SIST EN 3687:2026

Aerospace series - Bolts, normal hexagon head, relieved shank, long thread, in heat resisting steel FE-PA2601 (A286), silver plated - Classification: 1 100 MPa/650 °C

This document specifies the characteristics of silver-plated Bolts normal Hexagon Head with relieved shank and long thread, in heat resisting steel FE-PA92HT (A286), tensile strength class 1 100 MPa at room temperature. The maximum test temperature of the material is 650 °C.

Luft- und Raumfahrt - Sechskantschrauben, Dünnschaft, langes Gewinde, aus hochwarmfestem Stahl FE-PA2601 (A286), versilbert - Klasse: 1 100 MPa/650 °C

Dieses Dokument legt die Eigenschaften von Sechskantschrauben mit Dünnschaft und langem Gewinde aus hochwarmfestem Stahl FE-PA2601 (A286), versilbert, Zugfestigkeitsklasse 1 100 MPa bei Raumtemperatur, fest. Die maximale Prüftemperatur des Werkstoffes beträgt 650 °C.

Série aérospatiale - Vis à tête hexagonale normale, tige dégagée, filetage long, en acier résistant à chaud FE-PA2601 (A286), argentées - Classification : 1 100 MPa/650 °C

Le présent document spécifie les caractéristiques des vis argentées, à tête hexagonale normale, tige dégagée, filetage long, en acier résistant à chaud FE-PA2601 (A286), de classe de résistance à la traction de 1 100 MPa à température ambiante. La température maximale d’essai du matériau est de 650 °C.

Aeronavtika - Sorniki, normalna šestroba glava, tanko steblo, dolg navoj, iz toplotno odpornega jekla FE-PA2601 (A286), posrebreni - Klasifikacija: 1100 MPa/650 °C

Ta dokument določa lastnosti srebrno prevlečenih vijakov z običajno šesterokotno glavo, z razbremenjenim steblom in dolgim navojem, iz toplotno odpornega jekla FE-PA92HT (A286), z natezno trdnostjo razreda 1 100 MPa pri sobni temperaturi. Najvišja preskusna temperatura materiala je 650 °C.

General Information

• Status: Published
• Public Enquiry End Date: 02-Jul-2024
• Publication Date: 06-Apr-2026
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 27-Mar-2026
• Due Date: 01-Jun-2026
• Completion Date: 07-Apr-2026
• Ref Project: EN 3687:2026 - Aerospace series - Bolt, normal hexagon head, relieved shank, long thread, in heat resisting steel FE-PA2601 (A286), silver plated - Classification: 1 100 MPa/650 °C

Relations

• Refers: SIST EN 2786:2008 - Aerospace series - Electrolytic silver plating of fasteners
• Effective Date: 25-Mar-2026
• Refers: SIST EN 2424:2008 - Aerospace series - Marking of aerospace products
• Effective Date: 25-Mar-2026
• Refers: SIST EN 3685:2019 - Aerospace series - Bolts in heat resisting steel FE-PA2601 (A286) - Classification: 1 100 MPa/650 °C - Technical specification
• Effective Date: 25-Mar-2026
• Refers: SIST EN 3761:2020 - Aerospace series - Heat resisting alloy FE-PA2601 - Softened and cold worked - Bar for forged fasteners - D ≤ 50 mm - 1 100 MPa ≤ Rm ≤ 1 300 MPa
• Effective Date: 25-Mar-2026
• Referred By: SIST EN 14439:2025 - Cranes - Tower cranes
• Effective Date: 28-Jan-2026
• Revises: SIST EN 3687:2012 - Aerospace series - Bolts, normal hexagon head, relieved shank, long thread, in heat resisting steel FE-PA92HT (A286), silver plated - Classification: 1100 MPa/650°C
• Effective Date: 11-Oct-2023
• Revises: SIST EN 3687:2012/AC:2012 - Aerospace series - Bolts, normal hexagon head, relieved shank, long thread, in heat resisting steel FE-PA2601 (A286), silver plated - Classification: 1 100 MPa/650 °C
• Effective Date: 11-Oct-2023

Overview

The kSIST FprEN 3687:2025:2024 standard, issued by CEN, defines the specifications for aerospace-grade bolts featuring a normal hexagon head, relieved shank, and long thread. These bolts are manufactured from the heat-resisting steel FE-PA2601 (A286), which is silver plated to enhance surface properties and corrosion resistance. Classified under tensile strength class 1,100 MPa at room temperature and tested up to a maximum temperature of 650 °C, these bolts are engineered for demanding aerospace applications requiring both mechanical reliability and heat resistance.

This updated standard supersedes the previous EN 3687:2010 and incorporates adjustments such as refined surface roughness requirements and corrected dimensional values to ensure precision engineering and compliance with contemporary aerospace manufacturing needs.

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Key Topics

• Material Quality
  The bolts are made from heat resisting alloy FE-PA2601 (A286) according to EN 3761, ensuring high tensile strength (1100 MPa) and superior performance in temperatures up to 650 °C.

• Bolt Design
  The configuration features a normal hexagon head, a relieved shank to reduce stress concentrations, and a long thread for improved engagement. Detailed dimensions, tolerances, and surface roughness standards are specified precisely for manufacturing consistency.

• Surface Treatment
  A silver plating coat applied per EN 2786 Category A with a thickness of 3–6 µm on thread flanks ensures corrosion resistance and surface conductivity. Surface roughness requirements prescribe a maximum Ra of 0.8 µm on bearing surfaces and 3.2 µm on other surfaces before plating.

