SIST EN 4321:2005

Aerospace series - Bolts, double hexagon head with lockwire holes, relieved shank, long thread, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), silver plated - Classification: 1 550 MPa (at ambient temperature) / 650 °C

This standard specifies the characteristics of double hexagon headed bolts with lockwire holes, relieved shank and long thread, in NI-PH2601, silver plated, for aerospace applications.
Classification: 1 550 MPa  ) / 650 °C  )

Luft- und Raumfahrt - Zwölfkantschrauben, mit Löchern für Sicherungsdraht, Dünnschaft, langes Gewinde, aus hochwarmfester Nickelbasislegierung NI-PH2601 (Inconel 718), versilbert - Klasse: 1 550 MPa (bei Raumtemperatur)/650 °C

Diese Norm legt die Eigenschaften von Zwölfkantschrauben mit Löchern für Sicherungsdraht, Dünnschaft und langem Gewinde, aus NI PH2601, versilbert, für Anwendungen in der Luft- und Raumfahrt fest.
Klasse: 1 550 MPa )/650 °C ).

Série aérospatiale - Vis a tete bihexagonale avec trous de fil frein, fut dégagé, filetage long, en alliage résistant a chaud a base de nickel NI-PH2601 (Inconel 718), argentées - Classification : 1 550 MPa (a température ambiante) / 650 °C

Aerospace series - Bolts, double hexagon head with lockwire holes, relieved shank, long thread, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), silver plated - Classification: 1 550 MPa (at ambient temperature) / 650 °C

General Information

• Status: Published
• Publication Date: 31-May-2005
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: SS SPL - Technical Board for the general field
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Jun-2005
• Due Date: 01-Jun-2005
• Completion Date: 01-Jun-2005
• Ref Project: EN 4321:2004 - Aerospace series - Bolts, double hexagon head with lockwire holes, relieved shank, long thread, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), silver plated - Classification: 1 550 MPa (at ambient temperature) / 650 °C

Relations

• Replaces: SIST EN 4321:2004 - Aerospace series - Bolts, double hexagon head with lockwire holes, relieved shank, long thread, in heat resisting nickelbase alloy NI-PH2601 (Inconel 718), silver plated - Classification: 1 550 MPa (at ambient temperature) / 650°C
• Effective Date: 01-Jun-2005

Overview

EN 4321:2004 is a CEN (AECMA) aerospace standard that defines the characteristics of double hexagon head bolts with lockwire holes, relieved shank and long thread manufactured from the heat‑resisting nickel‑base alloy NI‑PH2601 (Inconel 718) and silver plated. The standard is intended for aerospace applications requiring high static strength and elevated temperature performance. Classification: 1 550 MPa (ambient tensile strength) and service/test temperature up to 650 °C.

Key topics and requirements

• Material: Alloy NI‑PH2601 (Inconel 718) produced according to EN 3666 or EN 2952, with the final heat treatment and mechanical properties to conform to EN 3666.
• Mechanical classification: Minimum tensile strength ~1 550 MPa at ambient temperature; maximum test temperature 650 °C.
• Configuration & dimensions: Geometry, tolerances and masses specified by the standard (see Figure 1, Tables 1–2). Dimensions are in millimetres and apply after silver plating.
• Threads and drives:
  • MJ thread limit dimensions per ISO 5855‑2.
  • Rolled external threads conform to ISO 3353‑1 (lead and runout threads).
  • Bihexagonal wrenching configuration in conformity with ISO 4095.
• Surface treatment: Electrolytic silver plating per EN 2786. Mandatory thickness on the thread: 3 µm to 6 µm measured at the pitch diameter; other areas should have complete coverage (no specific thickness requirement).
• Marking & designation:
  • Product marking follows EN 2424.
  • Example designation format: BOLT EN4321-080060 (standard number + thread code + length code).
• Technical specification & conformity: Technical specification references include EN 3833 and normative standards listed in the document.

Applications and users

EN 4321:2004 applies to high‑performance aerospace fasteners used where:

• High tensile strength and heat resistance are required (e.g., hot‑section components, structural assemblies exposed to elevated temperatures).
• Positive locking via lockwire is needed for safety‑critical joints.

Typical users:

• Aerospace fastener manufacturers and heat‑treaters producing Inconel 718 bolts.
• Design and structural engineers specifying high‑temperature fasteners.
• Procurement and quality assurance teams ensuring compliance with aerospace standards.
• Maintenance, repair and overhaul (MRO) organizations that replace or inspect certified fasteners.

