1、BRITISH STANDARD BS4929-1: 1973 Incorporating Amendment No.1 Specification for Steel hexagon prevailing-torque type nuts Part 1: Metric series UDC 621.822.31BS4929-1:1973 This British Standard, having beenapproved by the MechanicalEngineering IndustryStandards Committee,was published underthe author
2、ityof the Executive Boardon 15 June 1973 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference MEE/60, MEE/60/12 Draft for comment69/4810 ISBN 0 580 07641 5 Co-operating organizations The Mechanical Engineering Industry Standards Committee, under whose sup
3、ervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: The Government departments and scientific and industrial organizations marked with an asterisk in the above list, together with the followin
4、g, were directly represented on the committee entrusted with the preparation of this British Standard: Associated Offices Technical Committee Engineering Equipment Users Association* Association of Consulting Engineers Gas Council Association of Hydraulic Equipment Institution of Civil Engineers Man
5、ufacturers Ltd.* Institution of Gas Engineers Association of Mining Electrical and Institution of Heating and Ventilating Mechanical Engineers Engineers British Compressed Air Society Institution of Mechanical Engineers British Electrical and Allied Institution of Mechanical Engineers Manufacturers
6、Association (Automobile Division) British Gear Manufacturers Association Institution of Production Engineers* British Internal Combustion Engine London Transport Executive Manufacturers Association Machine Tool Trades Association* British Mechanical Engineering Confederation Ministry of Defence Brit
7、ish Pump Manufacturers Association Ministry of Defence, Army Department British Steel industry* National Coal Board Crown Agents for Overseas Governments and National Physical Laboratory (Department of Administrations Trade and Industry) Department of Employment Process Plant Association Department
8、of the Environment* Railway Industry Association of Great Britain Department of Trade and Industry Royal Institute of British Architects Department of Trade and Industry Telecommunications Engineering National Engineering Laboratory* Manufacturing Association Electricity Council, the Central Electri
9、city Water Tube Boilermakers Association Generating Board and the Area Boards in England and Wales Black Bolt and Nut association of Great Power Generation Association Britain Precision Bolt and Nut Institute British Bolt, Nut, Screw and Rivet Federation Rolled Thread Screw Association British Const
10、ructional Steelwork Association Scientific Instrument Manufacturers British Railways Board Association of Great Britain Constructional Steel Research and Society of Motor Manufacturers and Development Organisation Traders Ltd. Fasteners and Turned Parts Institute Washer Manufacturers Association of
11、Institute of Iron and Steel Wire Manufacturers Great Britain Ministry of Defence, Navy Department Individual Manufacturers Post Office Amendments issued since publication Amd. No. Date of issue Comments 2105 October 1976 Indicated by a sideline in the marginBS4929-1:1973 BSI 07-1999 i Contents Page
12、Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definition 1 3 Property class designation system 1 4 Material and manufacture of steel nuts 1 5 Dimensional requirements 1 6 Mechanical requirements 2 7 Performance requirements 2 8 Test methods 2 9 Marking and identification 4 10
13、 Inspection 4 11 Complete designation for the purpose of an enquiry or order 4 Table 1 Mechanical properties of steel nuts 2 Table 2 Dimensions of metric series prevailing-torque type nuts 5 Table 3 Proof load, clamp load and prevailing-torques (coarse pitch series) property class8 6 Table 4 Proof l
14、oad, clamp load and prevailing-torques (coarse pitch series) property class12 7 Table 5 Test washer, metric series 8 Publications referred to Inside back coverBS4929-1:1973 ii BSI 07-1999 Foreword This Part of this British Standard has been prepared under the authority of the Mechanical Engineering
15、Industry Standards Committee as a result of requests received from industry for the provision of a new standard covering steel hexagon prevailing-torque type nuts. This type of product has been standardized in the USA over a period of many years and the USA has submitted a draft ISO proposal, coveri
16、ng both metric and inch series products, which has been adopted by ISO/TC2, “Bolts, nuts and accessories”, as the basis for ISO draft Recommendations. Where possible, the provisions of the following ISO Recommendations and ISO Standard have also been incorporated in the text of this standard: This s
