 Basic Profile for UNJ Screw Threads Figure 4 Root Radius of UNJ External Thread
14	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
15	Figure 5 Disposition of Diametral Tolerances, Allowance, and Crest Clearance for Unified Inch Screw Thread Series UN, Classes 1A, 2A, 1B, and 2B
16	Figure 6 Disposition of Diametral Tolerances and Crest Clearance for Unified Inch Screw Thread Series UN, Classes 3A and 3B
17	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
18	Figure 8 Disposition of Diametral Tolerances and Crest Clearance for Unified Inch Screw Thread Series UNR, Class 3A and Series UN, Class 3B
19	3.4 Fine-Thread Series Applications 3.5 Extra-Fine-Thread Series Applications 3.6 Constant-Pitch-Thread Series Applications Figure 9 External UNJ Thread Design Profile and Tolerances
20	Figure 10 Disposition of Diametral Tolerances, Allowance, and Crest Clearance for Unified Inch Screw Thread Series UNJ, Classes 2A and 2B
21	Figure 11 Disposition of Diametral Tolerances and Crest Clearance for Unified Inch Screw Thread Series UNJ, Classes 3A and 3B
22	Tables Table 1 Standard Series Threads (UN, UNR, and UNJ)
24	Table 2A Limits of Size for Standard Series External Threads (UN, UNR, and UNJ)
54	Table 2B Limits of Size for Standard Series Internal Threads (UN and UNJ)
86	3.7 Fine Threads for Thin-Wall Tubing 4 SCREW THREAD CLASSES 4.1 Thread Classes 5 SCREW THREAD ALLOWANCE AND TOLERANCE 5.1 Allowance 5.2 Pitch Diameter Tolerance, All Classes
87	Figure 12 Internal UNJ Thread Design Profile and Tolerances
88	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
89	Table 3 Allowable Variations in Lead and Equivalent Change in Functional Diameter
108	5.7 Disposition of Allowance and Tolerance 5.8 Formulas for Allowance and Tolerance
109	Table 4 Increments in Pitch Diameter Tolerance — Class 2A (PD Tolerance = 0.0015 3 D + 0.0015 LE + 0.015 3 P2)
111	Table 5 Basic Profile and Constants for Calculation Formulas of Thread Dimensions, in.
115	5.9 Lead and Flank Angle Tolerances 5.10 Coated or Plated Threads 5.11 Circular Runout 6 SCREW THREAD DESIGNATION 6.1 Basic Method of Designating
116	6.2 Method of Designating Coated Threads Figure 13 Basic Method of Designating Screw Threads
117	6.3 Method of Designating Left-Hand Threads 6.4 Method of Designating Special Unified Threads 6.5 Designations for Other Threads
118	6.6 Method of Designating Threads Having Special Length of Engagement 6.7 Method of Designating Threads Having Modified Crests
119	7 DIMENSIONAL ACCOMMODATION OF COATING OR PLATING FOR 60-DEG THREADS 7.1 Introduction 7.2 Strength 7.3 Electrodeposited Coatings 7.4 Other Considerations 7.5 Material Limits for Coated Threads
120	7.6 Dimensional Effects of Coating 7.7 External Thread With Allowance Available for Coating 7.8 External Thread With No Allowance for Coating
121	Figure 14 Ratio of Pitch Diameter Change to Thickness of Coating on 60-deg Threads
122	Figure 15 Effect of Electrodeposited Coating on 60-deg External Threads
123	7.9 Internal Threads
124	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
126	8.4 Example of Calculations From Formulas 9 THREAD FORM TOLERANCES 9.1 Form Variation 9.2 Lead and Flank Angle Acceptance
127	Table 6 Basic Dimensions for Coarse-Thread Series (UNC, UNRC, and UNJC)
128	Table 7 Basic Dimensions for Fine-Thread Series (UNF, UNRF, and UNJF)
129	Table 8 Basic Dimensions for Extra Fine-Thread Series (UNEF, UNREF, and UNJEF)
130	Table 9 Basic Dimensions for 4-Thread Series (UN, UNR, and UNJ)
132	Table 10 Basic Dimensions for 6-Thread Series (UN, UNR, and UNJ)
134	Table 11 Basic Dimensions for 8-Thread Series (UN, UNR, and UNJ)
136	Table 12 Basic Dimensions for 12-Thread Series (UN, UNR, and UNJ)
139	Table 13 Basic Dimensions for 16-Thread Series (UN, UNR, and UNJ)
142	Table 14 Basic Dimensions for 20-Thread Series (UN, UNR, and UNJ)
144	Table 15 Basic Dimensions for 28-Thread Series (UN, UNR, and UNJ)
145	Table 16 Basic Dimensions for 32-Thread Series (UN, UNR, and UNJ)
146	Table 17A Outline Guide for Determining Limits of Size of External Threads Table 17B Outline Guide for Determining Limits of Size of Internal Threads
147	Table 18A Examples of External Screw Threads
149	Table 18B Examples of Internal Screw Threads
151	10 FORMULAS AND NOMENCLATURE FOR THREAD FORM 11 TABLES OF BASIC DIMENSIONS 11.1 Table Content 11.2 Thread Series
152	Figure 16 Application of General Thread Symbols
154	Table 19 Allowable Variation in 30-deg Basic Half Angle of External and Internal Screw Threads
155	Table 20 Nomenclature
157	Figure A-1 Identification of 60-deg Inch Screw Threads Within the Scope of the ASME B1 Committee NONMANDATORY APPENDICES NONMANDATORY APPENDIX A TERMINOLOGY AND IDENTIFICATION OF UNIFIED INCH SCREW THREADS A-1 TERMINOLOGY A-2 IDENTIFICATION
158	Table A-1 Identification of 60-deg Inch Screw Threads Within the Scope of the ASME B1 Committee
159	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
160	NONMANDATORY APPENDIX C UNIFIED INCH SCREW THREADS — METRIC TRANSLATION
161	NONMANDATORY APPENDIX D SPECIAL THREADS
162	Table D-1 Limits of Size for Selected Combinations of UNS/UNRS Series Threads
170	NONMANDATORY APPENDIX E CHANGES TO ASME B1.1-1989, TABLES 3A AND 3B
171	Table E-1 Limits of Size for Standard Series Internal and External Threads as Listed in Table 3A of ASME B1.1-1989
183	Table E-2 Limits as Listed in Table D-1 (Formerly 3B) Prior to ASME B1.1-2003 Edition
189	NONMANDATORY APPENDIX F SPECIAL LENGTHS OF ENGAGEMENT SPECIFICATIONS AND DESIGNATIONS F-1 SPECIAL LENGTHS OF ENGAGEMENT, LE, SPECIFICATIONS
190	F-2 METHOD OF DESIGNATING THREADS HAVING SPECIAL LENGTH OF ENGAGEMENT

Published By	Publication Date	Number of Pages
ASME	2019	194


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Standard Title	ASME B1.1-2019: Unified Inch Screw Threads (UN, UNR, and UNJ Thread Forms)
Published Code	ASME
Publication Date	2019
Pages Count	194

ASME B1.1 2019

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