Related standards

Key normative references included in EN 4321:2004:

• ISO 3353‑1 (rolled external threads)
• ISO 4095 (bihexagonal drives)
• ISO 5855‑2 (MJ threads)
• EN 2424 (marking of aerospace products)
• EN 2786 (electrolytic silver plating of fasteners)
• EN 2952 / EN 3666 (NI‑PH2601 bar/heat treatment)
• EN 3833 (technical specification for similar Inconel bolts)

Keywords: EN 4321:2004, aerospace bolts, Inconel 718, NI‑PH2601, double hexagon head, lockwire holes, silver plated, relieved shank, long thread, high‑temperature fasteners.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2005
1DGRPHãþD
SIST EN 4321:2004
Aerospace series - Bolts, double hexagon head with lockwire holes, relieved
shank, long thread, in heat resisting nickel base alloy NI-PH2601 (Inconel 718),
silver plated - Classification: 1 550 MPa (at ambient temperature) / 650 °C
Aerospace series - Bolts, double hexagon head with lockwire holes, relieved shank, long
thread, in heat resisting nickel base alloy NI-PH2601 (Inconel 718), silver plated -
Classification: 1 550 MPa (at ambient temperature) / 650 °C
Luft- und Raumfahrt - Zwölfkantschrauben, mit Löchern für Sicherungsdraht, Dünnschaft,
langes Gewinde, aus hochwarmfester Nickelbasislegierung NI-PH2601 (Inconel 718),
versilbert - Klasse: 1 550 MPa (bei Raumtemperatur)/650 °C
Série aérospatiale - Vis a tete bihexagonale avec trous de fil frein, fut dégagé, filetage
long, en alliage résistant a chaud a base de nickel NI-PH2601 (Inconel 718), argentées -
Classification : 1 550 MPa (a température ambiante) / 650 °C
Ta slovenski standard je istoveten z: EN 4321:2004
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.

EUROPEAN STANDARD
EN 4321
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2004
ICS 49.030.20 Supersedes EN 4321:2003
English version
Aerospace series - Bolts, double hexagon head with lockwire
holes, relieved shank, long thread, in heat resisting nickel base
alloy NI-PH2601 (Inconel 718), silver plated - Classification: 1
550 MPa (at ambient temperature) / 650° C
Série aérospatiale - Vis à tête bihexagonale avec trous de Luft- und Raumfahrt - Zwölfkantschrauben mit Löcher für
fil frein, fût dégagé, filetage long, en alliage résistant à Sicherungsdraft, Dünnschaft, langes Gewinde, aus
chaud à base de nickel NI-PH2601 (Inconel 718), hochwarmfester Nickelbasislegierung NI-PH2601 (Inconel
argentées - Classification : 1 550 MPa (à température 718), versilbert - Klasse: 1 550 MPa (bei Raumtemperatur)
ambiante) / 650° C / 650° C
This European Standard was approved by CEN on 11 September 2003.

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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 4321:2004: E
worldwide for CEN national Members.

Contents                                                                         Page

Foreword.3
1 Scope .4
2 Normative references .4
3 Required characteristics.4
4 Designation .9
5 Marking .9
6 Technical specification .9
Foreword
This document (EN 4321:2004) has been prepared by the European Association of Aerospace
Manufacturers - Standardization (AECMA-STAN).
After enquiries and votes carried out in accordance with the rules of this Association, this Standard has
received the approval of the National Associations and the Official Services of the member countries of
AECMA, 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 May 2005, and conflicting national standards shall be withdrawn at
the latest by May 2005.
This document supersedes EN 4321:2003.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and the United Kingdom.
1 Scope
This standard specifies the characteristics of double hexagon headed bolts with lockwire holes, relieved
shank and long thread, in NI-PH2601, silver plated, for aerospace applications.
1) 2)
Classification: 1 550 MPa / 650 °C
2 Normative references
The following referenced documents are indispensable for the application 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.
ISO 3353-1, Aerospace – Lead and runout threads – Part 1: Rolled external threads
ISO 4095, Aerospace – Bihexagonal drives – Wrenching configuration – Metric series
ISO 5855-2, Aerospace – MJ threads – Part 2: Limit dimensions for bolts and nuts
EN 2424, Aerospace series – Marking of aerospace products
3)
EN 2786, Aerospace series – Electrolytic silver plating of fasteners
EN 2952, Aerospace series – Heat resisting alloy NI-PH2601 – Solution treated and cold worked – Bar for
3)
forged fasteners – D ≤ 50 mm – 1 270 MPa ≤ R ≤ 1 550 MPa
m
EN 3666, Aerospace series – Heat resisting alloy NI-PH2601 – Solution treated and cold worked – Bar for
3)
forged fasteners – D ≤ 50 mm – 1 550 MPa ≤ R ≤ 1 830 MPa
m
EN 3833, Aerospace series – Bolts, MJ threads, in heat resisting nickel base alloy NI-PH2601 (Inconel
718), passivated – Classification: 1 550 MPa (at ambient temperature) / 650 °C – Technical
specification
3 Required characteristics
3.1 Configuration – Dimensions – Tolerances – Masses
See Figure 1 and Tables 1 and 2.
Dimensions and tolerances are in millimetres. They apply after silver plating.
3.2 Materials
EN 3666 or EN 2952 with exception of final heat
...