• Marking and Designation
  Marking complies with EN 2424, guaranteeing traceability essential for aerospace quality control. The bolt designation format simplifies identification by diameter and length codes, streamlining procurement and assembly processes.

• Standards Alignment
  The specification incorporates references to related aerospace standards and ISO norms for thread forms and dimensions, ensuring interoperability and standardized production quality.

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Applications

The kSIST FprEN 3687:2025:2024 bolts are ideal for high-performance aerospace applications where strength, temperature endurance, and corrosion resistance are critical. Typical uses include:

• Aircraft Structural Assemblies
  Bolts securing engine mounts, airframe structures, and other components exposed to thermal stress and vibration.

• Aeronautical Engine Components
  Fastening parts in heat-affected zones requiring sustained mechanical properties at elevated temperatures.

• Space Industry Hardware
  Assemblies in spacecraft where temperature fluctuation and material reliability are paramount.

• High-Temperature Industrial Equipment
  Beyond aerospace, these bolts can be used in power generation equipment and other industrial machinery requiring heat resistant fasteners.

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Related Standards

• EN 3761: Specifications for heat-resisting alloy FE-PA2601 bars for forged fasteners.
• EN 2786: Guidelines on electrolytic silver plating of fasteners to ensure corrosion resistance.
• EN 3685: Technical specifications for bolts made from heat resisting steel FE-PA2601 (A286), complementing EN 3687 for design and performance aspects.
• EN 2424: Marking requirements for aerospace products, essential for traceability.
• ISO 3353-1: Standards for rolled external threads, defining thread forms for aerospace fasteners.
• ISO 5855 (Parts 1 & 2): MJ thread requirements covering general specifications and limit dimensions.
• ASME B46.1: Surface texture and roughness standards referenced for quality control prior to plating.

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Keywords: aerospace bolts, heat resisting steel FE-PA2601, silver plated bolts, hexagon head bolts, high-temperature fasteners, aerospace fastener standards, tensile strength 1100 MPa, bolt surface roughness, aerospace series bolts, CEN standards.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2026
Aeronavtika - Sorniki, normalna šestroba glava, tanko steblo, dolg navoj, iz
toplotno odpornega jekla FE-PA2601 (A286), posrebreni - Klasifikacija: 1100
MPa/650 °C
Aerospace series - Bolts, normal hexagon head, relieved shank, long thread, in heat
resisting steel FE-PA2601 (A286), silver plated - Classification: 1 100 MPa/650 °C
Luft- und Raumfahrt - Sechskantschrauben, Dünnschaft, langes Gewinde, aus
hochwarmfestem Stahl FE-PA2601 (A286), versilbert - Klasse: 1 100 MPa/650 °C
Série aérospatiale - Vis à tête hexagonale normale, tige dégagée, filetage long, en acier
résistant à chaud FE-PA2601 (A286), argentées - Classification : 1 100 MPa/650 °C
Ta slovenski standard je istoveten z: EN 3687:2026
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 3687
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2026
EUROPÄISCHE NORM
ICS 49.030.20 Supersedes EN 3687:2010
English Version
Aerospace series - Bolt, normal hexagon head, relieved
shank, long thread, in heat resisting steel FE-PA2601
(A286), silver plated - Classification: 1 100 MPa/650 °C
Série aérospatiale - Vis à tête hexagonale normale, tige Luft- und Raumfahrt - Sechskantschraube, Dünnschaft,
dégagée, filetage long, en acier résistant à chaud FE- langes Gewinde, aus hochwarmfestem Stahl FE-
PA2601 (A286), argentées - Classification : 1 100 PA2601 (A286), versilbert - Klasse: 1 100 MPa/650 °C
MPa/650 °C
This European Standard was approved by CEN on 19 January 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 3687:2026 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 . 4
4.1 Configuration – Dimensions – Tolerances . 4
4.2 Surface roughness . 4
4.3 Material . 5
4.4 Surface treatment . 5
5 Designation . 11
6 Marking . 11
7 Technical specification . 11
Bibliography . 12

European foreword
This document (EN 3687:2026) 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 September 2026, and conflicting national standards
shall be withdrawn at the latest by September 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 3687:2010 and EN 3687:2010/AC:2011.
This document includes the following significant technical changes with respect to EN 3687:2010 and
EN 3687:2010/AC:2011:
— the surface roughness requirements have been replaced from Figure 1 to the text;
— values for S at diameter code 050 in Table 1 have been corrected.
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 characteristics of silver-plated bolts with normal hexagon head, relieved
shank and long thread, in heat resisting steel FE-PA2601 (A286), tensile strength class 1 100 MPa at
room temperature. The maximum test temperature of the material is 650 °C.
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 2424:2008, Aerospace series — Marking of aerospace products
EN 2786, Aerospace series — Electrolytic silver plating of fasteners
EN 3685, Aerospace series — Bolts in heat resisting steel FE-PA2601 (A286) — Classification:
1 100 MPa/650 °C — Technical specification
EN 3761, Aerospace series — Heat resisting alloy FE-PA2601 — Softened and cold worked — Bar for
forged fasteners — D ≤ 50 mm — 1 100 MPa ≤ R ≤ 1 300 MPa
m
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, Aerospace — MJ threads — Part 2: Limit dimensions for bolts and nuts
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at th
...