FED-STD-H28 Screw-Thread Standards for Federal Services

1 FED-STD-H28 . 31 March 1978. Superseding NBS Handbook H28. PART I (1969). PART II (1957). PART III (1957). Federal STANDARD. Screw-Thread Standards FOR Federal Services . This standard was approved by the Commissioner, Federal Supply Service, General Services Administration, for the use of all Federal agencies. GOVERNMENT PRINTING OFFICE : 1978 - 261-423/1075. Orders for this publication are to be placed with General Services Administration, acting as an agent for the Superintendent of Documents. Single copies of this standard are available at the GSA Business Service Centers in Boston, New York, Philadelphia, Atlanta, Chicago, Kansas City, MO, Fort Worth, Houston, Denver, San Francisco, Los Angeles, and Seattle, WA. or from the General Services Administration, Specification and Consumer Information Distribution Branch, Bldg. 197, Washington Navy Yard, Washington, DC 20407.

2 Price cents each. FSC THDS. FED-STD-H28 . 31 March 1978. INFORMATION SHEET ON Federal Standards . This Federal Standard is issued in loose leaf form to permit the insertion or removal of new or revised pages and sections. All Users of Federal Standards should keep them up to date by inserting revised or new pages as issued and removing superseded and cancelled pages. New and revised pages will be issued under Change Notices which will be numbered consecutively and will bear the date of issuance. Change Notices should be retained and filed in front of the Standard until such time as they are superseded by a reissue of the entire Standard. NOTICE. From 1939, the Interdepartmental Screw-Thread Committee (ISTC), under the Chairmanship of the national Bureau of Standards (NBS), Department of Commerce had developed and published NBS Handbook H28, Screw-Thread Standards for Federal Services .

3 Section 487 of Title 40 of the Code states that the authority for development of Federal Standards for procurement purposes rests with the General Services Administration (GSA). In November 1976, the ISTC was terminated, and the General Services Administration (GSA) accepted the responsibility for NBS Handbook H28 and agreed to convert it and maintain it as a Federal Standard. The Standards which had been published as NBS Handbook H28, Part 1, Part II and Part III will now be promulgated as a fully coordinated FED-STD-H28 , maintaining the existing sections and identifying them with slant lines. For example, NBS Handbook H28, Part 1, Section 3 will be detailed standard FED-S-TD-H28/3 which must be procured individually. Military Custodians Preparing Activity ARMY - AR DLA-IS. NAVY - AS. AIR FORCE - 11 (Project No. THDS-0003). Civil Agency Coordinating Activity ACO FPI MSF.

4 AFS FRA NBS. BPA FSS PCD. FHW JFK RDS. FIS LRC TCS. ii FED-STD-H28 . 31 March 1978. CONTENTS. Page 1. PURPOSE AND 1. 1. 1. 2. 1. 3. DETAILED 1. 4. 2. 5. COMPARABLE INDUSTRY 3.. The text of this section is reprinted from the NBS HANDBOOK H28 with . minor editorial corrections. Pages 44, 48, 55 thru 63, 65 thru 68, 71, . 72, 73, 74. 75 and 80 thru 86 contain corrections indicated by an . asterisk.. Reorganization of the document from NBS HANDBOOK H28 to FED-STD-H28 . creates an editorial inconvenience, when maintaining continuity of cross . references amongst the pages, paragraphs, tables and figures of the . different sections. For this standard individual sections will be . numbered sequentially starting with (1) one. If the reprinted text . refers to another page, such as Page , this will be understood to mean . section 6 page 3.

5 All figures and tables will maintain the established . designations, prefixed with the section; Table and Figure to . identify their location in this standard. All appendices will be . incorporated in the basic document FED-STD-H28 with other general . information and will continue to be identified with the prefix A.. iii FED-STD-H28 . 31 March 1978. 1. PURPOSE AND SCOPE. Purpose. This standard establishes complete dimensional data requirements for screw threads including, as necessary, recommendations on gages, dies and taps and other items associated with the purchase/use of interchangeable threaded parts by Federal Government Agencies. So far as practicable, these data are intended to conform to generally accepted commercial practice, although certain special requirements of the Federal Services necessitate the inclusion of some Standards not generally applicable outside the Government.

6 References are cited throughout the text to the Standards promulgated by The american Standards Association (ASA) and the United States of America Standards Institute (USASI), now called The american national Standards Institute (ANSI). and to such other published Standards as are in agreement with the specifications herein. Scope. This standard includes the basic dimensional requirements for assembly, interchangeability, tensile strength, shear strength, fatigue strength and installation and removal torque of threaded products. Specific requirements for particular Screw-Thread Standards are covered by the Detail Standards (see Para 3). Supplements to the Detail Standards are covered in the Appendix of this document. (See Para 4). 2. APPLICATION. This standard is for use by all Federal Agencies for procurement of threaded parts.

