SIST EN 4634:2009

• Abstract:

  This standard specifies the characteristics of screws with 100° countersunk head, with six lobes recess, short thread, in heat resisting steel FE-PA2601, passivated, for aerospace applications.

• Status: Published
• Publication Date: 20-Aug-2009
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 13-Jul-2009
• Due Date: 17-Sep-2009
• Completion Date: 21-Aug-2009
• Ref Project: EN 4634:2009 - Aerospace series - Screws, 100° countersunk head, six lobe recess, short thread, in heat resisting steel FE-PA2601 (A286), passivated - Classification: 900 MPa (at ambient temperature) / 650 °C

• Refers: SIST EN 3911:2014 - Aerospace series - Six lobe recess - Geometrical definition
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2399:2008 - Aerospace series - Heat resisting steel FE-PA2601 (X4NiCrTiMoV26-15) - Rm ≥ 900 MPa - Bars for forged bolts - D ≤ 25 mm
• Effective Date: 28-Jan-2026
• Refers: SIST EN 840-6:2004+A1:2008 - Mobile waste containers - Part 6: Safety and health requirements
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2516:2024 - Aerospace series - Passivation of corrosion resisting steels and decontamination of nickel or cobalt base alloys
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2424:2008 - Aerospace series - Marking of aerospace products
• Effective Date: 28-Jan-2026
• Refers: SIST EN 14460:2006 - Explosion resistant equipment
• Effective Date: 28-Jan-2026

SIST EN 4634:2009 is the Slovenian adoption of EN 4634:2009, published by SIST. It specifies aerospace screws with a 100° countersunk head, six lobe recess, short thread, made from heat resisting steel FE-PA2601 (A286), passivated, and classified as 900 MPa at ambient temperature / 650 °C. The standard tells manufacturers, buyers and inspectors how these screws are defined, designated, marked and linked to the required material and surface-treatment standards.

What does SIST EN 4634:2009 specify?

SIST EN 4634:2009 specifies the characteristics of a particular aerospace screw type. It covers the screw form, the permitted dimensions and tolerances, the material, the surface treatment, the designation system, the marking and the technical specification used with the product.

The document is organized into these main clauses:

• Scope
• Normative references
• Required characteristics
• Designation
• Marking
• Technical specification

Clause 3 sets out the required characteristics, and it points to Figure 1 and Table 1 for the product geometry and size coding. The dimensions are given in millimetres and apply after surface treatment, which matters in practice because inspection must be done at the right stage of manufacture.

What are the key requirements of SIST EN 4634:2009?

SIST EN 4634:2009 defines the screw configuration through Figure 1 and Table 1. That means the head shape, recess, thread arrangement, dimensions, tolerances and mass are fixed for this fastener family, so the part can be ordered and checked against the same definition.

Dimensions and tolerances

SIST EN 4634:2009 states that dimensions and tolerances are in millimetres and apply after surface treatment. It also says that tolerances of form and position follow ISO 7913, with values in micrometres applying before surface treatment, and that sharp edges are to be removed within the stated range. In practice, manufacturers have to control machining, finishing and inspection in the right sequence.

Materials and surface treatment

SIST EN 4634:2009 ties the material to EN 2399, EN 3639 and TR 3775. It also requires passivation in accordance with EN 2516. For users, that means the screw is not just defined by shape - its base material and corrosion-related surface treatment are part of the specification.

Thread and recess definition

SIST EN 4634:2009 uses MJ threads and refers thread limit dimensions to ISO 5855-2 and lead and runout to ISO 3353-1. The six lobe recess is defined by EN 3911. This matters because thread fit and driver engagement are critical for assembly, torque transfer and interchangeability in aerospace hardware.

Designation

SIST EN 4634:2009 gives a designation format with a description block and an identity block. The example shows how the standard number, diameter code and length code are combined, and it also notes an optional code that may be inserted between the two blocks. This is what buyers and planners use to specify exactly which screw version is needed.

Marking and technical specification

SIST EN 4634:2009 links marking to EN 2424 and to the diameter code, using Table 2 and Figure 1. Clause 6 points to EN 2576 as the technical specification. In practice, marking supports identification and traceability, while the technical specification provides the companion requirements used with the screw standard.

What terms does SIST EN 4634:2009 define?

