Aerospace series - Nuts, bihexagonal, self-locking, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), MoS2 coated - Classification: 1 550 MPa (at ambient temperature) / 425 °C

This document specifies the characteristics of self-locking bihexagonal nuts in NI-PH2601, MoS2 coated, for aerospace applications.
Classification: 1 550 MPa /425 °C .

Luft- und Raumfahrt - Zwölfkantmutter, selbstsichernd, aus hochwarmfester Nickelbasislegierung NI-PH2601 (Inconel 718), MoS2-beschichtet - Klasse: 1 550 MPa (bei Raumtemperatur) / 425 °C

Série aérospatiale - Écrou bihexagonaux, à freinage interne, en alliage résistant à chaud à base de nickel NI-PH2601 (Inconel 718), revêtus MoS2 - Classification : 1 550 MPa (à température ambiante ) / 425 °C

Le présent document spécifie les caractéristiques des écrous bihexagonaux, à freinage interne, en NI PH2601, revêtus au MoS2, pour les applications aérospatiales.
Classification : 1 550 MPa /425 °C.

Aeronavtika - Zakovne matice, biheksagonalne, samozaporne, iz toplotnoodporne zlitine na nikljevi osnovi NI-PH2601 (Inconel 718), mazane z MoS2 - Klasifikacija: 1 550 MPa (pri temperaturi okolice)/425 °C

General Information

Status
Published
Public Enquiry End Date
19-Sep-2023
Publication Date
16-Nov-2025
ICS
49.030.30 - Nuts
Technical Committee
I13 - Imaginarni 13
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
10-Nov-2025
Due Date
15-Jan-2026
Completion Date
17-Nov-2025
Ref Project
EN 4012:2025 - Aerospace series - Nut, bihexagonal, self-locking, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), MoS2 coated - Classification: 1 550 MPa (at ambient temperature)/425 °C

Relations

Replaces
SIST EN 4012:2005 - Aerospace series - Nuts, bihexagonal, self-locking, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), MoS2 coated - Classification: 1 550 MPa (at ambient temperature) / 425 °C
Effective Date
01-Jan-2026

Overview

SIST EN 4012:2026 is a European standard published by CEN that specifies the requirements for self-locking bihexagonal nuts made from the heat-resistant nickel base alloy NI-PH2601, commonly known as Inconel 718. These nuts are coated with molybdenum disulphide (MoS2) for lubrication and enhanced performance. This aerospace series standard addresses nuts classified to withstand tensile stresses of 1,550 MPa at ambient temperature and maintain integrity up to 425 °C. The standard replaces the previous EN 4012:2004 edition and includes updated technical and quality requirements.

Key Topics

  • Material Specification: Nuts must be manufactured from NI-PH2601 (Inconel 718), a nickel-chromium alloy known for excellent mechanical strength and heat resistance, as specified in EN 2952.
  • Dimensions and Tolerances: The nuts conform to precise bihexagonal configurations, dimensions, mass, and tolerances aligned with ISO 4095 and ISO 5855-2 to ensure interchangeability and optimum fit.
  • Surface Treatment: The MoS2 dry lubricant coating follows EN 2491, while surface passivation adheres to EN 2516 (types C2, C8, or C9) to enhance corrosion resistance without compromising mechanical properties.
  • Self-locking Design: The nuts feature an out-of-round deformation zone enabling self-locking performance, reducing the need for additional locking elements in aerospace fastenings.
  • Marking and Traceability: Marking requirements comply with EN 2424 style A, ensuring clarity for identification, quality control, and regulatory compliance.
  • Quality Management: Manufacturers must operate within approved aerospace production systems, certified under standards like EN 9100, guaranteeing consistent product quality and adherence to rigorous aerospace industry demands.
  • Testing and Qualification: The standard mandates documented qualification procedures based on EN 9133 or equivalent aerospace qualification protocols, ensuring that each production series meets aerospace safety and functional requirements.

Applications

SIST EN 4012:2026 nuts are designed specifically for aerospace applications where components must withstand high mechanical loads and elevated temperatures without failure. Typical uses include:

  • Aircraft structural assemblies requiring high-strength fasteners that endure thermal cycling.
  • Engine and exhaust component fastening where temperature resistance is critical.
  • Aerospace systems that demand reliable self-locking nuts to maintain preload under vibration and thermal expansion.
  • Replacement and maintenance parts conforming to international aerospace quality and safety standards.