17、tandard purposely relates to metric series products only, since it was felt that confusion might arise if inch series products having similar performance, functional and material requirements (but differing with regard to dimensional and identification characteristics), were included in a composite
18、document. Thus, not withstanding the amount of duplication involved, it was considered advisable to prepare similar but separate documents for the metric and inch series products. The dimensional and identification requirements in this document are based on current ISO metric practice. NOTETwo prope
19、rty classes,8 and12 from ISO/R898/II have been included in this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer
20、immunity from legal obligations. ISO Recommendation R272, “Hexagon bolts and nuts. Metric series. Widths across flats, heights of heads, thicknesses of nuts”. ISO Recommendation R733, “Hexagon bolts and nuts. Metric series. Tolerances on widths across flats. Widthsacross corners”. ISO Recommendation
21、 R898/I, “Mechanical properties of fasteners. PartI.Bolts, screws and studs”. ISO Recommendation R898/II, “Mechanical properties of fasteners. PartII.Nuts with specified proof load values”. ISO Recommendation R898/III, “Mechanical properties of fasteners. PartIII.Marking of bolts, screws, studs andn
22、uts”. ISO Standard ISO2320, “Prevailing-torque type steel hexagon locknuts. Mechanical and performance properties”. ISO Standard ISO2358, “Prevailing-torque type steel hexagon locknuts. Dimensions. Metric units”. Summary of pages This document comprises a front cover, an inside front cover, pagesi a
23、ndii, pages1 to8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS4929-1:1973 BSI 07-1999 1 1 Scope 1.1 This part of this British Standard sp
24、ecifies the general dimensions and tolerances of prevailing-torque type nuts with ISO metric threads in diameters from3mm to36mm inclusive. 1.2 Mechanical properties and performance requirements are given only in respect of steel nuts, with or without non-metallic inserts such as nylon, which are no
25、t to be used for special applications such as those requiring weldability, corrosion resistance or the ability to withstand temperatures above300C(120 C for nuts with non-metallic inserts) or below 50 C. 1.3 Two nut heights are specified, designated “normal” and “high” respectively. The particular d
26、esign used by the nut manufacturer will determine which of these height categories is applicable. 1.4 Unless otherwise specified by the purchaser either normal or high nuts, with or without non-metallic inserts, may be supplied. NOTEThe titles of the British Standards referred to in this standard ar
27、e listed on the inside back cover. 2 Definition For the purposes of this British Standard the following definition applies: prevailing-torque type nut a nut which is frictionally resistant to rotation due to a self-contained prevailing-torque feature and not because of a compressive load developed a
28、t assembly against the bearing surface of the nut. The term prevailing-torque is not intended to imply an indefinite permanence of fixity 3 Property class designation system 3.1 This standard includes property classes specified in this standard for metric series steel hexagon prevailing-torque type
29、nuts which shall be designated by the numbers “8” and “12” as shown below. The designation number of the property class is equal to one tenth of the specified proof load stress in kilogrammes-force per square millimetre (SI units given for reference). This proof load stress corresponds to the minimu
30、m tensile strength of a bolt or screw with which the nut should be assembled so as to ensure the loading capacity of the bolted connection up to the minimum tensile strength of the bolt. NOTEThe designation system adopted is identical with that used for steel nuts in BS3692 and ISO/R898/II. 4 Materi
31、al and manufacture of steel nuts 4.1 Material. Nuts shall be made of carbon or alloy steel of a grade adequate for the nut to meet the mechanical and performance requirements of this standard. The prevailing-torque element of insert design nuts may be of a material other than steel. 4.2 Heat treatme
32、nt. Class8 nuts may be heat treated as necessary. Class 12 nuts shall be heat treated to meet the mechanical and performance requirements of this standard. 4.3 Finish. Nuts shall be finished plain (bare metal) or with a protective coating (electro-deposited plating or chemical conversion coating) as
33、 specified on the order. Plating shall be in accordance with BS3382 or BS1706. In order to comply with the stated performance requirements of this standard nuts shall, where necessary, be provided with a supplementary lubricant which shall be clean and dry to the touch. 5 Dimensional requirements 5.