• FE-PA2601 (A286) - The heat resisting steel used for these screws.
• 100° countersunk head - A head shape that sits in a matching countersunk hole at a 100° angle.
• Six lobe recess - The internal drive recess used for the screwdriver or bit, defined by EN 3911.
• Short thread - A thread length form selected for this screw type rather than a fully threaded shank.
• Passivated - The screw receives a surface treatment specified by EN 2516 to support corrosion resistance.
• MJ threads - The aerospace metric thread form used by this screw standard.
• Designation - The coding system used to order and identify the screw variant.
• Technical specification - The companion document that sets the technical requirements used with the product standard.

Who uses SIST EN 4634:2009?

SIST EN 4634:2009 is used by aerospace fastener manufacturers, aircraft and equipment assemblers, purchasing teams and inspection or quality personnel. It is relevant wherever 100° countersunk, six lobe recess screws in heat resisting steel are specified for aerospace applications.

Designers use it to select the correct screw form and thread series. Buyers use it to order the right designation. Quality and inspection teams use it to verify dimensions, surface treatment, marking and conformance to the referenced standards.

Which standards are used with SIST EN 4634:2009?

• ISO 3353-1 - Gives requirements for lead and runout threads for rolled external threads.
• ISO 5855-2 - Provides limit dimensions for MJ bolts and nuts.
• ISO 7913 - Specifies tolerances of form and position for aerospace bolts and screws.
• EN 2399 - Covers heat resisting steel FE-PA2601 bars for forged bolts.
• EN 2424 - Sets marking for aerospace products.
• EN 2516 - Covers passivation of corrosion resisting steels and decontamination of nickel base alloys.
• EN 2576 - Gives the technical specification used with this screw standard.
• EN 3639 - Covers wire for forged fasteners in FE-PA2601.
• EN 3911 - Defines the six lobe recess geometry.
• TR 3775 - Provides materials guidance for bolts and pins.

What does the SIST EN 4634:2009 document contain?

SIST EN 4634:2009 contains a product definition figure, size tables, a designation example and a marking table. Figure 1 shows the screw geometry and identifies the recess, thread and marking location. Table 1 links thread designations to diameter and length codes, while Table 2 links marking style to diameter code.

The document also states where dimensions apply in the manufacturing sequence, and it points to the companion standards needed for threads, materials, surface treatment, recess geometry and marking. For engineering and quality work, this makes the standard a compact reference for specifying and checking the screw rather than a general fastener handbook.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aeronavtika - Vijaki, 100° ugrezna glava, šestzoba vdolbina, kratek navoj, iz toplotnoodpornega jekla FE-PA2601 (A286), pasivirani - Klasifikacija: 900 MPa (pri temperaturi okolice)/650 °CLuft- und Raumfahrt – 100° Senkschrauben, kurzes Gewinde, Sechs-Bogenzahn, aus hochwarmfester Stahl FE-PA2601 (A286), passiviert - Klasse: 900 MPa (bei Raumtemperatur)/650° CSérie aérospatiale - Vis, 100° à tête fraisée, à filetage court, à empreinte six lobes, en acier résistant à chaud FE-PA2601 (A286), passivées - Classification: 900 Mpa (à température ambiante)/650°CAerospace series - Screws, 100° countersunk head, six lobe recess, short thread, in heat resisting steel FE-PA2601 (A286), passivated - Classification: 900 MPa (at ambient temperature)/650 °C49.030.20Sorniki, vijaki, stebelni vijakiBolts, screws, studsICS:Ta slovenski standard je istoveten z:EN 4634:2009SIST EN 4634:2009en01-oktober-2009SIST EN 4634:2009SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 4634
July 2009 ICS 49.030.20 English Version
Aerospace series - Screws, 100° countersunk head, six lobe recess, short thread, in heat resisting steel FE-PA2601 (A286), passivated - Classification: 900 MPa (at ambient temperature) / 650 °C
Série aérospatiale - Vis, 100° à tête fraisée, à filetage court, à empreinte six lobes, en acier résistant à chaud FE-PA2601 (A286), passivées - Classification : 900 Mpa (à température ambiante) / 650 °C
Luft- und Raumfahrt – 100° Senkschrauben, kurzes Gewinde, Sechs-Bogenzahn, aus hochwarmfester Stahl FE-PA2601 (A286), passiviert - Klasse: 900 MPa (bei Raumtemperatur) / 650 °C This European Standard was approved by CEN on 12 March 2009.
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 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 Management Centre has the same status as the official versions.
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