SIST EN ISO 2320:2016

SLOVENSKI STANDARD
SIST EN ISO 2320:2016
01-marec-2016
1DGRPHãþD
SIST EN ISO 2320:2009
Vezni elementi - Jeklene samovarovalne matice - Mehanske in funkcionalne
lastnosti (ISO 2320:2015)
Fasteners - Prevailing torque type steel nuts - Mechanical and performance properties
(ISO 2320:2015)
Mechanische Verbindungselemente - Muttern aus Stahl mit Klemmteil - Mechanische
und funktionelle Eigenschaften (ISO 2320:2015)
Fixations - Écrous autofreinés en acier - Caractéristiques mécaniques et performances
(ISO 2320:2015)
Ta slovenski standard je istoveten z: EN ISO 2320:2015
ICS:
21.060.20 Matice Nuts
SIST EN ISO 2320:2016 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 2320:2016

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SIST EN ISO 2320:2016


EN ISO 2320
EUROPEAN STANDARD

NORME EUROPÉENNE

December 2015
EUROPÄISCHE NORM
ICS 21.060.20 Supersedes EN ISO 2320:2008
English Version

Fasteners - Prevailing torque steel nuts - Functional
properties (ISO 2320:2015)
Fixations - Écrous autofreinés en acier - Mechanische Verbindungselemente - Muttern aus Stahl
Caractéristiques fonctionnelles (ISO 2320:2015) mit Klemmteil - Mechanische und funktionelle
Eigenschaften (ISO 2320:2015)
This European Standard was approved by CEN on 17 October 2015.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 2320:2015 E
worldwide for CEN national Members.

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SIST EN ISO 2320:2016
EN ISO 2320:2015 (E)
Contents Page
European foreword . 3
2

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SIST EN ISO 2320:2016
EN ISO 2320:2015 (E)
European foreword
This document (EN ISO 2320:2015) has been prepared by Technical Committee ISO/TC 2 "Fasteners" in
collaboration with Technical Committee CEN/TC 185 “Fasteners” the secretariat of which is held by
DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by June 2016, and conflicting national standards shall be
withdrawn at the latest by June 2016.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 2320:2008.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 2320:2015 has been approved by CEN as EN ISO 2320:2015 without any modification.


3

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SIST EN ISO 2320:2016

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SIST EN ISO 2320:2016
INTERNATIONAL ISO
STANDARD 2320
Fifth edition
2015-12-01
Fasteners — Prevailing torque steel
nuts — Functional properties
Fixations — Écrous autofreinés en acier — Caractéristiques
fonctionnelles
Reference number
ISO 2320:2015(E)
©
ISO 2015

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2015 – All rights reserved

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Thread . 3
6 Lubrication . 3
7 Mechanical properties of prevailing torque nuts . 3
8 Functional requirements for prevailing torque properties . 3
9 Test method .11
9.1 General .11
9.2 Proof load test .11
9.3 Prevailing torque test .11
9.3.1 General.11
9.3.2 Test apparatus .12
9.3.3 Test parts .12
9.3.4 Test procedure .13
9.3.5 Test report .15
Annex A (normative) Temperature influence on prevailing torques of nuts with non-
metallic insert .16
Annex B (informative) Principles for the evaluation of the total coefficient of friction, μ .17
tot
Annex C (informative) Test clamp force and prevailing torques for prevailing torque nuts
M3 and M4 in property classes 8 and 10 .18
Bibliography .20
© ISO 2015 – All rights reserved iii

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 2, Fasteners, Subcommittee SC 12, Fasteners
with metric internal thread.
This fifth edition cancels and replaces the fourth edition (ISO 2320:2008), which has been technically
revised. The following changes have been made:
— property class 9 has been deleted;
— prevailing torques for nuts M3 and M4 have been moved to Annex C;
— in the test fixture, the thread protrusion through the prevailing torque feature has been changed to
3 to 5 pitches;
— the reference surface condition for the test bolt has been specified in accordance with ISO 16047
(plain surface, uncoated and degreased, unless otherwise agreed);
— the determination of the prevailing-off torque has been changed from the upper value to the
minimum value (new point 5 in Figure 2), which changes the acceptance conditions;
— other editorial revisions.
iv © ISO 2015 – All rights reserved

