ASME B1.1-2003 pdf download

ASME B1.1-2003 pdf download.Unified Inch Screw Threads.
1 GENERAL 1.1 Scope 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 UN and UNR thread forms. For easy reference, a metric translation of this Stan- dard has been incorporated as Nonmandatory Appen- dix C. Nonmandatory Appendices A through E contain useful information that is supplementary to the sections of this Standard. 1.2 Unified Screw Thread Standards The standards for unified screw threads published in this Standard are in agreement with formal standards of the International Organization for Standardization for diameter-pitch combinations, designations, and tol- erances for 60 deg triangular form inch screw threads. Unified screw threads had their origin in an accord signed in Washington, D.C., on November 18, 1948, by representatives of standardizing bodies of Canada, the United Kingdom, and the United States, and have subse- quently superseded American National screw threads. 1.3 UN and UNR Screw Threads UNR applies only to external threads; the difference between UN and UNR threads, in addition to designa- tion, is that a flat or optional rounded root contour is specified for UN threads, while only a rounded root contour is specified for UNR threads. 1.4 Interchangeability Unified (UN/UNR) and its predecessor, American National screw threads, have substantially the same thread form, and threads of both standards having the same diameter and pitch are mechanically interchange- able. The principal differences between these standards relate to the application of allowances, the variation of tolerances with size, differences in the amounts of pitch diameter tolerances for external and internal threads, and differences in thread designations. Unified inch and 1 ISO metric screw threads are not mechanically inter- changeable. 1.5 Designations Unified thread sizes (specific combinations of diame- ter and pitch) are identified by the letter combination “UN” in the thread symbol. In the unified standards, the pitch diameter tolerances for external threads differ from those for internal threads; for this reason the letter “A” is used in the thread symbol to denote an external thread and the letter “B,” an internal thread. Where the letters “U,” “A,” or “B” do not appear in the thread designation, the threads conform to the outdated Ameri- can National screw threads. Details regarding thread designations are given in para. 6. 1.6 Reference Documents The latest issues of the following documents form a part of this Standard to the extent specified herein. When the following American National Standards referred to in this Standard are superseded by a revision approved by the American National Standards Institute, Inc., the revision should apply. ASME B1.2, Gages and Gaging for Unified Inch Screw Threads ASME B1.3, Screw Thread Gaging Systems for Dimen- sionalAcceptability — Inch and Metric Screw Threads ASME B1.7, Nomenclature, Definitions, and Letter Sym- bols for Screw Threads ASME B1.30, Screw Threads — Standard Practices for Calculating and Rounding Dimensions ASME B47.1, Gage Blanks ASME B94.11, Twist Drills ASME Y14.5, Dimensioning and Tolerancing Publisher: The American Society of Mechanical Engi- neers (ASME International), Three Park Avenue, New York, NY 10016-5990; Order Department: 22 Law Drive, Box 2300, Fairfield, NJ 07007-2300 ISO 68, General Purpose Screw Threads — Basic Profile Publisher: International Organization for Standardiza- tion (ISO), 1 rue de Varembe´, Case Postale 56, CH- 1211, Gene`ve 20, Switzerland/Suisse
1.7 Acceptability Acceptability of product threads shall be in accor- dance with ASME B1.3. Gages and gaging shall be in accordance with ASME B1.2. 1.8 Reference Temperature The reference temperature is 68°F for dimensions defined by this system. 1.9 Units of Measure All dimensions in this Standard, including all tables, are in inches unless otherwise specified. 1.10 Federal Government Use When this Standard is approved by the Department of Defense and federal agencies and is incorporated into FED-STD-H28/2, Screw-Thread Standards for Federal Services, para. 2, the use of this Standard by the federal government will be subject to all the requirements and limitations of FED-STD-H28/2. 2 SCREW THREAD PROFILE 2.1 Scope The basic profile and design profiles are defined in this paragraph and are the basis ofall thread dimensions given in this Standard. 2.2 Basic Profile The basic profile for UN screw threads is identical to that for UNR screw threads and is shown in Fig. 1. Profile applies to an axial plane. For reference, the basic profile for UN and UNR screw threads is identical to that for ISO metric screw threads shown in ISO 68. 2.3 Design Profiles The design profiles define the maximum-materialcon- ditions for external and internal threads with no allow- ance and are derived from the basic profile. The design profiles of both external and internal screw threads vary from the basic profile.