SIST EN 3768:2012

• Abstract:

  This European Standard specifies the characteristics of one lug, reduced series, counterbored fixed anchor nuts, with a self locking feature achieved by forming the upper portion out of round, in heat resisting steel, MoS2 lubricated.; Classification: 1100 MPa )/315 °C

• Status: Published
• Publication Date: 05-Jul-2012
• ICS: 49.030.30 - Nuts
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 18-Jun-2012
• Due Date: 23-Aug-2012
• Completion Date: 06-Jul-2012
• Ref Project: EN 3768:2012 - Aerospace series - Nuts, anchor, self-locking, one lug, fixed, reduced series, with counterbore, in heat resisting steel, MoS2 lubricated - Classification: 1 100 MPa (at ambient temperature)/315 °C

• Refers: SIST EN ISO 14589:2002 - Blind rivets - Mechanical testing (ISO 14589:2000)
• Effective Date: 28-Jan-2026
• Refers: SIST EN 9100:2018 - Quality Management Systems - Requirements for Aviation, Space and Defense Organizations
• Effective Date: 28-Jan-2026
• Refers: SIST EN 9133:2018 - Aerospace series - Quality Management Systems - Qualification Procedure for Aerospace Standard Products
• Effective Date: 28-Jan-2026
• Refers: SIST EN ISO 15792-1:2008 - Welding consumables - Test methods - Part 1: Test methods for all-weld metal test specimens in steel, nickel and nickel alloys (ISO 15792-1:2000)
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2398:2008 - Aerospace series - Heat resisting steel FE-PA2601 (X6NiCrTiMoV26-15) - Rm = 900 MPa - Bars for machined bolts - D = 25 mm
• Effective Date: 28-Jan-2026
• Refers: SIST EN 2491:2011 - Aerospace series - Molybdenum disulphide dry lubricants - Coating methods
• 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 2424:2008 - Aerospace series - Marking of aerospace products
• Effective Date: 28-Jan-2026
• Refers: SIST EN 3638:2026 - Aerospace series - Heat resisting alloy X6NiCrTiMoV26-15 (1.4980) - Consumable electrode remelted - Solution treated and precipitation treated - Sheets, strips and plates - 0,5 mm ≤ a ≤ 10 mm
• Effective Date: 28-Jan-2026

SIST EN 3768:2012 is the SIST version of EN 3768:2012 for aerospace anchor nuts. It specifies the characteristics of one lug, reduced-series, counterbored fixed self-locking nuts in heat resisting steel, lubricated with MoS2, for classification 1 100 MPa at ambient temperature and 315 °C. The standard is used when these nuts have to be specified, made, marked and qualified under a common aerospace requirement.

What does SIST EN 3768:2012 specify?

SIST EN 3768:2012 covers a specific type of aerospace anchor nut: one lug, fixed, reduced series, with counterbore, and a self-locking feature achieved by forming the upper portion out-of-round. It sets the product characteristics and links them to a defined strength and temperature classification.

The document is organized into six clauses:

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

Clause 3 is the main technical section. It ties the nut to a figure and a table for its configuration, dimensions and mass, and it points to external standards for tolerances, materials, lubrication, marking and procurement rules. In practice, this means the nut is not defined only by a name - it is defined by drawing, material, surface treatment and identification rules.

What are the key requirements of SIST EN 3768:2012?

SIST EN 3768:2012 focuses on the geometry, the material, the surface treatment and the way the part is identified and qualified. The important point for users is that design, purchasing, inspection and approval all have to follow the same references.

Configuration, dimensions and tolerances

Clause 3.1 states that the configuration, dimensions and masses are given in Figure 1 and Table 1. Dimensions and tolerances conform to ISO 3191 and are expressed in millimetres before MoS2 lubrication, while form and position tolerances conform to ISO 8788. This matters because drawing review and inspection must use the pre-lubricated size and the stated geometric tolerances.

The self-locking zone is created by forming the upper portion out-of-round, and Figure 1 identifies the area where this applies. Tooling marks are permitted in that area. For manufacturing, this tells the supplier how the locking feature is created and where normal process marks are acceptable.

Materials and surface treatment

Clause 3.2 allows the nut material to be taken from EN 2398, EN 2399, EN 3638, EN 3639 or TR 3791. Clause 3.3 specifies EN 2491 for the surface treatment, with thickness not specified, and requires sharp edges to be removed within the stated edge-break range. In practice, buyers and quality teams need to confirm both the base material family and the coating system, not just the finished size.

Designation and marking

Clause 4 gives the designation format and shows an example based on the diameter code from Table 1. It also notes that, if needed, originator code 19005 is placed between the description block and the identity block. Clause 5 requires marking according to EN 2424, style N, with the marking location shown in Figure 1. This is what allows the part to be ordered and traced consistently.