The MoS2 coating reduces friction during assembly and enhances wear resistance, which is vital for aerospace fastener performance and longevity. The self-locking feature ensures secure fastening, increasing safety and reducing maintenance frequency.

Related Standards

To fully comply with aerospace quality requirements, EN 4012 references several other key standards:

  • EN 2952 - Defines the heat resistant nickel alloy NI-PH2601 for forged fasteners.
  • EN 2491 - Specifies molybdenum disulphide dry lubricant coating methods.
  • EN 2516 - Covers passivation processes for nickel and cobalt base alloys.
  • EN 4048 - Details technical specifications for nuts in similar alloys and coatings.
  • EN 2424 - Addresses marking requirements for aerospace products.
  • ISO 4095 - Establishes wrenching configuration for bihexagonal drives.
  • ISO 5855-2 - Defines thread limit dimensions for aerospace bolts and nuts.
  • EN 9100 - Aerospace quality management system requirements.
  • EN 9133 - Qualification procedures for aerospace standard products.

Utilizing nuts compliant with SIST EN 4012:2026 ensures certification-ready components that align with industry best practices for safety, performance, and reliability in aerospace manufacturing and maintenance sectors.

Keywords: EN 4012, aerospace nuts, self-locking nut, bihexagonal nuts, Inconel 718, NI-PH2601, MoS2 coating, heat resistant alloy, aerospace fasteners, nickel base alloy, tensile classification 1550 MPa, elevated temperature fasteners, aerospace quality management, EN 9100, aerospace standards, CEN fasteners

Frequently Asked Questions

SIST EN 4012:2026 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Aerospace series - Nuts, bihexagonal, self-locking, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), MoS2 coated - Classification: 1 550 MPa (at ambient temperature) / 425 °C". This standard covers: This document specifies the characteristics of self-locking bihexagonal nuts in NI-PH2601, MoS2 coated, for aerospace applications. Classification: 1 550 MPa /425 °C .

This document specifies the characteristics of self-locking bihexagonal nuts in NI-PH2601, MoS2 coated, for aerospace applications. Classification: 1 550 MPa /425 °C .

SIST EN 4012:2026 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.

SIST EN 4012:2026 has the following relationships with other standards: It is inter standard links to SIST EN 4012:2005. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

You can purchase SIST EN 4012:2026 directly from iTeh Standards. The document is available in PDF format and is delivered instantly after payment. Add the standard to your cart and complete the secure checkout process. iTeh Standards is an authorized distributor of SIST standards.

Standards Content (Sample)


SLOVENSKI STANDARD
01-januar-2026
Nadomešča:
SIST EN 4012:2005
Aeronavtika - Zakovne matice, biheksagonalne, samozaporne, iz toplotnoodporne
zlitine na nikljevi osnovi NI-PH2601 (Inconel 718), mazane z MoS2 - Klasifikacija: 1
550 MPa (pri temperaturi okolice)/425 °C
Aerospace series - Nuts, bihexagonal, self-locking, in heat resisting nickel base alloy NI-
PH2601 (Inconel 718), MoS2 coated - Classification: 1 550 MPa (at ambient
temperature) / 425 °C
Luft- und Raumfahrt - Zwölfkantmutter, selbstsichernd, aus hochwarmfester
Nickelbasislegierung NI-PH2601 (Inconel 718), MoS2-beschichtet - Klasse: 1 550 MPa
(bei Raumtemperatur) / 425 °C
Série aérospatiale - Écrou bihexagonaux, à freinage interne, en alliage résistant à chaud
à base de nickel NI-PH2601 (Inconel 718), revêtus MoS2 - Classification : 1 550 MPa (à
température ambiante ) / 425 °C
Ta slovenski standard je istoveten z: EN 4012:2025
ICS:
49.030.30 Matice Nuts
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 4012
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2025
EUROPÄISCHE NORM
ICS 49.030.30 Supersedes EN 4012:2004
English Version
Aerospace series - Nut, bihexagonal, self-locking, in heat
resisting nickel base alloy NI-PH2601 (Inconel 718), MoS2
coated - Classification: 1 550 MPa (at ambient
temperature)/425 °C
Série aérospatiale - Écrou bihexagonal, à freinage Luft- und Raumfahrt - Zwölfkantmutter,
interne, en alliage résistant à chaud base nickel NI- selbstsichernd, aus hochwarmfester
PH2601 (Inconel 718), revêtu MoS2 - Classification : 1 Nickelbasislegierung NI-PH2601 (Inconel 718), MoS2-
550 MPa (à température ambiante)/425 °C beschichtet - Klasse: 1 550 MPa (bei
Umgebungstemperatur)/425 °C
This European Standard was approved by CEN on 25 August 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 4012:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Required characteristics . 4
4.1 Configuration – Dimensions – Tolerances – Masses . 4
4.2 Material . 4
4.3 Surface treatment . 5
5 Designation . 6
6 Marking . 6
7 Technical specification . 6
8 Quality management system . 6
Bibliography . 8