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SIST EN ISO 2320:2016
INTERNATIONAL STANDARD ISO 2320:2015(E)
Fasteners — Prevailing torque steel nuts — Functional
properties
1 Scope
This International Standard specifies the functional properties for prevailing torque steel nuts when
tested at an ambient temperature range 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.
It applies to prevailing torque all metal type nuts and prevailing torque non-metallic insert type nuts:
— with triangular ISO thread in accordance with ISO 68-1;
— with diameter/pitch combination in accordance with ISO 261 and ISO 262;
— with coarse pitch thread M5 to M39 or with fine pitch thread M8 × 1 to M39 × 3;
— with thread tolerances in accordance with ISO 965-2;
— with mechanical properties in accordance with ISO 898-2;
Prevailing torque values specified in this standard are based on laboratory test conditions.
NOTE 1 Actual prevailing torques in practical application can vary.
NOTE 2 All metal type nuts conforming to the requirements of this International Standard are used in
applications ranging from −50 °C to +150 °C.
NOTE 3 Non-metallic insert type nuts conforming to the requirements of this International Standard are used
in applications ranging from −50 °C to +120 °C.
WARNING — Temperatures outside the ambient temperature range can influence the functional
properties (torque/clamp force and prevailing torque properties), see Annex A.
2 Normative references
The following referenced documents, in whole or in part, are normatively referenced in this document
and are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 273, Fasteners — Clearance holes for bolts and screws
ISO 898-1, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts, screws
and studs with specified property classes — Coarse thread and fine pitch thread
ISO 898-2, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 2: Nuts with
specified property classes — Coarse thread and fine pitch thread
ISO 965-2, ISO general purpose metric screw threads — Tolerances — Part 2: Limits of sizes for general
purpose external and internal screw threads — Medium quality
ISO 16047:2005, Fasteners — Torque/clamp force testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16047 and the following apply.
© ISO 2015 – All rights reserved 1

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

3.1
prevailing torque nut
nut which is not free-running on a mating thread by virtue of a self-contained prevailing torque feature,
and which provides resistance to rotation independent of clamping or compression forces
3.2
prevailing torque developed by the nut
torque necessary to rotate the nut on its mating externally threaded component and without clamp force
3.3
prevailing-on torque
torque to rotate the nut on its mating externally threaded component with the torque measured while
the nut is in motion and without clamp force
3.4
prevailing-off torque
torque to rotate after backing off the nut until the removal of the clamp force in the following 360°
rotation of the nut
3.5
prevailing torque all metal type nut
nut which has a one piece or a multiple piece metal construction and derives its prevailing torque
characteristics from a controlled distortion of the nut thread and/or body and/or from metallic insert(s)
3.6
prevailing torque non-metallic insert type nut
nut which has a multiple piece construction and derives its prevailing torque characteristics from
insert(s) of non-metallic material retained in the nut
3.7
seating point
point in the tightening process where clamp force first appears
4 Symbols
For the purpose of this International Standard, the following symbols apply together with those defined
in ISO 16047.
D nominal diameter, in millimetre
d diameter of the hole of the fixture, in millimetre
4
F proof load, in newton
P
F lower load limit for the evaluation of the coefficient of total friction at 65 % of F , in newton
65 P
F upper load limit for the evaluation of the coefficient of total friction at 75 % of F , in newton
75 P
F test clamp force (shut-down force for the tightening process) at 80 % of F , in newton
80 P
P pitch of the thread, in millimetre
T prevailing-on torque, in newton metre
Fv
T prevailing-off torque, in newton metre
Fd
T lower torque limit for the evaluation of the coefficient of total friction at F , in newton metre
65 65
T upper torque limit for the evaluation of the coefficient of total friction at F , in newton metre
75 75
2 © ISO 2015 – All rights reserved

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

T test torque corresponding to 80 % of the proof load, in newton metre (see Tables 1 to 7)
80
μ coefficient of total friction
tot
5 Thread
Threads for prevailing torque nuts shall be in accordance with ISO 965-2 except for the prevailing
torque feature:
a) for prevailing torque non-metallic insert type nuts, the GO gauge shall be suitable for free
installation (by hand) until it is seated against the prevailing torque feature;
b) for prevailing torque all metal type nuts, the GO gauge shall be suitable for free installation (by
hand) to one pitch at least.
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 ISO 898-2.
With regard to proof load, the test method specified in 9.2 shall apply.
8 Functional requirements for prevailing torque properties
The prevailing-on torque shall not exceed the value specified for the applicable nut in Tables 1 to 7.
The prevailing-off torque shall exceed the value specified for the applicable nut in Tables 1 to 7.
For delivery inspection, the first installation/removal test applies, unless otherwise agreed.
th
For initial type testing and in case of dispute, a 5 removal test shall also be applied unless
otherwise agreed.
Prevailing torque performance decreases as a function of the number of reuses; the consumer shall
take into consideration the consequences of the decreased performance before any reuse of the nut.
By request of the customer, a temperature influence test for prevailing torque non-metallic insert type
nuts as specified in Annex A may be carried out.
© ISO 2015 – All rights reserved 3

