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

EN 3327:2026 is a CEN European Standard for uncoated aerospace bolts with a double hexagon head, close tolerance, medium thread length and MJ-thread, made from heat-resisting nickel base alloy NI-P100HT (Inconel 718). It classifies these bolts for 1 275 MPa/650 °C and sets the dimensions, material, marking and technical specification for parts used mainly in aerospace fastening systems stressed in shear.

What does EN 3327:2026 specify?

EN 3327:2026 specifies the dimensions of uncoated double hexagon head bolts, close tolerance, medium thread length, in heat-resisting nickel base alloy NI-P100HT for aerospace applications. The parts are intended for a maximum test temperature of 650 °C and for fastening systems mainly stressed in shearing force.

The document is organized into seven clauses:

• Scope
• Normative references
• Terms and definitions
• Required characteristics
• Designation
• Marking
• Technical specification

Clause 4 is the main technical part. It covers configuration, dimensions, tolerances, mass, material, and surface treatment.

What are the key requirements of EN 3327:2026?

Geometry, dimensions and mass

EN 3327:2026 requires the bolt configuration to follow Figure 1, with dimensions, tolerances and mass taken from Figure 1 and Tables 1 and 2. Details of form that are not stated are left to the manufacturer’s option, so the standard fixes the critical envelope but allows non-critical shaping to be chosen by the maker.

In practice, this means the supplier must control the external form, length codes, mass and thread-related geometry exactly enough to match the listed size family. Clause 4.1 also requires sharp edges to be broken within a defined small range, which matters for handling, fit and damage prevention.

Thread and drive features

EN 3327:2026 ties the bihexagonal configuration to ISO 4095 over the minimum length T, and it uses ISO 3353-1 for thread runout and lead thread features. It also adjusts how runout and datum are handled when the shank length is shorter than the nominal shank diameter D.

For the user, this matters because the wrenching drive, runout and reference axis affect tool engagement, assembly clearance and inspection method. Clause 4.1 also modifies the thread major diameter tolerance as shown in Figure 1, so the figure is part of the compliance check, not just an illustration.

Material and surface condition

EN 3327:2026 specifies heat resisting nickel base alloy NI-P100HT in accordance with EN 2952, or SAE AMS5662, or TR 3775. Clause 4.3 requires no surface treatment.

In practice, the buyer or manufacturer must verify the alloy route used for the fastener and must not apply a coating or finish unless another approved document allows it. This is important for high-temperature performance and for matching the intended uncoated product form.

Designation, marking and technical specification

EN 3327:2026 requires each bolt to be designated by the standard number plus a diameter code and a length code, as shown in the designation example. Clause 6 requires marking in accordance with EN 2424, Style A. Clause 7 says the bolts shall also meet EN 2583.

This means the product has to be identified in a way that links the physical part to the standard size, and its marking must follow the aerospace marking rule used across the series.

Which standards are used with EN 3327:2026?

EN 3327:2026 cites these documents in Clause 2:

• EN 2424 - marking of aerospace products
• EN 2583 - technical specification for MJ-thread bolts in the same alloy family and temperature classification
• EN 2952 - material condition for NI-PH2601 bar for forged fasteners
• ISO 3353-1 - lead and runout threads for rolled external threads
• ISO 4095 - bihexagonal drives and wrenching configuration
• ISO 5855-1 and ISO 5855-2 - general requirements and limit dimensions for MJ threads
• SAE AMS5662 - alternative material specification
• TR 3775 - materials for aerospace bolts and pins

Who uses EN 3327:2026?

EN 3327:2026 is used by aerospace fastener manufacturers, design engineers, quality and inspection teams, procurement staff and maintenance organizations. They use it to specify, make, buy and verify bolts for shear-loaded aerospace joints where the head form, thread system, alloy condition, marking and size coding must be controlled consistently.

What changed in EN 3327:2026 from the previous edition?

EN 3327:2026 supersedes EN 3327:2008. The foreword states two significant technical changes:

• SAE AMS5662 was added in Clause 2 and in Clause 4.2 for material
• 3.4, “Thread surface”, was removed

What does the EN 3327:2026 document contain?

EN 3327:2026 contains the scope, the list of normative references, the required characteristics, designation rules, marking rules and the technical specification link to EN 2583. Its technical core is Figure 1, which defines the bolt configuration, Table 1, which gives the size family and key dimensions, and Table 2, which gives lengths and masses for the permitted diameter and length codes.

The document also includes the example designation, notes that support interpretation of the figure and tables, and the material statement in Clause 4.2. For users, this is the part to consult when checking whether a given bolt design, marking or declared mass matches the standard.

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
...