European foreword
This document (EN 4012:2025) has been prepared by ASD-STAN.
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
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 April 2026, and conflicting national standards shall be
withdrawn at the latest by April 2026.
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.
This document supersedes EN 4012:2004.
This document inclu
...

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SIST EN 4012:2026 표준은 항공 우주 응용 분야에서 사용되는 NI-PH2601 합금으로 제작된 자가 잠금 바이헥사곤 너트의 특성을 명확하게 정의하고 있습니다. 이 표준은 특히 MoS2로 코팅된 너트의 성능을 강조하며, 높은 내열성과 강도를 요구하는 항공 우주 산업에서의 응용 가능성을 넓혀줍니다. 이 표준의 중요한 강점 중 하나는 1,550 MPa의 압축 강도와 425 °C의 내열 온도를 기준으로 명확한 분류를 제공한다는 것입니다. 이는 고온 환경에서의 안정성이 필수적인 항공 우주 분야에서 매우 중요합니다. 또한, NI-PH2601 합금은 뛰어난 내식성과 강도를 보장하여 장기적인 신뢰성을 확보할 수 있습니다. SIST EN 4012:2026는 항공 우주 산업의 표준화를 통해 부품의 신뢰성과 안전성을 높이는 데 기여합니다. 이러한 특성은 특히 우주선, 항공기 및 관련 구조물의 설계 및 제작 시 중요한 요소가 됩니다. 따라서 이 표준은 항공 우주 분야에서 필수적인 기술적 요구를 충족시키며, 최신 기술 발전에 대응하는 기준을 제공합니다.

SIST EN 4012:2026は、航空宇宙分野における特定のニーズに応える重要な標準です。この標準は、NI-PH2601（Inconel 718）製の自己ロック型の二十角ナットに関する特性を明確に定義しています。具体的には、MoS2コーティングが施されたこれらのナットは、高温環境下での使用において信頼性を保証します。 この標準の強みは、まずその耐熱性にあります。分類された特性、すなわち1 550 MPaの引張強度および425 °Cまでの耐久温度範囲は、厳しい航空宇宙環境での性能を考慮した結果であり、これにより設計者は大きな信頼を持って製品を利用することができます。また、MoS2コーティングは摩耗の低減や潤滑特性の向上に寄与し、ナットの長寿命化を図っています。 さらに、このSIST EN 4012:2026の文書は、明確な範囲と用途が示されているため、航空宇宙業界の専門家にとって非常に価値のあるリソースとなっています。標準化された特性により、製品の互換性や供給の一貫性が保たれ、業界全体の信頼性向上に寄与しています。 このように、SIST EN 4012:2026は、航空宇宙産業における部品の品質と信頼性を高めるための基盤を提供しており、特に高度な技術が求められる場面での重要性を再確認させるものです。