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

Table 1 — Test clamp force and prevailing torques for prevailing torque nuts of property class 04
Clamp force for evaluation
Prevailing torque
of total friction coefficient
Nm
Thread b
µ
tot
Test clamp
D
force Upper limit Lower limit
D×P
st st th
1 installation 1 removal 5 removal
a c d
F F F
80 75 65
e
T T T
Fv,max Fd,min Fd,min
N N N
M5 4 320 4 050 3 510 1,6 0,29 0,2
M6 6 112 5 730 4 966 3 0,45 0,3
M7 8 800 8 250 7 150 4,5 0,65 0,45
M8 11 120 10 425 9 035
6 0,85 0,6
M8×1 11 920 11 175 9 685
M10 17 600 16 500 14 300
M10×1,25 18 640 17 475 15 145 10,5 1,5 1
M10×1 19 600 18 375 15 925
M12 25 600 24 000 20 800
M12×1,5 26 800 25 125 21 775 15,5 2,3 1,6
M12×1,25 28 000 26 250 22 750
M14 34 960 32 775 28 405
24 3,3 2,3
M14×1,5 38 000 35 625 30 875
M16 47 760 44 775 38 805
32 4,5 3
M16×1,5 50 800 47 625 41 275
M18 58 400 54 750 47 450
42 6 4,2
M18×1,5 65 360 61 275 53 105
M20 74 480 69 825 60 515
54 7,5 5,3
M20×1,5 82 720 77 550 67 210
M22 92 080 86 325 74 815
68 9,5 6,5
M22×1,5 101 200 94 875 82 225
M24 107 280 100 575 87 165
80 11,5 8
M24×2 116 720 109 425 94 835
M27 139 520 130 800 113 360
94 13,5 10
M27×2 150 800 141 375 122 525
M30 170 560 159 900 138 580
108 16 12
M30×2 188 800 177 000 153 400
M33 210 960 197 775 171 405
122 18 14
M33×2 231 360 216 900 187 980
M36 248 400 232 875 201 825
136 21 16
M36×3 262 960 246 525 213 655
M39 296 720 278 175 241 085
150 23 18
M39×3 313 120 293 550 254 410
NOTE The evaluation of results from the prevailing torque test by statistical process control methods (SPC) has no
statistical relevance.
a
The clamp force for property class 04 nuts is equal to 80 % of the proof load of property class 04 specified in ISO 898-2
for nuts with 5 mm ≤ D ≤ 39 mm.
b
See Annex B.
c
The value of the upper limit of the clamp force is equal to 75 % of the proof load, see Annex B.
d
The value of the lower limit of the clamp force is equal to 65 % of the proof load, see Annex B.
e
The values of prevailing torque for first assembly apply for all metal type nuts only. For prevailing torque non-metallic
insert type nuts, the maximum prevailing torques shall be 50 % of the values.
4 © ISO 2015 – All rights reserved