7 3. DETAILED Standards . Detailed Standards for screw -Threads are identified as: FED-STD-H28 /1 - Nomenclature, Definitions, and Letter Symbols for screw Threads FED-STD-H28 /2 - unified thread Form and thread Series for Bolts, Screws, Nuts, Tapped Holes and General Applications FED-STD-H28 /3 - unified Threads of Special Diameter, Pitches, and Lengths of Engagement FED-STD-H28 /4 - Controlled Radius Root screw Threads, UNJ Symbol 1. FED-STD-H28 . 31 March 1978. FED-STD-H28 /5 - unified Miniature screw Threads FED-STD-H28 /6 - Gages and Gaging for unified screw Threads FED-STD-H28 /7 - american Standard Pipe Threads (except Dryseal and Hose Coupling Types). FED-STD-H28 /8 - Dryseal american Standard Pipe Threads FED-STD-H28 /9 - Gas Cylinder Valve Outlet and Inlet Threads FED-STD-H28 /10 - american national Hose Coupling and Fire-Hose Coupling Threads FED-STD-H28 /11 - Hose Connections For Welding and Cutting Equipment FED-STD-H28 /12 - Acme Threads FED-STD-H28 /13 - Stub Acme Threads FED-STD-H28 /14 - national Buttress Threads FED-STD-H28 /15 - american Standard Rolled Threads For screw Shells of Electric Lamp Holders and For screw Shells of Unassembled Lamp Bases FED-STD-H28 /16 - Microscope Objective and Nosepiece Threads, - 36 AMO.

8 FED-STD-H28 /17 - Surveying Instrument Mounting Threads FED-STD-H28 /18 - Photographic Equipment Threads FED-STD-H28 /19 - Miscellaneous Threads (a) FED-STD-H28 /20 -Inspection Methods For Acceptability of UN, UNR, UNJ, M and MJ screw -Threads (b) FED-STD-H28 /21 -Metric screw -Threads (a) FED-STD-H28 /22 -Metric Screw-Thread Gages 4. APPENDIX - The following supplements to the detailed Standards are included in this document. A1 - american national Form of thread Series for Bolts, Machine Screws, Nuts, Tapped Holes and General Applications (Inactive for new design). (a) Not issued as of 31 March 1978. (b) Initial release as INTERIM FED-STD-00H28/21 (DLA-IS) dated 31 May 1977. 2. FED-STD-H28 . 31 March 1978. A2 - american national screw Threads of Special Diameters, Pitches, and Lengths of Engagement (Deleted from 1969 issue of Hand book H28).

9 A3 - Recommended Hole Size Limits Before Threading and Tap Drill Sizes A4 - Methods of Wire Measurements of Pitch Diameter of 600 Threads A5 - Design of Special Threads A6 - References (Deleted from 1969 issue of Handbook H28). A7 - Supplementary Pipe Threads Information A8 - Geometry of Taper screw Threads A9 - Extent of Usage of the american national Fire-Hose Coupling Threads on Couplings and Nipples used with 211 inch nominal Size Fire-Hose A10 - Wrench Openings A11 - Class 5 Interference - Fit Threads A12 - The Tightening of Threaded Fasteners to Proper Tension A13 - Three Wire method of measurement of Pitch Diameter of 290 Acme, 29. Stub Acme, and Buttress Threads A14 - Metric screw thread Standards (Superseded by FED-STD-00H28/21. (DLA-IS)). 5. COMPARABLE INDUSTRY Standards : but not Identical FED-STD-H28 /1 - ANSI FED-STD-H28 /2 - ANSI FED-STD-H28 /3 - ANSI (a).

10 FED-STD-H28 /4 - FED-STD-H28 /5 - FED-STD-H28 /6 - ANSI 3. FED-STD-H28 . 31 March 1978. FED-STD-H28 /7 - ANSI FED-STD-H28 /8 - ANSI FED-STD-H28 /9 - ANSI Std V-1. FED-STD-H28 /10 - ANSI or NFPA No. 194. FED-STD-H28 /11 - CGA. FED-STD-H28 /12 - ANSI B1-5. FED-STD-H28 /13 - ANSI FED-STD-H28 /14 - ANSI B1-9. FED-STD-H28 /15 - ANSI FED-STD-H28 /16 - ANSI FED-STD-H28 /17 - FED-STD-H28 /18 - ANSI PH3-7, 10, 12, 24. FED-STD-H28 /19 - FED-STD-H28 /20 - ANSI (a) (a). FED-STD-H28 /21 - ANSI , Appendix A4 - ANSI Appendix A7 - ANSI , , Appendix A10 - ANSI Appendix A11 - ANSI Appendix A13 - ANSI , , (a) Not Issued as of 31 March 1978. 4. FED-STD-H28 . 31 March 1978. ANSI, USASI, ASA, NFPA Publications american national Standards Institute 1430 Broadway New York, NY 10018. national Fire Protection Association 470 Atlantic Avenue Boston, MA 02210. CGA Publications Compressed Gas Association, Inc.