Overview
ISO/TR 13086-4:2019 is a Technical Report from ISO that provides guidance on cyclic fatigue for components of composite gas cylinders. Part 4 focuses on fatigue behaviour of structural reinforcing fibres (glass, carbon, aramid and hybrids) and of structural and non‑structural liners (metal and polymeric) used in composite pressure vessels. This document is guidance (basic level of understanding) rather than a set of normative requirements, and supports safe, fatigue‑aware design and evaluation of composite cylinders used across transport, vehicle fuel, and stationary applications.
Key Topics
- Service conditions: effects of temperature (typical −40 °C to +85 °C), moisture and environmental exposure on fatigue and material properties.
- Pressure regimes and cycles: working pressures from low‑pressure liquified gas (~5–20 bar) up to high‑pressure compressed gas (to ~1 100 bar); test pressures typically 125–167 % of rated working pressure; examples of qualification cycle counts (e.g., 12 000 or 24 000 cycles for non‑limited life, 250/500 cycles per year for limited life).
- Material fatigue properties: behaviour and data needs for fibres, liners (steel, aluminium, HDPE, polyamide), and resins; hybrid reinforcement issues.
- Composite/liner interaction: load sharing, localized strain differences, weld effects, and how liner compression (e.g., polymer liners) influences fatigue life.
- Design and analysis considerations: autofrettage benefits, analysis methods, Leak‑Before‑Burst (LBB) concepts, damage‑tolerance, aging and environmental degradation, cycle counting and combining varied load spectra, and qualification testing guidance.
Applications
ISO/TR 13086-4:2019 is directly applicable for:
- Design and risk assessment of composite gas cylinders (transportable cylinders, vehicle fuel tanks, stationary pressure vessels and refuelling cascades).
- Engineers developing cylinder material specifications, fatigue test programs and qualification regimes.
- Manufacturers and testing laboratories planning fatigue and lifecycle evaluations (qualification testing, LBB and damage‑tolerance analysis).
- Safety and standards professionals comparing service profiles (full vs partial cycles, fleet vs private use) and setting life limits.
Who Should Use This Standard
- Mechanical and composite design engineers working on high‑pressure gas storage systems.
- Materials scientists characterizing fibre/liner fatigue properties.
- Regulatory bodies and certification organizations specifying qualification tests and service limits.
- Asset owners/operators assessing maintenance, inspection intervals and end‑of‑life criteria.
Related Standards
- The ISO 13086 series (other parts cover broader composite cylinder design topics).
- ISO 10286 for gas cylinder terminology and related definitions.
Keywords: ISO/TR 13086-4:2019, composite cylinders, cyclic fatigue, fibres, liners, gas cylinders, autofrettage, leak before burst, qualification testing, pressure cycles.