GB/T 3098.9-2020Mechanical properties of fasteners - Prevailing torque type steel nuts (English PDF)

Foreword

GB/T 3098 "Mechanical properties of fasteners" includes the following parts.

- GB/T 3098.1 Mechanical properties of fasteners - Bolts, screws and studs;

- GB/T 3098.2 Mechanical properties of fasteners - Nuts;

- GB/T 3098.3 Mechanical properties of fasteners - Set screws;

- GB/T 3098.5 Mechanical properties of fasteners - Tapping screws;

- GB/T 3098.6 Mechanical properties of fasteners - Stainless steel bolts,

screws and studs;

- GB/T 3098.7 Mechanical properties of fasteners - Thread rolling screws;

- GB/T 3098.8 Mechanical properties of fasteners - Parts for bolted

connections for use at temperatures from -200 Celsius~+700 Celsius;

- GB/T 3098.9 Mechanical properties of fasteners - Prevailing torque type

steel nuts;

- GB/T 3098.10 Mechanical properties of fasteners - Bolts, screws, studs and

nuts made of non-ferrous metals;

- GB/T 3098.11 Mechanical properties of fasteners - Drilling screws with

tapping screw thread;

- GB/T 3098.12 Mechanical properties of fasteners - Cone proof load test on

nuts;

- GB/T 3098.13 Mechanical properties of fasteners - Torsional test and

minimum torques for bolts and screws with nominal diameters from 1 mm

to 10 mm;

- GB/T 3098.14 Mechanical properties of fasteners - Widening test on nuts;

- GB/T 3098.15 Mechanical properties of fasteners - Nuts made of stainless-

steel;

- GB/T 3098.16 Mechanical properties of fasteners - Stainless steel set

screws;

- GB/T 3098.17 Mechanical properties of fasteners - Preloading test for the

detection of hydrogen embrittlement - Parallel bearing surface method;

- GB/T 3098.18 Mechanical properties of fasteners - Blind rivets testing;

- GB/T 3098.19 Mechanical properties of fasteners - Blind rivets with break

pull mandrel;

- GB/T 3098.20 Mechanical properties of fasteners - Wing nuts with specified

proof torque;

- GB/T 3098.21 Mechanical properties of fasteners - Stainless steel tapping

screws;

- GB/T 3098.22 Mechanical properties of fasteners made of the fine grain

non-heat treatment steel - Bolts, screws and studs;

- GB/T 3098.23 Mechanical properties of fasteners - M42~M72 bolts, screws

and studs;

- GB/T 3098.24 Mechanical properties of fasteners - Stainless steel and

nickel alloy bolts, screws, studs and nuts for high temperature;

- GB/T 3098.25 Mechanical properties of fasteners - Guide for selection of

stainless steel and nickel alloy fasteners.

This Part is Part 9 of GB/T 3098.

This Part is drafted in accordance with the rules given in GB/T 1.1-2009.

This Part replaces GB/T 3098.9-2010 "Mechanical properties of fasteners -

Prevailing torque type steel nuts". Compared with GB/T 3098.9-2010, the main

technical changes of this Part are as follows.

- Delete nuts of class 9 (see Table 6 and Table 9 of the 2010 edition);

- GIVE the data of thread specifications M3 and M4 as an annex (see Annex

C);

- Surface condition of the test bolt/screw shall be in accordance with GB/T

1 Scope

This Part of GB/T 3098 specifies the functional properties for prevailing torque

steel nuts when tested at an ambient temperature of 10 °C to 35 °C. It includes

a combined test method to determine the prevailing torque properties and the

torque/clamp force properties at the same time.

2 Normative references

The following documents are indispensable for the application of this document.

For the dated references, only the editions with the dates indicated are

applicable to this document. For the undated references, the latest edition

(including all the amendments) are applicable to this document.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in GB/T

4 Symbols

For the purpose of this document, the following symbols apply together with

those defined in GB/T 16823.3.

5 Thread

Threads for the nuts shall be in accordance with GB/T 9145 except for the

prevailing torque feature.

6 Lubrication

At the option of the manufacturer, a lubricant may be applied to the

manufacturing lot to fulfil the functional requirements.

7 Mechanical properties of prevailing torque nuts

The mechanical properties of prevailing torque nuts shall conform to GB/T

3098.2.

8 Functional requirements for prevailing torque properties

The prevailing-on torque shall not exceed the value specified in Tables 1 to 7.

9 Test method

The proof load test shall be carried out in accordance with GB/T 3098.2.

Additionally, the following applies.

Annex A

(Normative)

Temperature influence on prevailing torques of nuts with non-metallic

insert

Annex B

(Informative)

Principles for the evaluation of the total coefficient of friction, µtot

In Figure B.1, the tightening process runs up to a test clamp force of 80 % of

the proof load of the mating bolt.

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