kSIST FprEN 3293:2026

• Abstract:

  This document specifies the dimensions of uncoated T-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: Not Published
• Public Enquiry End Date: 09-Sep-2025
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 10-Jul-2026
• Due Date: 28-Aug-2026
• Completion Date: 10-Jul-2026
• Ref Project: FprEN 3293 - Aerospace series - Bolts, T-head, close tolerance, medium thread length, in heat resisting nickel base alloy NI-P100HT (Inconel 718), uncoated - Classification: 1 275 MPa/650 °C

• Revises: SIST EN 3293:2008 - Aerospace series - Bolts, T-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

kSIST FprEN 3293:2026 is a European standard developed by SIST for the aerospace industry, specifying the dimensions and requirements for uncoated T-head bolts with close tolerance, medium thread length, and MJ threading, manufactured from heat-resisting nickel base alloy NI-P100HT (Inconel 718). These bolts are classified for a strength of 1,275 MPa at a service temperature of up to 650 °C, making them highly suitable for aerospace fastening systems primarily subjected to shearing forces.

In aerospace engineering, consistent and precise fastener specifications are essential for safety, reliability, and performance. This standard supersedes EN 3293:2008 and provides updated requirements to align with latest materials and industry practices.

Key Topics

• T-Head Bolt Design
  The standard covers T-head bolt design, focusing on uncoated, close tolerance bolts with medium thread length using MJ threads, tailored for aerospace applications.

• Material Specifications
  Bolts specified under kSIST FprEN 3293:2026 are manufactured from nickel base alloy NI-P100HT (Inconel 718), known for excellent heat resistance and high mechanical strength at elevated temperatures, conforming to material requirements such as SAE AMS5662.

• Configuration and Dimensions
  The document prescribes the configuration, tolerances, and mass for various nominal diameters and lengths, ensuring compatibility and interchangeability in aerospace assemblies. Detailed tables specify the critical dimensions for manufacturing and inspection.

• Performance Classification
  Fasteners are classified for operational strength of 1,275 MPa and maximum test temperature of 650 °C, supporting use in demanding environments.

• Marking and Designation
  The standard specifies the designation format for bolt identification as well as marking requirements per EN 2424, ensuring traceability and compliance.

Applications

• Aerospace Fastening Systems
  Primarily used in aerospace structures, these T-head bolts provide precise, strong, and consistent fastening, particularly where components are mainly stressed in shear. Typical applications include airframe and engine assemblies requiring heat resistance and close tolerance fasteners.

• High-Temperature Environments
  Thanks to the material's ability to maintain mechanical integrity at elevated temperatures, these bolts are ideal for use in locations exposed to engine heat or similar extreme conditions.

• Critical Structural Attachments
  The close tolerance and strength classification of these bolts make them suitable for critical load-bearing joints where failure is not an option and where high shear strength is critical.

Related Standards

• EN 2424: Marking of aerospace products
• EN 2583: Bolts, MJ threads, in heat resisting nickel base alloy NI-PH2601 (Inconel 718) – Technical specification
• ISO 3353-1: Aerospace – Lead and runout threads – Rolled external threads
• ISO 5855-1 & ISO 5855-2: Aerospace – MJ threads – General requirements and limit dimensions
• TR 3775: Bolts and pins – Materials
• SAE AMS5662: Nickel Alloy, Corrosion- and Heat-Resistant

Practical Value

Adhering to kSIST FprEN 3293:2026 enables aerospace manufacturers and suppliers to ensure high levels of safety, performance, and interoperability for fastening systems exposed to high stress and temperature. Standardized specification simplifies procurement, inspection, and maintenance, reducing costs and risks associated with non-standard fasteners. Compliance with this standard also supports international harmonization and quality assurance in aerospace supply chains.

SLOVENSKI STANDARD
oSIST prEN 3293:2025
01-september-2025
Aeronavtika - Sorniki, glava T, 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, T-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 - T-Kopf-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: prEN 3293
ICS:
49.030.20 Sorniki, vijaki, stebelni vijaki Bolts, screws, studs
oSIST prEN 3293:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 3293:2025
oSIST prEN 3293:2025
DRAFT
EUROPEAN STANDARD
prEN 3293
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2025
ICS 49.030.20 Will supersede EN 3293:2008
English Version
Aerospace series - Bolts, T-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 - T-Kopf-Passschrauben, mittlere
bihexagonale, à filetage moyen, en alliage résistant à Gewindelänge, aus hochwarmfester
chaud à base de nickel NI-P100HT (Inconel 718), non Nickelbasislegierung NI-P100HT (Inconel 718), blank -
revêtu - Classification : 1 275 MPa/650 °C Klasse: 1 275 MPa/650 °C
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-
STAN.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

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. prEN 3293:2025 E
worldwide for CEN national Members.

oSIST prEN 3293:2025
prEN 3293:2025 (E)
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 . 8
4.3 Surface treatment . 8
5 Designation . 8
6 Marking . 8
7 Technical specification . 8

oSIST prEN 3293:2025
prEN 3293:2025 (E)
European foreword
This document (prEN 3293:2025) 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 document is currently submitted to the CEN Enquiry.
This document will supersede EN 3293:2008.
prEN 3293:2025 includes the following significant technical changes with respect to EN 3293:2008:
— material standard SAE AMS5662 added;
— 3.4 “Thread surface” removed.
oSIST prEN 3293:2025
prEN 3293:2025 (E)
1 Scope
This document specifies the dimensions of uncoated T-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.
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
ISO 3353-1, Aerospace — Lead and runout threads — Part 1: Rolled external threads
ISO 5855-1, Aerospace — MJ threads — Part 1: General requirements
ISO 5855-2, Aeros
...