Technical specification

Clause 6 points to ISO 5858 as the general technical specification, with two exceptions: manufacturer approval follows EN 9100 and product qualification follows EN 9133. For suppliers, this links the part to aerospace quality management and qualification practices.

What terms does SIST EN 3768:2012 define?

• Anchor nut - A nut designed to be fixed in position on a structure, used here in a one-lug, fixed form.
• Self-locking - A locking action created by the out-of-round upper portion, so the nut resists loosening.
• Reduced series - A compact nut series with a reduced configuration compared with a standard series.
• Counterbore - A cylindrical recess in the nut body used to suit the assembly geometry.
• MoS2 - Molybdenum disulphide dry lubricant used as the surface treatment.
• MJ threads - Aerospace metric threads referenced by ISO 3191 and ISO 5855-2.

Who uses SIST EN 3768:2012?

SIST EN 3768:2012 is used by aerospace and defence manufacturers, fastener suppliers, design engineers, purchasing teams and quality departments. They use it to specify the nut on drawings, select acceptable materials, apply the correct lubricant coating, inspect dimensions and identify the part for production or qualification. It is also relevant to organizations working under aerospace quality management and product qualification requirements.

Which standards are used with SIST EN 3768:2012?

• EN 2398 and EN 2399 - heat resisting steel bar materials for machined or forged bolts, used here as material options.
• EN 2424 - marking of aerospace products, used for the required marking style.
• EN 2491 - molybdenum disulphide dry lubricants, used for the surface treatment.
• EN 3638 and EN 3639 - additional heat resisting steel material references listed for this nut.
• EN 9100 - quality management requirements for aviation, space and defence organizations, used for manufacturer approval.
• EN 9133 - qualification procedure for aerospace standard parts, used for product qualification.
• TR 3791 - materials for all metal self-locking nuts and thin wall inserts, listed as a material reference.
• ISO 3191 - dimensions for the related anchor nut family.
• ISO 5855-2 - MJ thread limit dimensions for bolts and nuts.
• ISO 5858 - general procurement specification for self-locking nuts.
• ISO 8788 - tolerances of form and position for metric nuts.

What does the SIST EN 3768:2012 document contain?

SIST EN 3768:2012 contains one figure and one table that define the nut’s configuration, reference dimensions, mass and marking location. The technical body then adds the designation format, the marking rule and the procurement and qualification route. For users, the document serves as a concise product definition for design, manufacture, inspection and aerospace purchasing.

SLOVENSKI STANDARD
01-september-2012
Aeronavtika - Zakovne matice, samovarovalne, enostranske, iz jekla, kadmirane,
mazane z MoS2 - Klasifikacija: 1100 MPa (pri temperaturi okolice)/315 °C
Aerospace series - Nuts, anchor, self-locking, one lug, fixed, reduced series, with
counterbore, in heat resisting steel, MoS2 lubricated - Classification: 1 100 MPa (at
ambient temperature)/315 °C
Luft- und Raumfahrt - Annietmuttern, selbstsichernd, einseitiger verkürzter Flansch, mit
zylindrischer Aussenkung, aus hochwarmfestem Stahl, MoS2-geschmiert - Klasse: 1 100
MPa (bei Raumtemperatur)/315 °C
Série aérospatiale - Écrous à river, à freinage interne, fixes, simple patte, série réduite,
avec chambrage, en acier résistant à chaud, lubrifiés MoS2 - Classification: 1 100 MPa
(à température ambiante)/315 °C
Ta slovenski standard je istoveten z: EN 3768:2012
ICS:
49.030.30 Matice Nuts
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 3768
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2012
ICS 49.030.30
English Version
Aerospace series - Nuts, anchor, self-locking, one lug, fixed,
reduced series, with counterbore, in heat resisting steel, MoS2
lubricated - Classification: 1 100 MPa (at ambient
temperature)/315 °C
Série aérospatiale - Écrous à river, à freinage interne, fixes, Luft- und Raumfahrt - Annietmuttern, selbstsichernd,
simple patte, série réduite, avec chambrage, en acier einseitiger verkürzter Flansch, mit zylindrischer
résistant à chaud, lubrifiés MoS2 - Classification: 1 100 Aussenkung, aus hochwarmfestem Stahl, MoS2-
MPa (à température ambiante)/315 °C geschmiert - Klasse: 1 100 MPa (bei Raumtemperatur)/315
°C
This European Standard was approved by CEN on 23 December 2011.

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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 3768:2012: E
worldwide for CEN national Members.

Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Required characteristics .5
3.1 Configuration — Dimensions — Masses .5
3.2 Materials .5
3.3 Surface treatment .5
4 Designation .7
5 Marking .7
6 Technical specification .7

Foreword
This document (EN 3768:2012) has been prepared by the Aerospace and Defence Industries Association of
Europe - Standardization (ASD-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 ASD,
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 2012, and conflicting national standards shall be
withdrawn at the latest by September 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. C
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