EN 3327:2026

• Abstract:

  This document specifies the dimensions of uncoated double hexagon head bolts, close tolerance, with MJ-thread, medium thread length, in heat-resisting nickel base alloy NI-P100HT for aerospace applications.; Maximum test temperature of the parts is 650 °C.; These bolts are used in aerospace fastening systems mainly stressed in shearing force.

• Status: Published
• Publication Date: 25-Aug-2026
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 3/S 2 - Fasteners
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 26-Aug-2026
• Completion Date: 26-Aug-2026
• Ref Project: SIST EN 3327:2026 - Aerospace series - Bolts, double hexagon head, close tolerance, medium thread length, in heat resisting nickel base alloy NI-P100HT (Inconel 718), uncoated - Classification: 1 275 MPa/650 °C

• Replaces: EN 3327:2008 - Aerospace series - Bolts, double hexagon head, close tolerance, medium thread length, in heat resisting nickel base alloy NI-P100HT (Inconel 718), uncoated - Classification: 1 275 MPa/650 °C
• Effective Date: 12-Feb-2025

Overview

EN 3327:2026 is a European Standard developed by CEN for the aerospace industry. It specifies the requirements for double hexagon head bolts with close tolerance and medium thread length, manufactured from heat-resisting nickel base alloy NI-P100HT (Inconel 718). These bolts are supplied uncoated and are classified for high-performance applications with a maximum test temperature of 650°C and a classification of 1 275 MPa/650°C. The design features an MJ-thread profile, ensuring high precision and robust fastening suitable for demanding aerospace environments.

Key Topics

• Double Hexagon Head Design: Facilitates secure torque application and provides accessibility in confined spaces commonly encountered in aerospace assembly.
• Close Tolerance Specification: Ensures minimal play in joints, which is crucial for components subjected to shear forces and vibration.
• Medium Thread Length: Balances resistance to stripping with ease of assembly, making these bolts versatile for various joint thicknesses.
• Nickel Base Alloy NI-P100HT (Inconel 718): Offers excellent heat resistance and mechanical strength at elevated temperatures, maintaining integrity at up to 650°C.
• Uncoated Finish: Facilitates direct contact with aerospace materials, avoiding complications associated with coating breakdown at high temperatures.
• MJ Thread Profile: Complies with aerospace standards for high fatigue resistance and reliability under dynamic loads.

Applications

These double hexagon head bolts are designed primarily for aerospace fastening systems where components are mostly subjected to shearing forces. Their characteristics lend themselves to:

• Aircraft Engine Assemblies: Suitable for high-temperature zones where materials must withstand heat and shear stresses.
• Airframe Structures: Used in areas demanding precision, close tolerance, and high reliability in joint integrity.
• Spacecraft Components: Applicable in structures where material strength and resistance to thermal cycling are essential.
• Rotating and Stationary Assemblies: Utilized in critical joints where failure could have significant safety implications.

By using NI-P100HT (Inconel 718), these bolts provide extreme durability and longevity in aggressive service conditions seen in both commercial and military aerospace platforms.

Related Standards

EN 3327:2026 is closely aligned with and may reference several important aerospace and fastener standards, including:

• EN 2424: Aerospace series - Marking of aerospace products, ensuring correct identification and traceability.
• EN 2583: Aerospace series - Bolts, MJ threads, in heat-resisting nickel base alloy NI-PH2601 (Inconel 718) - Technical specification.
• ISO 4095: Aerospace - Bihexagonal drives - Wrenching configuration (Metric series).
• ISO 5855-1/2: Aerospace - MJ threads - General requirements and limit dimensions for bolts and nuts.
• ISO 3353-1: Aerospace - Lead and runout threads - Rolled external threads.
• SAE AMS5662: Material specification for corrosion- and heat-resistant nickel alloys.
• TR 3775: Bolts and pins material requirements.

Practical Value

By adhering to EN 3327:2026, aerospace manufacturers ensure consistency, safety, and interoperability of critical fastening components. The use of close tolerance, high-strength, heat-resistant bolts directly supports lightweight yet robust airframe and engine designs, contributing to overall aircraft reliability and performance. Using standardized fasteners simplifies maintenance, supports global supply chains, and ensures compliance with industry and regulatory requirements for high-temperature, high-load aerospace applications.

Optimizing fastener selection with EN 3327:2026 improves durability while reducing the risk of mechanical failure in high-shear, high-temperature environments typical of next-generation aerospace platforms.

