SIST EN ISO 7720:2025
(Main)Fasteners - Prevailing torque hexagon nuts - High nuts (all metal) with slot(s) (ISO 7720:2025)
Fasteners - Prevailing torque hexagon nuts - High nuts (all metal) with slot(s) (ISO 7720:2025)
This document specifies the characteristics of prevailing torque (all metal) hexagon high nuts with slot(s), in steel and stainless steel, with metric coarse pitch thread M5 to M39, and with product grades A and B.
NOTE These nuts are designed with mmin as specified ISO 4032 and with an overall height h greater than in ISO 7042, in order to accommodate the prevailing torque feature with slot(s); this height h contributes to the nut resistance due to the number of engaged threads. hmin values have been calculated as a function of hmax together with a ratio hmax/D that progresses regularly with increasing diameter; therefore, the tolerance (hmax – hmin) does not follow the ISO code system for tolerances (IT system).
If in certain cases other specifications are requested, property classes and stainless steel grades can be selected from ISO 898-2 or ISO 3506-2.
Verbindungselemente - Sechskantmuttern mit Klemmteil - Hohe Muttern (Ganzmetallmuttern) mit Schlitz(en) (ISO 7720:2025)
Dieses Dokument legt die Eigenschaften von hohen Sechskantmuttern mit Klemmteil (Ganzmetallmuttern) mit Schlitz(en) aus Stahl und nichtrostendem Stahl mit metrischen Regelgewinden von M5 bis M39, und in Produktklassen A und B fest.
ANMERKUNG Diese Muttern sind mit mmin wie in ISO 4032 festgelegt und mit einer Gesamthöhe h mehr als in ISO 7042 gestaltet, um das Klemmteil mit Schlitz(en) aufzunehmen; diese Höhe h trägt aufgrund der Anzahl der eingeschraubten Gewinde zum Widerstand der Mutter bei. Die hmin-Werte wurden als Funktion von hmax zusammen mit einem Verhältnis hmax/D berechnet, das sich mit zunehmendem Durchmesser regelmäßig erhöht; daher entspricht die Toleranz (hmax − hmin) nicht dem ISO-Toleranzsystem (IT-System).
Falls in bestimmten Fällen andere Festlegungen benötigt werden, können Festigkeitsklassen und Stahlsorten nichtrostender Stähle ISO 898 2 oder ISO 3506 2 entnommen werden.
Fixations - Écrous hexagonaux autofreinés - Écrous hauts (tout métal) à fente(s) (ISO 7720:2025)
Le présent document spécifie les caractéristiques des écrous hauts hexagonaux autofreinés (tout métal) à fente(s), en acier et en acier inoxydable, à filetage métrique à pas gros M5 à M39, et de grades A et B.
NOTE Ces écrous sont conçus avec mmin tel que spécifié dans l’ISO 4032 et avec une hauteur totale h plus importante que dans l’ISO 7042, pour être adaptés au dispositif d’autofreinage avec fente(s); cette hauteur h contribue à la résistance de l’écrou grâce au nombre de filets en prise. Les valeurs de hmin ont été calculées en fonction de hmax et en prenant en compte un ratio hmax/D qui augmente régulièrement avec le diamètre; de ce fait, la tolérance (hmax – hmin) ne s’intègre pas dans le système de codification ISO pour les tolérances (IT system).
Si dans certains cas d’autres spécifications sont requises, les classes de qualité et les grades d’acier inoxydable peuvent être choisis dans l’ISO 898-2 ou l’ISO 3506-2.
Vezni elementi - Šestrobe zaščitne matice - Visoke matice (vse kovine) z režo(-ami) (ISO 7720:2025)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2025
Vezni elementi - Šestrobe zaščitne matice - Visoke matice (vse kovine) z režo(-
ami) (ISO 7720:2025)
Fasteners - Prevailing torque hexagon nuts - High nuts (all metal) with slot(s) (ISO
7720:2025)
Verbindungselemente - Sechskantmuttern mit Klemmteil - Hohe Muttern
(Ganzmetallmuttern) mit Schlitz(en) (ISO 7720:2025)
Fixations - Écrous hexagonaux autofreinés - Écrous hauts (tout métal) à fente(s) (ISO
7720:2025)
Ta slovenski standard je istoveten z: EN ISO 7720:2025
ICS:
21.060.20 Matice Nuts
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 7720
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2025
EUROPÄISCHE NORM
ICS 21.060.20
English Version
Fasteners - Prevailing torque hexagon nuts - High nuts (all
metal) with slot(s) (ISO 7720:2025)
Fixations - Écrous hexagonaux autofreinés - Écrous Verbindungselemente - Sechskantmuttern mit
hauts (tout métal) à fente(s) (ISO 7720:2025) Klemmteil - Hohe Muttern (Ganzmetallmuttern) mit
Schlitz(en) (ISO 7720:2025)
This European Standard was approved by CEN on 21 June 2025.
