Fasteners - Hexagon weld nuts with flange (ISO 21670:2014)

ISO 21670:2014 specifies characteristics for hexagon weld nuts with flange, with sizes M5 to M16 (coarse thread) or d = 8 mm to 16 mm (fine pitch thread), of product grade A. Weld nuts conforming to ISO 21670:2014 are suitable for use with bolts of property classes up to 10.9 according to ISO 898‑1.

Mechanische Verbindungselemente - Sechskant-Schweißmuttern mit Flansch (ISO 21670:2014)

Diese Internationale Norm legt Eigenschaften von Sechskant-Schweißmuttern mit Flansch mit metrischem Regelgewinde von M5 bis M16 oder metrischem Feingewinde mit Gewinde-Nenndurchmesser D von 8 mm bis 16 mm in Produktklasse A fest.
Schweißmuttern nach dieser Norm sind zur Verschraubung mit Schrauben der Festigkeitsklassen bis einschließlich 10.9 nach ISO 898-1 geeignet.

Fixations - Écrous hexagonaux à souder, à embase plate (ISO 21670:2014)

L'ISO 21670:2014 spécifie les caractéristiques des écrous à souder, à embase, de diamètre de filetage M5 à M16 inclus (pas gros) et de M8 à M16 inclus (pas fin), et de grade A. Les écrous à souder conformes à L'ISO 21670:2014 sont appropriés pour être utilisés avec des vis de classe de qualité jusqu'à 10.9 inclus selon l'ISO 898-1.

Vezni elementi - Šestroba matica s krajcem za privarjenje (ISO 21670:2014)

EN ISO 21670 določa lastnosti šestrobih matic s krajcem za privarjenje velikosti M5 do M16 (grobi navoj) ali premera D = 8 mm do 16 mm (fini navoj) razreda izdelave A. Matice za privarjenje, ki so skladne s tem mednarodnim standardom, so primerne za uporabo z vijaki razredov trdnosti do 10.9 v skladu s standardom ISO 898-1.

General Information

Status
Published
Publication Date
20-May-2014
Withdrawal Date
29-Nov-2014
ICS
21.060.20 - Nuts
Technical Committee
CEN/TC 185 - Threaded and nonthreaded mechanical fasteners and accessories
Drafting Committee
CEN/TC 185 - Threaded and nonthreaded mechanical fasteners and accessories
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
21-May-2014
Due Date
09-Dec-2014
Completion Date
21-May-2014
Ref Project
SIST EN ISO 21670:2014 - Fasteners - Hexagon weld nuts with flange (ISO 21670:2014)

Relations

Replaces
EN ISO 21670:2003 - Hexagon weld nuts with flange (ISO 21670:2003)
Effective Date
28-May-2014
Refers
prEN 15011 - Cranes - Bridge and gantry cranes
Effective Date
28-Jan-2026
Refers
EN 1337-2:2004 - Structural bearings - Part 2: Sliding elements
Effective Date
28-Jan-2026
Refers
EN ISO 11127-2:1997 - Preparation of steel substrates before application of paints and related products - Test methods for non-metallic blast-cleaning abrasives - Part 2: Determination of particle size distribution (ISO 11127-2:1993)
Effective Date
28-Jan-2026
Referred By
EN 1090-2:2018+A1:2024 - Execution of steel structures and aluminium structures - Part 2: Technical requirements for steel structures
Effective Date
28-Jan-2026

Overview

EN ISO 21670:2014 (ISO 21670:2014) covers specifications for hexagon weld nuts with flange (weld nuts) of product grade A. It defines sizes, material limits, mechanical properties, tolerances, marking and inspection rules for weld nuts intended to be welded to components and used with bolts up to property class 10.9 (per ISO 898‑1). Typical thread sizes covered are M5 to M16 (coarse) and fine-pitch variants (D = 8 mm to 16 mm).

Key topics and technical requirements

  • Dimensions and connecting details: Nut geometry, flange and pressing contours, and recommended hole/plate thickness ranges are specified (see figures/tables in the standard).
  • Threads and tolerances: Threads follow ISO 724 with tolerance class 6G (ISO 965‑3). Product grade: A (ISO 4759‑1).
  • Material: Steel with a maximum carbon content of 0.25% and a maximum carbon equivalent (CEV) of 0.53% (CEV formula provided in the standard). Use of free‑cutting steels is prohibited. If quenched & tempered, hardness must not exceed 300 HV.
  • Mechanical properties / proof loads: Proof load values are specified per size (tested in accordance with ISO 898‑2). Welding projections should be removed before testing in disputes.
  • Surface finish & integrity: Nuts are delivered uncoated; manufacturers must ensure corrosion protection that does not impair weldability. Surface discontinuity limits are per ISO 6157‑2.
  • Acceptance inspection: Procedures follow ISO 3269.
  • Designation & marking: Standardized designation format (e.g., Weld nut ISO 21670 - M10 – St) and mandatory manufacturer mark on the face opposite the flange for sizes M5 and larger.

