EN 4185:2001

Overview

EN 4185:2001 is a European standard developed by CEN that specifies the requirements for aerospace-grade pipe couplings, specifically the tee bulkhead on run long type, made from titanium alloy. This standard covers components with an 8°30' pipe coupling angle, designed for use in aerospace fluid systems. It ensures high performance under demanding conditions, such as nominal pressures up to 28,000 kPa and operating temperatures ranging from -55 °C to 135 °C.

This standard is crucial for manufacturers and engineers working on aerospace fluid systems requiring reliable, lightweight, and corrosion-resistant pipe coupling solutions.

Key Topics

• Scope and Purpose
  EN 4185:2001 defines the physical and technical characteristics of titanium alloy tee bulkhead pipe couplings used in aerospace applications. It provides detailed specifications on dimensions, materials, surface treatments, and installation to ensure compatibility and performance.

• Material Specifications
  The tees must be manufactured from titanium alloys compliant with standards EN 3311, EN 3312, EN 3314, or EN 3315 to guarantee strength, corrosion resistance, and durability suitable for aerospace environments.

• Design and Dimensions
  The standard sets out precise dimensional criteria for tee bulkheads, including thread sizes (based on ISO 5855-3), surface roughness, and internal finishing. These details help ensure leak-tight connections and ease of assembly.

• Surface Treatment and Lubrication
  Prior to lubrication (according to EN 2491), the component surfaces require abrasive blasting with non-metallic grit to create optimal adhesion. Lubrication films must maintain thickness between 0.005 mm to 0.013 mm on threads and seals.

• Pressure and Temperature Ratings
  Rated for nominal pressures up to 28,000 kPa and temperature operating ranges between -55 °C and 135 °C, these fittings are designed to meet the stringent demands of aerospace fluid systems.

• Marking and Traceability
  The standard mandates marking in line with EN 2424 guidelines to ensure traceability and verification of conformity.

Applications

• Aerospace Fluid Systems
  EN 4185:2001 covers titanium alloy tees used in critical aerospace fluid infrastructures, including hydraulic, fuel, and cooling systems where high strength-to-weight ratio and resistance to corrosion and extreme temperatures are paramount.

• Bulkhead Penetrations
  The long tee bulkhead on run configuration facilitates secure and leak-proof pipe passage through bulkheads in aircraft, spacecraft, and related aerospace vehicles.

• High-Pressure Environments
  With a nominal pressure capability up to 28 MPa (28,000 kPa), these components serve in high-pressure pipelines within aerospace assemblies.

• Precision Engineering and Maintenance
  The detailed technical specifications ensure that manufacturers and maintenance personnel can consistently produce, inspect, and replace these fittings with reliable interchangeability and performance.

Related Standards

EN 4185:2001 references and works in conjunction with several related aerospace standards to ensure comprehensive compliance and interoperability:

• ISO 5855-3 – Limit dimensions for aerospace MJ thread fittings.
• EN 2424 – Marking of aerospace products for traceability.
• EN 2491 – Coating methods for molybdenum disulphide dry lubricants.
• EN 3267 – Washers for bulkhead fittings in titanium alloys.
• EN 3274 – Geometric configuration for pipe coupling threads.
• EN 3275 – Technical specifications for pipe coupling dynamic beam seals.
• EN 3311, EN 3312, EN 3314, EN 3315 – Specifications for titanium alloy bars and forgings used in aerospace fittings.

Using EN 4185:2001 in combination with these standards provides a robust framework for designing, manufacturing, and maintaining titanium alloy pipe couplings suitable for the aerospace industry's highest safety and quality standards.

Adopting EN 4185:2001 helps aerospace manufacturers ensure optimal performance, safety, and longevity of fluid system components, contributing to the reliability of aerospace vehicles operating under extreme conditions. This standard is an essential reference for engineering, procurement, and quality assurance professionals involved in aerospace fluid system design and maintenance.