SLOVENSKI STANDARD
01-oktober-2026
Aeronavtika - Sorniki, dvojna šestroba glava, ozka toleranca, srednja navojna
dolžina, iz toplotnoodporne zlitine na nikljevi osnovi NI-P100HT (Inconel 718), brez
prevleke - Klasifikacija: 1 275 MPa/650 °C
Aerospace series - Bolts, double hexagon head, close tolerance, medium thread length,
in heat resisting nickel base alloy NI-P100HT (Inconel 718), uncoated - Classification: 1
275 MPa/650 °C
Luft- und Raumfahrt - Zwölfkant-Passschrauben, mittlere Gewindelänge, aus
hochwarmfester Nickelbasislegierung NI-P100HT (Inconel 718), blank - Klasse: 1 275
MPa/650 °C
Série aérospatiale - Vis de précision à tête bihexagonale, à filetage moyen, en alliage
résistant à chaud à base de nickel NI-P100HT (Inconel 718), non revêtu - Classification :
1 275 MPa/650 °C
Ta slovenski standard je istoveten z: EN 3327:2026
ICS:
49.030.20 Sorniki, vijaki, stebelni vijaki Bolts, screws, studs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 3327
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2026
EUROPÄISCHE NORM
ICS 49.030.20 Supersedes EN 3327:2008
English Version
Aerospace series - Bolts, double hexagon head, close
tolerance, medium thread length, in heat resisting nickel
base alloy NI-P100HT (Inconel 718), uncoated -
Classification: 1 275 MPa/650 °C
Série aérospatiale - Vis de précision à tête Luft- und Raumfahrt - Zwölfkant-Passschrauben,
bihexagonale, filetage moyen, en alliage résistant à mittlere Gewindelänge, aus hochwarmfester
chaud base nickel NI-P100HT (Inconel 718), non Nickelbasislegierung NI-P100HT (Inconel 718), blank -
revêtues - Classification : 1 275 MPa/650 °C Klasse: 1 275 MPa/650 °C
This European Standard was approved by CEN on 3 August 2026.

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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 3327:2026 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 . 5
4.1 Configuration, dimensions, tolerances and mass. 5
4.2 Material . 11
4.3 Surface treatment . 11
5 Designation . 11
6 Marking . 11
7 Technical specification . 11

European foreword
This document (EN 3327:2026) 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 February 2027, and conflicting national standards shall
be withdrawn at the latest by February 2027.
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 3327:2008.
— Clause 2 and 4.2, “Material”, standard SAE AMS5662 added;
— 3.4, “Thread surface”, removed.
Any feedback and questions on this document should be directed to the users’ national standards body.
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.
1 Scope
This document specifies the dimensions of uncoated double hexagon head bolts, close tolerance, medium
® 1
thread length, in heat-resisting nickel base alloy NI-P100HT (Inconel 718 ) for aerospace applications.
Maximum test temperature of the parts is 650 °C.
These bolts are to be used in aerospace fastening systems mainly stressed in shearing force.
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.
EN 2424, Aerospace series — Marking of aerospace products
EN 2583, Aerospace series — Bolts, MJ threads, in heat resisting nickel base alloy NI-PH2601
(Inconel 718) — Classification: 1 275 MPa (at ambient temperature)/650 °C — Technical specification
EN 2952, Aerospace series — Heat resisting alloy NI-PH2601 — Solution treated and cold worked — Bar
for forged fasteners — D ≤ 50 mm — 1 270 MPa ≤ R ≤ 1 550 MPa
m
ISO 3353-1, Aerospace — Lead and runout threads — Part 1: Rolled external threads
ISO 4095, Aerospace — Bihexagonal drives — Wrenching configuration — Metric series
ISO 5855-1, Aerospace — MJ threads — Part 1: General requirements
ISO 5855-2, Aerospace — MJ threads — Part 2: Limit dimensions for bolts and nuts
SAE AMS5662, Nickel Alloy, Corrosion- and Heat-Resistant, Bars, Forgings, Rings, and Stock for Forgings
and Rings 52.5Ni — 19Cr — 3.0Mo — 5.1Cb (Nb) — 0.90Ti — 0.50Al — 18Fe Consumable Electrode or
Vacuum Induction Melted 1 775 °F (968 °C) Solution Heat Treated, Precipitation-Hardenable
TR 3775, Aerospace series — Bolts and pins — Materials
3 Terms and definitions
No terms and definiti
...