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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7720:2025 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 7720:2025) 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
BSI.
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 December 2025, and conflicting national standards
shall be withdrawn at the latest by December 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 7720:2025 has been approved by CEN as EN ISO 7720:2025 without any modification.
International
Standard
ISO 7720
Fourth edition
Fasteners — Prevailing torque
2025-06
hexagon nuts — High nuts (all
metal) with slot(s)
Fixations — Écrous hexagonaux autofreinés — Écrous hauts
(tout métal) à fente(s)
Reference number
ISO 7720:2025(en) © ISO 2025
ISO 7720:2025(en)
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 7720:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Dimensions . 2
5 Requirements and reference International Standards . 4
6 Marking and labelling . 5
6.1 Marking on product . .5
6.2 Labelling on package .5
7 Designation . 5
Bibliography . 6
iii
ISO 7720:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 2, Fasteners, Subcommittee SC 12, Fasteners
with metric internal thread, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 185, Fasteners, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 7720:2012) which has been technically
revised.
The main changes are as follows:
— the title and scope have been changed in order to address the nut height: high (instead of style 2); the
design principles of these nuts have been clarified in Scope (see Note);
— property classes have been deleted from title and scope: style, relevant property classes and related
quenching and tempering conditions for steel nuts have been specified in Clause 5 in accordance with
ISO 898-2; property class 9 has been replaced by property classes 8 and 10; see Table 3;
— stainless steel nuts have been added in accordance with ISO 3506-2;
— M7, M18, M22, M27, M33 and M39 have been added;
— d has been specified with two decimal places;
a,max
— d for M5 has been changed from s – IT16 to s – IT15 in order to have a larger bearing surface
w,min min min
area and thus less contact pressure;
— m has been added with values in accordance with style 1; m = 0,8 m has been specified in
min w,min min
accordance with ISO 4759-1;
— the overall (total) height of the nut, h and h , have been increased to accommodate the prevailing
max min
torque feature with slot(s);
— specifications for marking and labelling have been added as Clause 6.
iv
ISO 7720:2025(en)
Any feedback or questions on this document should be directed to the user's national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
International Standard ISO 7720:2025(en)
Fasteners — Prevailing torque hexagon nuts — High nuts (all
metal) with slot(s)
1 Scope
This document specifies the characteristics of prevailing torque (all metal) hexagon high nuts with slot(s), in
steel and stainless steel, with metric coarse pitch thread M5 to M39, and with product grades A and B.
NOTE These nuts are designed with m as specified ISO 4032 and with an overall height h greater than in
min
ISO 7042, in order to accommodate the prevailing torque feature with slot(s); this height h contributes to the nut
resistance due to the number of engaged threads. h values have been calculated as a function of h together
min max
with a ratio h /D that progresses regularly with increasing diameter; therefore, the tolerance (h – h ) does not
max max min
follow the ISO code system for tolerances (IT system).
If in certain cases other specifications are requested, property classes and stainless steel grades can be
selected from ISO 898-2 or ISO 3506-2.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 225, Fasteners — Bolts, screws, studs and nuts — Symbols and descriptions of dimensions
ISO 898-2, Fasteners — Mechanical properties of fasteners made of carbon steel and alloy steel — Part 2: Nuts
with specified property classes
ISO 965-1, ISO general purpose metric screw threads — Tolerances — Part 1: Principles and basic data
ISO 1891-4, Fasteners — Vocabulary — Part 4: Control, inspection, delivery, acceptance and quality
ISO 2320, Fasteners — Prevailing torque steel nuts — Functional properties
ISO 3269, Fasteners — Acceptance inspection
ISO 3506-2, Fasteners — Mechanical properties of corrosion-resistant stainless steel fasteners — Part 2: Nuts
with specified grades and property classes
ISO 4042, Fasteners — Electroplated coating systems
ISO 4759-1, Tol
...
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