SIST EN 4189:2004

Overview

SIST EN 4189:2004 is a European standard developed by CEN, specifying the characteristics of long bulkhead branch tees for pipe couplings with an 8°30' angle, made from titanium alloy. This standard targets aerospace applications where high performance, durability, and resistance to extreme conditions are critical. It defines requirements for nominal pressures up to 28,000 kPa and operating temperatures ranging from -55 °C to 135 °C.

This document is vital for manufacturers and engineers designing and producing aerospace fluid systems, ensuring compatibility, safety, and reliability through consistent specifications on dimensions, materials, surface treatments, and installation.

Key Topics

• Pipe Coupling Specification
  The standard covers tees designed specifically for the 8°30' pipe coupling in titanium alloy. Precision in dimensions and thread specifications is mandated to ensure secure and leak-proof fluid connections within aerospace systems.

• Material Requirements
  Titanium alloy grades reference EN 3311, EN 3312, EN 3314, and EN 3315, emphasizing high strength, corrosion resistance, and lightweight characteristics essential for aerospace fluid system components.

• Surface Treatment & Finishing
  Threads and sealing faces require lubrication per EN 2491, with a controlled film thickness between 0.005 mm and 0.013 mm following abrasive blasting with non-metallic grit. Internal surfaces must have a defined radius (R) between 0.3 mm and 1.0 mm and a surface roughness of 0.8 µm to ensure sealing integrity and mechanical performance without hand deburring.

• Design Dimensions and Mass
  Detailed dimensional tables specify various thread sizes, lengths, and mass per piece. These ensure standardization for ease of maintenance and compatibility in aerospace piping systems.

• Installation and Marking
  Bulkhead branch tees must follow installation instructions specifying proper washer use and thread engagement to maintain system integrity. Marking requirements adhere to EN 2424 to ensure clear identification of parts across their lifecycle.

Applications

• Aerospace Fluid Systems
  The primary application of SIST EN 4189:2004 is for high-pressure fluid systems in aerospace environments, including hydraulic, fuel, and pneumatic lines where high strength and corrosion resistance titanium alloys are necessary.

• Spacecraft and Aircraft Components
  These pipe coupling tees facilitate fluid routing through bulkhead components, maintaining pressure containment and preventing leakage in critical aerospace systems.

• High-Pressure and Temperature Systems
  With a nominal pressure rating up to 28,000 kPa and tolerance to temperatures from -55 °C to 135 °C, these tees are suitable for demanding aerospace conditions including extreme altitudes and variable climates.

Related Standards

• EN 2424: Aerospace Product Marking
  Defines marking conventions used to identify aerospace products, ensuring traceability and compliance.

• EN 2491: Molybdenum Disulphide Dry Lubricants
  Specifies coatings and lubrication methods applicable to the thread and sealing surfaces of the tees.

• EN 3274 & EN 3275: Pipe Coupling Geometry & Seal Specifications
  Detail geometric configurations and sealing technical specifications for 8°30' pipe couplings relevant to this standard.

• ISO 5855-3: Aerospace Threads
  Provides limits and dimensions for MJ thread fittings used in aerospace fluid systems, referenced within EN 4189.

• EN 3311 - EN 3315: Titanium Alloy Specifications
  Define the chemical and mechanical properties of titanium alloys used for manufacturing pipe coupling components.

By adhering to SIST EN 4189:2004, aerospace manufacturers ensure that pipe coupling tees made from titanium alloys meet stringent requirements for safety, compatibility, and performance within high-pressure and temperature aerospace fluid systems. This standard supports the design, production, and maintenance of critical components essential to modern aerospace engineering.