Die Norm SIST EN 4012:2026 legt die Eigenschaften von selbstsichernden, bihexagonalen Schraubenmuttern in der Legierung NI-PH2601 fest, die mit MoS2 beschichtet sind und speziell für die Luftfahrtindustrie entwickelt wurden. Die Norm ist von großer Bedeutung, da sie nicht nur die technischen Anforderungen für diese speziellen Schraubenmuttern definiert, sondern auch die Klassifizierung von 1 550 MPa bei Raumtemperatur und 425 °C umfasst. Ein wesentlicher Stärke dieser Norm ist die detaillierte Spezifikation der Materialeigenschaften und der Beschichtung, die entscheidend für die Leistung und Zuverlässigkeit in anspruchsvollen Einsatzbereichen der Luftfahrt ist. Die Verwendung von NI-PH2601, einer hitzebeständigen Nickelbasislegierung, garantiert eine hervorragende Festigkeit und Korrosionsbeständigkeit, was für die Sicherheit und Langlebigkeit von Luftfahrzeugen unerlässlich ist. Darüber hinaus ist die Selbstsicherung der bihexagonalen Schraubenmuttern ein weiterer kritischer Aspekt, der in der Norm behandelt wird. Diese Funktion sorgt dafür, dass sich die Schraubenmuttern unter Vibrationen und anderen mechanischen Beanspruchungen nicht lösen, was die Betriebssicherheit erhöht und potenzielle Gefahren in der Luftfahrt minimiert. Die Relevanz der SIST EN 4012:2026 in der Luftfahrtindustrie ist unbestritten, da viele Komponenten von Luftfahrzeugen extremen Bedingungen ausgesetzt sind, und somit höchste Anforderungen an die verwendeten Materialien und Verbindungselemente gestellt werden. Diese Norm bietet Herstellern und Ingenieuren die notwendige Orientierung, um Produkte zu entwickeln, die zuverlässig und leistungsfähig sind. Insgesamt stellt die SIST EN 4012:2026 eine wichtige Grundlage für die Verwendung von bihexagonalen, selbstsichernden Schraubenmuttern in der Luftfahrt dar und trägt dazu bei, die Standards in der Branche auf ein hohes Niveau zu heben. Die Kombination aus spezifizierten Materialeigenschaften, angemessener Klassifizierung und sicherheitsrelevanten Funktionen ist ein großer Vorteil für alle, die im Bereich der Luftfahrt tätig sind.

La norme SIST EN 4012:2026 se distingue par son approche exhaustive en matière de spécifications relatives aux écrous bihexagonaux auto-bloquants en alliage de nickel résistant à la chaleur, particulièrement le NI-PH2601 (Inconel 718), revêtus de MoS2. Cette norme s'adresse spécifiquement aux applications aéronautiques, ce qui souligne son importance dans un secteur où la sécurité et la fiabilité des composants sont primordiales. L'une des principales forces de la norme est sa classification rigoureuse, indiquant une résistance à la traction de 1 550 MPa à température ambiante et de 425 °C. Cette caractéristique garantit non seulement des performances optimales, mais également une longévité accrue des composants dans des environnements thermiquement et mécaniquement exigeants. De plus, l'utilisation de l'alliage Inconel 718 renforce la durabilité et la résistance à la corrosion, ce qui est essentiel pour les équipements aérospatiaux soumis à des conditions extrêmes. En termes de pertinence, la norme SIST EN 4012:2026 répond à un besoin crucial de standardisation dans l'industrie aéronautique, où chaque pièce doit répondre à des critères stricts pour garantir l'intégrité et la sécurité des aéronefs. En établissant des critères clairs pour les écrous en NI-PH2601, cette norme permet aux fabricants de s'assurer que leurs produits respectent des standards élevés, facilitant ainsi la confiance des ingénieurs et des concepteurs dans le choix des composants. En résumé, la SIST EN 4012:2026 se révèle être une norme essentielle pour les écrous bihexagonaux auto-bloquants en alliage de nickel, apportant précision, robustesse et sécurité aux applications aéronautiques, et répondant parfaitement aux exigences techniques du secteur.

The SIST EN 4012:2026 standard establishes critical specifications for self-locking bihexagonal nuts made from heat resisting nickel base alloy NI-PH2601, commonly known as Inconel 718, which is essential for aerospace applications. The standard meticulously outlines the characteristics of these fasteners, particularly their performance at ambient temperatures and at elevated conditions up to 425 °C, with a notable classification strength of 1,550 MPa. One of the primary strengths of this standard lies in its rigorous detailing of the mechanical and physical properties of the bihexagonal nuts. By incorporating a MoS2 coating, the standard addresses the necessity for enhanced lubrication and friction reduction, which directly contributes to the reliability and safety of aerospace components. This emphasis on durability and performance under various thermal conditions makes it particularly relevant for high-stakes aerospace environments where failure is not an option. The relevance of SIST EN 4012:2026 is underscored by the growing demands for advanced materials in aerospace engineering. As the industry continues to evolve, there is an increasing need for components that can withstand extreme conditions while maintaining integrity and performance. This standard not only fills a vital gap in the existing regulatory framework but also provides manufacturers and engineers with a reliable guideline to ensure the safety and efficacy of fasteners used in aerospace applications. In summary, the SIST EN 4012:2026 standard serves as an indispensable resource that harmonizes the manufacturing and application of self-locking bihexagonal nuts in NI-PH2601, ensuring they meet stringent aerospace standards amidst demanding operational environments. The focus on both mechanical strength and thermal resistance reinforces its position as a crucial document in the aerospace standards landscape.