EN 3431:2007
(Main)Aerospace series - Nuts, hexagonal, self-locking, with counterbore and captive washer, in heat resisting steel, silver plated - Classification: 1 100 MPa (at ambient temperature) / 425 °C
Aerospace series - Nuts, hexagonal, self-locking, with counterbore and captive washer, in heat resisting steel, silver plated - Classification: 1 100 MPa (at ambient temperature) / 425 °C
This standard specifies the characteristics of self-locking hexagonal nuts, with counterbore and captive washer, in heat resisting steel, silver plated.
Classification: 1 100 MPa ) / 425 °C ).
Luft- und Raumfahrt - Sechskantmuttern, selbstsichernd, mit zylindrischer Aussenkung und Bördelscheibe, aus hochwarmfestem Stahl, versilbert - Klasse: 1 100 MPa (bei Raumtemperatur) / 425 °C
Diese Norm legt die Eigenschaften von selbstsichernden Sechskantmuttern mit zylindrischer Aussenkung und Bördelscheibe, aus hochwarmfestem Stahl, versilbert, fest.
Klasse: 1 100 MPa )/425 °C )
Série aérospatiale - Écrous hexagonaux, à freinage interne, avec chambrage et rondelle captive, en acier résistant à chaud, argentés - Classification : 1 100 MPa (à température ambiante) / 425 °C
Aeronavtika - Matice, šestrobe, samozapiralne, z ugreznjeno in robljeno podložko, iz toplotnoodpornega jekla, posrebrene - Klasifikacija: 1 100 MPa (pri temperaturi okolice) / 425 °C
General Information
- Status
- Published
- Publication Date
- 11-Dec-2007
- Withdrawal Date
- 29-Jun-2008
- Technical Committee
- ASD-STAN - Aerospace
- Drafting Committee
- ASD-STAN/D 3 - Mechanical
- Current Stage
- 9093 - Decision to confirm - Review Enquiry
- Start Date
- 30-Jun-2017
- Completion Date
- 11-Feb-2026
Relations
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Refers
EN 13001-1:2004/AC:2006 - Cranes - General design - Part 1: General principles and requirements - Effective Date
- 28-Jan-2026
- Effective Date
- 28-Jan-2026
- Effective Date
- 22-May-2024
Overview
EN 3431:2007 is a European Standard developed by CEN for the aerospace industry. It specifies the characteristics of hexagonal, self-locking nuts with counterbore and captive washer, produced from heat resisting steel and finished with a silver plating. These nuts are classified to withstand tensile stresses up to 1,100 MPa (at ambient temperature) and operate reliably at temperatures up to 425°C. This standard is part of the broader aerospace fastener specifications and supports consistency, safety, and performance within critical aerospace applications.
Key Topics
Main features covered by EN 3431:2007 include:
Design and Configuration
- Hexagonal shape for efficient torque transmission
- Self-locking mechanism to prevent loosening under vibration
- Counterbore and captive washer ensure secure assembly and spreading of load
Material and Surface Treatment
- Manufactured from heat resisting steel suitable for high-temperature environments
- Silver plated surface, enhancing corrosion resistance and reducing galling
Mechanical Performance
- Tensile strength classification: 1,100 MPa (at ambient temperature)
- Maximum service temperature: 425°C
Dimensional and Tolerance Requirements
- Follows ISO 8538 and ISO 5855-2 for precise threading and sizing
- Tolerances of form and position compliant with ISO 8788
Markings and Traceability
- Permanent identification in accordance with EN 2424 for aerospace products
Applications
These hexagonal, self-locking nuts are designed specifically for aerospace applications where performance under elevated temperatures and vibration is crucial. Typical usage scenarios include:
Aircraft Engines and Components:
Used in environments exposed to high temperatures, such as engine mounts, exhaust systems, and turbine assemblies.Structural Assemblies:
Applied in primary and secondary structures where mechanical vibration and temperature resistance are paramount.Aerospace Equipment:
Suitable for fastening critical systems in satellites, space vehicles, and high-performance military or commercial aircraft.
The combination of self-locking design, high mechanical strength, and silver plating ensures both secure fastening and resistance to environmental challenges specific to the aerospace sector.