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

Table 2 — Test clamp force and prevailing torques for prevailing torque nuts of property class 05
Clamp force for evaluation
Prevailing torque
of total friction coefficient
Test clamp
Nm
Thread b
µ
tot
force
D
a
F
80
Upper limit Lower limit
D×P
st st th
1 installation 1 removal 5 removal
N
c d
F F
75 65
e
T T T
Fv,max Fd,min Fd,min
N N
M5 5 680 5 325 4 615 2,1 0,35 0,24
M6 8 000 7 500 6 500 4 0,55 0,4
M7 11 600 10 875 9 425 6 0,85 0,6
M8 14 640 13 725 11 895
8 1,15 0,8
M8×1 15 680 14 700 12 740
M10 23 200 21 750 18 850
M10×1,25 24 480 22 950 19 890 14 2 1,4
M10×1 25 760 24 150 20 930
M12 33 760 31 650 27 430
M12×1,5 35 200 33 000 28 600 21 3,1 2,1
M12×1,25 36 800 34 500 29 900
M14 46 000 43 125 37 375
31 4,4 3
M14×1,5 50 000 46 875 40 625
M16 62 800 58 875 51 025
42 6 4,2
M16×1,5 66 800 62 625 54 275
M18 76 800 72 000 62 400
56 8 5,5
M18×1,5 86 000 80 625 69 875
M20 98 000 91 875 79 625
72 10,5 7
M20×1,5 108 800 102 000 88 400
M22 121 200 113 625 98 475
90 13 9
M22×1,5 133 200 124 875 108 225
M24 141 200 132 375 114 725
106 15 10,5
M24×2 153 600 144 000 124 800
M27 183 600 172 125 149 175
123 17 12
M27×2 198 400 186 000 161 200
M30 224 400 210 375 182 325
140 19 14
M30×2 248 400 232 875 201 825
M33 277 600 260 250 225 550
160 21,5 15,5
M33×2 304 400 285 375 247 325
M36 326 800 306 375 265 525
180 24 17,5
M36×3 346 000 324 375 281 125
M39 390 400 366 000 317 200
200 26,5 19,5
M39×3 412 000 386 250 334 750
NOTE The evaluation of results from the prevailing torque test by statistical process control methods (SPC) has no
statistical relevance.
a
The clamp force for property class 05 nuts is equal to 80 % of the proof load of property class 05 specified in ISO 898-2
for nuts with 5 mm ≤ D ≤ 39 mm.
b
See Annex B.
c
The value of the upper limit of the clamp force is equal to 75 % of the proof load, see Annex B.
d
The value of the lower limit of the clamp force is equal to 65 % of the proof load, see Annex B.
e
The values of prevailing torque for first assembly apply for all metal type nuts only. For prevailing torque non-metallic
insert type nuts, the maximum prevailing torques shall be 50 % of the values.
© ISO 2015 – All rights reserved 5

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

Table 3 — Test clamp force and prevailing torques for prevailing torque nuts of property class 5
Clamp force for evaluation
Prevailing torque
of total friction coefficient
Test clamp
Nm
Thread b
µ
tot
force
D
a
F
80
Upper limit Lower limit
D×P
st st th
1 installation 1 removal 5 removal
N
c d
F F
75 65
e
T T T
Fv,max Fd,min Fd,min
N N
M5 4 320 4 050 3 510 1,6 0,29 0,2
M6 6 112 5 730 4 966 3 0,45 0,3
M7 8 800 8 250 7 150 4,5 0,65 0,45
M8 11 120 10 425 9 035
6 0,85 0,6
M8×1 11 920 11 175 9 685
M10 17 600 16 500 14 300
M10×1,25 18 640 17 475 15 145 10,5 1,5 1
M10×1 19 600 18 375 15 925
M12 25 600 24 000 20 800
M12×1,5 26 800 25 125 21 775 15,5 2,3 1,6
M12×1,25 28 000 26 250 22 750
M14 34 960 32 775 28 405
24 3,3 2,3
M14×1,5 38 000 35 625 30 875
M16 47 760 44 775 38 805
32 4,5 3
M16×1,5 50 800 47 625 41 275
M18 58 400 54 750 47 450
42 6 4,2
M18×1,5 65 680 61 575 53 365
M20 74 480 69 825 60 515
54 7,5 5,3
M20×1,5 82 400 77 250 66 950
M22 92 000 86 250 74 750
68 9,5 6,5
M22×1,5 100 800 94 500 81 900
M24 107 200 100 500 87 100
80 11,5 8
M24×2 116 800 109 500 94 900
M27 113 600 106 500 92 300
94 13,5 10
M27×2 123 200 115 500 100 100
M30 139 200 130 500 113 100
108 16 12
M30×2 153 600 144 000 124 800
M33 172 000 161 250 139 750
122 18 14
M33×2 188 800 177 000 153 400
M36 202 400 189 750 164 450
136 21 16
M36×3 214 400 201 000 174 200
M39 242 400 227 250 196 950
150 23 18
M39×3 255 200 239 250 207 350
NOTE The evaluation of results from the prevailing torque test by statistical process control methods (SPC) has no
statistical relevance.
a
The clamp force for property class 5 nuts is equal to 80 % of the proof load of property class 5.8 specified in ISO 898-1
for bolts
b
See Annex B.
c
The value of the upper limit of the clamp force is equal to 75 % of the proof load, see Annex B.
d
The value of the lower limit of the clamp force is equal to 65 % of the proof load, see Annex B.
e
The values of prevailing torque for first assembly apply for all metal type nuts only. For prevailing torque non-metallic
insert type nuts, the maximum prevailing torques shall be 50 % of the values.
6 © ISO 2015 – All rights reserved