34、1 Basic dimensions. Nuts shall be in accordance with the dimensions given in Table 2. The portion of the nut containing the prevailing-torque feature may have a special contour within the maximum permitted width across flats and thickness. The minimum width across flats shall not apply at a depresse
35、d portion of the nut at the prevailing-torque feature. Property class Proof load stress (S p ) N/mm 2a 8 785 12 1177 NOTEIf in exceptional circumstances it is necessary to combine one of these quality classes of nuts with a bolt of lower class, the performance characteristics may be significantly al
36、tered. a 1 N/mm 2 =1 MN/m 2 =1/MPaBS4929-1:1973 2 BSI 07-1999 5.2 Thread form, series and tolerances. The threads of the nuts shall be to the ISO metric coarse pitch series in accordance with BS3643-2. The tolerance class shall be “6H”. The portion of the nut containing the prevailing-torque element
37、 need not be in accordance with this requirement. 5.3 Thread start. The nuts shall assemble a minimum of one full turn by hand on a basic GO thread plug gauge. The plug gauge shall be chamfered at 45 to at least the full depth of the thread. 5.4 Defects. The nuts shall be free from burrs, loose scal
38、e, sharp edges, and all other defects that might adversely affect their service. 6 Mechanical requirements 6.1 Proof load. The nuts shall withstand the proof stresses specified for the applicable class in Table 3 and Table 4 when tested as specified in8.1. 6.2 Hardness. The nuts shall have a hardnes
39、s not in excess of the hardness specified for the applicable class in Table 1 when tested as specified in8.2. Table 1 Mechanical properties of steel nuts 7 Performance requirements 7.1 Prevailing-torque. The prevailing-torque developed by the nuts during their first installation, or any subsequent i
40、nstallation, or removal shall not exceed the maximum first installation torque specified in Table 3 and Table 4 when tested as specified in8.3. In addition, the maximum and minimum prevailing-torques developed by nuts during their first and fifth removals shall not be less than the “highest” and “lo
41、west” reading removal torques specified in Table 3 and Table 4 when tested as specified in8.3. 7.2 Definition. The prevailing-torque developed by a nut is the torque necessary to rotate the nut on its mating externally threaded component, with the torque being measured while the nut is in motion, an
42、d with no axial load in the mating component. 8 Test methods 8.1 Proof load test. The test sample nut shall be assembled on a test bolt (see8.1.1) or on a hardened mandrel (see8.1.2) with a minimum of three full threads projecting through the nut. For referee test purposes, the hardened mandrel shal
43、l be used. The maximum torque occurring during the assembly of the nut on the test bolt or mandrel shall be recorded. A tensile load equal to the specified proof load for the nut, as given in Table 3 and Table 4, shall be applied through the test bolt or mandrel against the nut bearing surface in an
44、 axial direction. The nut shall resist this load without thread stripping or rupture. The torque necessary to remove the nut from the test bolt or mandrel shall not exceed the maximum torque occurring during assembly. 8.1.1 Test bolt. The bolt used for proof load testing a nut shall have threads in
45、accordance with BS3643-2, tolerance class “6g”. The test bolt shall have a yield strength in excess of the specified proof load of the nut being tested. Property class 8 12 Proof load stress a(S p ), min. N/mm 2 785 N/mm 2 1177 Vickers hardness HV, max. 310 370 Rockwell hardness bHRC, max. 32.2 38.8
46、 Brinell hardness bHB, max. 294.5 351.5 a The proof load is calculated by multiplying the proof load stress by the tensile stress area of the bolt. b The conversion from Vickers hardness into Rockwell hardness and Brinell hardness has been taken from BS860.BS4929-1:1973 BSI 07-1999 3 8.1.2 Hardened
47、mandrel. The hardened mandrel used for proof load testing a nut shall have threads in accordance with BS3643, tolerance class “5h”, except that the tolerance on the major diameter shall be the last quarter of the “6g” range on the minimum material side for ISO metric screw threads. The mandrel shall
48、 be heat treated to a hardness of Rockwell C45-50 or Brinell HB430-486. 8.2 Hardness test. The hardness of a sample nut shall be determined on a suitable surface. The preparation of the test specimen and the method of performing the test shall be in accordance with the following British Standards: 8
49、.3 Prevailing-torque test. The prevailing-torque test shall be conducted at room temperature using a load measuring device (see8.3.1). A test bolt (see8.3.2) shall be inserted in the load measuring device, a hardened washer (see8.3.3) placed on the bolt and the sample nut then assembled on the bolt. The nut shall be advanced on the bolt until a minimum of two full bolt threads protrude through the nut. At that time, the maximum torque occurring while the nut is being advanced through the next360 of nut rotation shall be recorded. This torque shall not exc
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