Related Standards
EN 3431:2007 references and aligns with several other key international and European standards for aerospace fasteners:
- ISO 5855-2: Aerospace - MJ threads - Part 2: Limit dimensions for bolts and nuts
- ISO 5858: Aerospace - Nuts, self-locking, with maximum operating temperature ≤ 425°C - Procurement specification
- ISO 8538: Aerospace - Nuts, hexagonal, self-locking, with counterbore and captive washer, with MJ threads
- ISO 8788: Aerospace - Nuts, metric - Tolerances of form and position
- EN 2424: Marking of aerospace products
- EN 2516: Passivation of corrosion resisting steels and decontamination of nickel base alloys
- EN 2786: Electrolytic silver plating of fasteners
- EN 9100: Aerospace series - Quality management systems (based on ISO 9001)
- EN 9133: Qualification procedure for aerospace standard parts
Implementing EN 3431:2007 helps manufacturers, suppliers, and maintenance organizations ensure compatibility, safety, and reliability in aerospace applications, while facilitating international trade through harmonized technical requirements.
Keywords: EN 3431:2007, aerospace hex nuts, self-locking nuts, captive washer, heat resisting steel, silver plated fasteners, high temperature fasteners, aerospace standards, CEN, aircraft components, fastener specifications.
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Frequently Asked Questions
EN 3431:2007 is a standard published by the European Committee for Standardization (CEN). Its full title is "Aerospace series - Nuts, hexagonal, self-locking, with counterbore and captive washer, in heat resisting steel, silver plated - Classification: 1 100 MPa (at ambient temperature) / 425 °C". This standard covers: This standard specifies the characteristics of self-locking hexagonal nuts, with counterbore and captive washer, in heat resisting steel, silver plated. Classification: 1 100 MPa ) / 425 °C ).
This standard specifies the characteristics of self-locking hexagonal nuts, with counterbore and captive washer, in heat resisting steel, silver plated. Classification: 1 100 MPa ) / 425 °C ).
EN 3431:2007 is classified under the following ICS (International Classification for Standards) categories: 49.030.30 - Nuts. The ICS classification helps identify the subject area and facilitates finding related standards.
EN 3431:2007 has the following relationships with other standards: It is inter standard links to EN 2786:2008, EN 840-6:2004+A1:2008, EN 9100:2018, EN 2516:2023, EN 2424:2008, EN 9133:2018, EN 13001-1:2004/AC:2006, EN ISO 15792-1:2008, EN 3531:2025. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN 3431:2007 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)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aerospace series - Nuts, hexagonal, self-locking, with counterbore and captive washer, in heat resisting steel, silver plated - Classification: 1 100 MPa (at ambient temperature) / 425 °CAeronavtika - Matice, šestrobe, samozapiralne, z ugreznjeno in robljeno podložko, iz toplotnoodpornega jekla, posrebrene - Klasifikacija: 1 100 MPa (pri temperaturi okolice) / 425 °CSérie aérospatiale - Écrous hexagonaux, à freinage interne, avec chambrage et rondelle captive, en acier résistant à chaud, argentés - Classification : 1 100 MPa (à température ambiante) / 425 °CLuft- und Raumfahrt - Sechskantmuttern, selbstsichernd, mit zylindrischer Aussenkung und Bördelscheibe, aus hochwarmfestem Stahl, versilbert - Klasse: 1 100 MPa (bei Raumtemperatur) / 425 °CTa slovenski standard je istoveten z:EN 3431:2007SIST EN 3431:2008en49.030.30ICS:SLOVENSKI
STANDARDSIST EN 3431:200801-marec-2008
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 3431
December 2007 ICS 49.030.30 English Version
Aerospace series - Nuts, hexagonal, self-locking, with counterbore and captive washer, in heat resisting steel, silver plated - Classification: 1 100 MPa (at ambient temperature) / 425 °C
Série aérospatiale - Écrous hexagonaux, à freinage interne, avec chambrage et rondelle captive, en acier résistant à chaud, argentés - Classification : 1 100 MPa (à température ambiante) / 425 °C
Luft- und Raumfahrt - Sechskantmuttern, selbstsichernd, mit zylindrischer Aussenkung und Bördelscheibe, aus hochwarmfestem Stahl, versilbert - Klasse: 1 100 MPa (bei Raumtemperatur) / 425 °C This European Standard was approved by CEN on 5 November 2007.
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 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 Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
B-1050 Brussels © 2007 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 3431:2007: E
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