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

Table 4 — Test clamp force and prevailing torques for prevailing torque nuts of property class 6
Clamp force for evaluation
Prevailing torque
of total friction coefficient
Nm
Thread Test clamp force b
µ
tot
a
D F
80
Upper limit Lower limit
D×P N
st st th
1 installation 1 removal 5 removal
c d
F F
75 65
e
T T T
Fv,max Fd,min Fd,min
N N
M5 5 000 4 688 4 063 1,6 0,29 0,2
M6 7 072 6 630 5 746 3 0,45 0,3
M7 10 160 9 525 8 255 4,5 0,65 0,45
M8 12 880 12 075 10 465
6 0,85 0,6
M8×1 13 760 12 900 11 180
M10 20 400 19 125 16 575
M10×1,25 21 520 20 175 17 485 10,5 1,5 1
M10×1 22 720 21 300 18 460
M12 29 680 27 825 24 115
M12×1,5 31 040 29 100 25 220 15,5 2,3 1,6
M12×1,25 32 400 30 375 26 325
M14 40 480 37 950 32 890
24 3,3 2,3
M14×1,5 44 000 41 250 35 750
M16 55 280 51 825 44 915
32 4,5 3
M16×1,5 58 800 55 125 47 775
M18 67 600 63 375 54 925
42 6 4,2
M18×1,5 76 000 71 250 61 750
M20 86 400 81 000 70 200
54 7,5 5,3
M20×1,5 96 000 90 000 78 000
M22 106 400 99 750 86 450
68 9,5 6,5
M22×1,5 116 800 109 500 94 900
M24 124 000 116 250 100 750
80 11,5 8
M24×2 135 200 126 750 109 850
M27 161 600 151 500 131 300
94 13,5 10
M27×2 174 400 163 500 141 700
M30 197 600 185 250 160 550
108 16 12
M30×2 218 400 204 750 177 450
M33 244 000 228 750 198 250
122 18 14
M33×2 268 000 251 250 217 750
M36 287 200 269 250 233 350
136 21 16
M36×3 304 800 285 750 247 650
M39 343 200 321 750 278 850
150 23 18
M39×3 362 400 339 750 294 450
NOTE The evaluation of results from the prevailing torque test by statistical process control methods (SPC) has no
statistical relevance.
a
The clamp force for property class 6 nuts is equal to 80 % of the proof load of property class 6.8 specified in ISO 898-1
for bolts.
b
See Annex B.
c
The value of the upper limit of the clamp force is equal to 75 % of the proof load, see Annex B.
d
The value of the lower limit of the clamp force is equal to 65 % of the proof load, see Annex B.
e
The values of prevailing torque for first assembly apply for all metal type nuts only. For prevailing torque non-metallic
insert type nuts, the maximum prevailing torques shall be 50 % of the values.
© ISO 2015 – All rights reserved 7

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SIST EN ISO 2320:2016
ISO 2320:2015(E)

Table 5 — Test clamp force and prevailing torques for prevailing torque nuts of property class 8
Clamp force for evaluation
Prevailing torque
of total friction coefficient
Nm
Thread Test clamp force b
µ
tot
a
D F
80
Upper limit Lower limit
D×P N
st st th
1 installation 1 removal 5 removal
c d
F F
75 65
e
T T T
Fv,max Fd,min Fd,min
N N
M5 6 584 6 173 5 350 1,6 0,29 0,2
M6 9 280 8 700 7 540 3 0,45 0,3
M7 13 440 12 600 10 920 4,5 0,65 0,45
M8 16 960 15 900 13 780
6 0,85 0,6
M8×1 18 160 17 025 14 755
M10 26 960 25 275 21 905
M10×1,25 28 400 26 625 23 075 10,5 1,5 1
M10×1 29 920 28 050 24 310
M12 39 120
...