EN 4031:2001

Aerospace series - Pipe coupling 8°30' in titanium alloy - Nut for welded ferrule

This standard specifies the characteristics of nuts for welded ferrules, for pipe couplings 8 30', in titanium alloy, for
aerospace applications.
Nominal pressure: up to 28 000 kPa
Temperature range:   55  C to 135  C

Luft- und Raumfahrt - Rohrverschraubung 8°30' aus Titanlegierung - Mutter für Anschweißstutzen

Diese Norm legt die Eigenschaften von Muttern für Anschweißstutzen, für Rohrverschraubungen 8 30', aus Titanlegierung,
zur Verwendung in der Luft- und Raumfahrt fest.
Nenndruck: bis 28 000 kPa
Temperaturbereich:   55  C bis 135  C

Série aérospatiale - Système de raccordement 8°30' en alliage de titane - Écrou pour olive soudée

La présente norme spécifie les caractéristiques d'écrous pour olive à souder, pour les systèmes de raccordement 8 30',
en alliage de titane, pour applications aérospatiales.
Pression nominale: jusqu'à 28 000 kPa
Plage de température:   55  C à 135  C

Aerospace series - Pipe coupling 8-30' in titanium alloy - Nut for welded ferrule

General Information

• Status: Published
• Publication Date: 18-Sep-2001
• Withdrawal Date: 30-Mar-2002
• ICS: 49.080 - Aerospace fluid systems and components
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 3 - Mechanical
• Current Stage: 9093 - Decision to confirm - Review Enquiry
• Start Date: 31-May-2017
• Completion Date: 14-Apr-2025
• Ref Project: SIST EN 4031:2002 - Aerospace series - Pipe coupling 8°30' in titanium alloy - Nut for welded ferrule

Overview

EN 4031:2001 is a European standard developed by the Comité Européen de Normalisation (CEN) specifically for aerospace applications. It defines the characteristics and requirements for nuts used in welded ferrules of pipe couplings with an 8°30' angle, made from titanium alloy. These precise specifications ensure reliable performance under demanding aerospace operating conditions.

Designed to withstand a nominal pressure of up to 28,000 kPa and operate within a temperature range of -55 °C to 135 °C, EN 4031:2001 ensures the durability, safety, and compatibility of pipe coupling components used in aerospace fluid systems.

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Key Topics

• Material Specifications
  Nuts must be manufactured from titanium alloy compliant with EN 3311 or EN 3314, ensuring high strength-to-weight ratio and corrosion resistance essential for aerospace environments.

• Dimensional Requirements
  Detailed dimensions and tolerances, including thread sizes and minor diameters, are defined to ensure precision fit and secure connections. The standard includes specific measurements for various nominal pipe diameters.

• Surface Treatment and Lubrication
  Surface finish requirements include precise roughness parameters. Before lubricant application, surfaces must be dry abrasive blasted using non-metallic grit per EN 2497. A PTFE-based coating (e.g., Tegliss 31) is specified for lubrication, minimizing friction (coefficient of friction ≤ 0.12) and enhancing wear resistance.

• Marking and Identification
  Nuts must be marked according to EN 2424, enabling traceability and quality assurance. Markings are applied on designated areas as per the standard.

• Performance Characteristics
  The standard details mechanical and hydraulic performance expectations, including pressure resistance, temperature endurance, and fluid compatibility. Lubricated nuts must withstand repeated assemblies without degradation.

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Applications

EN 4031:2001 applies primarily to the aerospace industry, where reliable fluid and gas transfer systems are critical. Typical applications include:

• Hydraulic and fuel line connections on aircraft
• High-pressure fluid systems in aerospace vehicles
• Welded pipe coupling assemblies requiring lightweight yet strong components
• Maintenance and replacement parts ensuring consistent quality and safety standards

The use of titanium alloy offers benefits such as corrosion resistance, light weight, and mechanical strength, making components compliant with EN 4031 ideal for harsh aerospace environments.

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Related Standards

EN 4031:2001 integrates and references several related European and International standards to form a comprehensive framework for aerospace pipe couplings:

• ISO 5855-3: Limits for MJ threads used in aerospace fluid system fittings
• ISO 8788: Tolerances on aerospace nuts regarding form and position
• EN 2424: Marking requirements for aerospace products ensuring traceability
• EN 2497: Dry abrasive blasting procedures for titanium and its alloys
• EN 3275: Technical specifications for pipe couplings with dynamic beam seals
• EN 3311 / EN 3314: Specifications for titanium alloy grades used in manufacturing these nuts

Together, these interconnected standards support quality control, interoperability, and safety in aerospace fluid system components.

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Keywords: aerospace pipe couplings, titanium alloy nuts, welded ferrule nuts, EN 4031, aerospace fluid systems, high-pressure pipe fittings, PTFE coating, titanium pipe coupling standard, aerospace hydraulic fittings, European aerospace standards.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aerospace series - Pipe coupling 8-30' in titanium alloy - Nut for welded ferruleLuft- und Raumfahrt - Rohrverschraubung 8°30' aus Titanlegierung - Mutter für AnschweißstutzenSérie aérospatiale - Systeme de raccordement 8°30' en alliage de titane - Écrou pour olive soudéeAerospace series - Pipe coupling 8°30' in titanium alloy - Nut for welded ferrule49.080Aerospace fluid systems and componentsICS:Ta slovenski standard je istoveten z:EN 4031:2001SIST EN 4031:2002en01-januar-2002SIST EN 4031:2002SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 4031September 2001ICS 49.080English versionAerospace series - Pipe coupling 8°30' in titanium alloy - Nut forwelded ferruleSérie aérospatiale - Système de raccordement 8°30' enalliage de titane - Ecrou pour olive soudéeLuft- und Raumfahrt - Rohrverschraubung 8°30' ausTitanlegierung - Mutter für AnschweißstutzenThis European Standard was approved by CEN on 29 December 2000.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the 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 translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2001 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 4031:2001 ESIST EN 4031:2002

ScopeThis standard specifies the characteristics of nuts for welded ferrules, for pipe couplings 8°30', in titanium alloy, foraerospace applications.Nominal pressure: up to 28 000 kPaTemperature range:
55 °C to 135 °C2
Normative referencesThis European Standard incorporates by dated or undated reference provisions from other publications. These normativereferences are cited at the appropriate places in the text and the publications are listed hereafter. Fo
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