Applications and who uses this standard

  • Designed for manufacturers and suppliers of fasteners, specifically hexagon weld nuts with flange used in welded assemblies.
  • Relevant to industries that require welded nut attachments: automotive, heavy machinery, construction, metal fabrication and sheet‑metal assembly.
  • Useful to:
    • Design and mechanical engineers selecting weldable fastening solutions
    • Purchasing/procurement teams specifying compliant components
    • Quality/inspection personnel verifying acceptance criteria and proof load testing
    • Standards managers and product developers ensuring weldability and mechanical compatibility with bolts up to class 10.9

Related standards

Normative references in EN ISO 21670:2014 include:

  • ISO 724 (metric thread basic dimensions)
  • ISO 898‑1 / ISO 898‑2 (mechanical properties for bolts and nuts)
  • ISO 965‑3 (thread tolerances)
  • ISO 4759‑1 (tolerances - product grades)
  • ISO 6157‑2 (surface discontinuities - nuts)
  • ISO 3269 (acceptance inspection)
  • ISO 8992 (general fastener requirements)

Keywords: hexagon weld nuts with flange, EN ISO 21670:2014, ISO 21670, weld nuts, fasteners standard, product grade A, M5 to M16, bolt property class 10.9, proof load, tolerances 6G.

Frequently Asked Questions

EN ISO 21670:2014 is a standard published by the European Committee for Standardization (CEN). Its full title is "Fasteners - Hexagon weld nuts with flange (ISO 21670:2014)". This standard covers: ISO 21670:2014 specifies characteristics for hexagon weld nuts with flange, with sizes M5 to M16 (coarse thread) or d = 8 mm to 16 mm (fine pitch thread), of product grade A. Weld nuts conforming to ISO 21670:2014 are suitable for use with bolts of property classes up to 10.9 according to ISO 898‑1.

ISO 21670:2014 specifies characteristics for hexagon weld nuts with flange, with sizes M5 to M16 (coarse thread) or d = 8 mm to 16 mm (fine pitch thread), of product grade A. Weld nuts conforming to ISO 21670:2014 are suitable for use with bolts of property classes up to 10.9 according to ISO 898‑1.

EN ISO 21670:2014 is classified under the following ICS (International Classification for Standards) categories: 21.060.20 - Nuts. The ICS classification helps identify the subject area and facilitates finding related standards.

EN ISO 21670:2014 has the following relationships with other standards: It is inter standard links to EN ISO 21670:2003, prEN 15011, EN 1337-2:2004, EN ISO 11127-2:1997, EN 1090-2:2018+A1:2024. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

EN ISO 21670:2014 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

Standards Content (Sample)


SLOVENSKI STANDARD
01-julij-2014
1DGRPHãþD
SIST EN ISO 21670:2004
Vezni elementi - Šestroba matica s krajcem za privarjenje (ISO 21670:2014)
Fasteners - Hexagon weld nuts with flange (ISO 21670:2014)
Sechskant-Schweißmuttern mit Flansch (ISO 21670:2014)
Fixations - Écrous hexagonaux à souder, à embase plate (ISO 21670:2014)
Ta slovenski standard je istoveten z: EN ISO 21670:2014
ICS:
21.060.20 Matice Nuts
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 21670
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2014
ICS 21.060.20 Supersedes EN ISO 21670:2003
English Version
Fasteners - Hexagon weld nuts with flange (ISO 21670:2014)
Fixations - Écrous hexagonaux à souder, à embase plate Mechanische Verbindungselemente - Sechskant-
(ISO 21670:2014) Schweißmuttern mit Flansch (ISO 21670:2014)
This European Standard was approved by CEN on 13 April 2014.

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
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21670:2014 E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 21670:2014) 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 November 2014, and conflicting national standards shall be withdrawn
at the latest by November 2014.
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 21670:2003.
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 21670:2014 has been approved by CEN as EN ISO 21670:2014 without any modification.

INTERNATIONAL ISO
STANDARD 21670
Second edition
2014-05-15
Fasteners — Hexagon weld nuts with
flange
Fixations — Écrous hexagonaux à souder, à embase plate
Reference number
ISO 21670:2014(E)
©
ISO 2014
ISO 21670:2014(E)
© ISO 2014
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.
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Published in Switzerland
ii © ISO 2014 – All rights reserved

ISO 21670:2014(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Dimensions . 1
4 Technical delivery conditions . 3
4.1 General requirements . 3
4.2 Material . 3
4.3 Tolerances . 3
4.4 Mechanical properties . 3
4.5 Surface finish . 3
4.6 Surface integrity. 4
4.7 Acceptance inspection . 4
5 Designation . 4
6 Marking . 4
7 Connecting dimensions .
...

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