Author: [Bruce Zhou]
Affiliation: [Jota Machinery Composites Material Prepreg Solution]
Corresponding Author: [jotamachinery@gmail.com]
Published : April 08 , 2026
Abstract
Hydrogen transport is forcing a reassessment of conventional pipeline design. Steel systems, long considered the default solution for oil and gas transmission, show clear limitations when exposed to hydrogen, including embrittlement, crack propagation, and accelerated service life reduction. Reinforced thermoplastic pipe (RTP), originally developed for corrosive hydrocarbon service, is now being evaluated as a viable alternative for hydrogen pipelines due to its corrosion resistance, flexibility, and spoolable installation advantages.
However, RTP should not be treated as a direct material replacement for steel. Its behavior is governed by composite mechanics, where fibre architecture, reinforcement thickness, and interface behavior define structural performance. This paper examines RTP as a composite pressure system designed for hydrogen service, focusing on the relationship between fibre orientation, wall thickness, and pressure capacity. The analysis shows that fibre winding angle has a stronger influence on performance than material selection alone, with ±45° configurations providing significantly higher pressure resistance than traditional 0/90° layouts.
At the same time, key engineering gaps remain unresolved, particularly hydrogen permeation, fatigue under cyclic pressure, temperature-dependent creep, and installation-induced stresses. The paper concludes that RTP is suitable for specific hydrogen transport scenarios, especially short- to medium-distance pipelines and flexible systems, but requires further development before it can replace steel in high-pressure, long-distance offshore applications.
Keywords
reinforced thermoplastic pipe hydrogen, RTP hydrogen pipeline, composite hydrogen pipeline, spoolable hydrogen pipe, non-metallic hydrogen pipeline, fibre orientation RTP, hydrogen pipeline design composite
1. Introduction
Hydrogen is not a new fuel, but it is being used in a new way. The current push toward large-scale hydrogen transport is exposing weaknesses in pipeline systems that were originally designed for natural gas and crude oil.
Steel pipelines, which have performed reliably for decades, behave differently in hydrogen service. The problem is not corrosion in the traditional sense. It is embrittlement. Hydrogen diffuses into the metal, weakens the microstructure, and accelerates crack growth. In high-pressure systems, this creates a failure mode that is both sudden and difficult to predict.
At the same time, hydrogen introduces operational challenges that go beyond material compatibility. Its low volumetric energy density requires higher flow velocities and significantly higher compression energy. In practical terms, this means more aggressive operating conditions, higher fatigue demand, and increased energy consumption.
This is where reinforced thermoplastic pipe enters the discussion. RTP was not developed for hydrogen. It was developed to solve corrosion problems in oilfield pipelines. But its properties—chemical resistance, flexibility, low weight, and spoolability—make it a natural candidate for hydrogen transport.
The question is not whether RTP can carry hydrogen.
The question is whether it can do so without introducing new risks.
2. Literature Review
2.1 Hydrogen vs Steel Pipelines
Hydrogen affects steel differently than methane. Its small molecular size allows it to diffuse into the material, where it reduces ductility and promotes brittle fracture. Studies have shown service life reductions of 20–50% under hydrogen exposure.
For offshore applications, this is not a marginal issue. It is a critical risk. A brittle failure in a high-pressure subsea pipeline is not gradual. It is catastrophic.
2.2 RTP as an Alternative Pipeline System
RTP offers a different failure philosophy. Instead of brittle fracture, it exhibits ductile and progressive behavior. Its thermoplastic liner provides a chemical barrier, while fibre reinforcement carries the structural load.
Key advantages include:
- No internal corrosion
- High flexibility for installation and seabed movement
- Low surface roughness (stable flow characteristics)
- Low density, reducing installation cost
- Fusion joints, minimizing leak paths
These properties make RTP particularly attractive for hydrogen service, where corrosion and leakage are major concerns.
2.3 Composite Pipeline Design Principles
Unlike steel pipelines, RTP does not rely on homogeneous material strength. It is a layered composite system where each component plays a specific role:
- Thermoplastic liner → sealing and chemical resistance
- Fibre reinforcement → load-bearing structure
- Outer layer → environmental protection
This separation of function is critical. It means that performance is driven primarily by reinforcement design, not by the polymer itself.
3. Methodology
The analysis is based on a combined experimental and numerical approach applied to a DN80 RTP configuration.
Material characterization included tensile testing of HDPE and glass fibre reinforcement using standard methods. These results were used to define material properties for finite element analysis.
The structural model was validated against analytical solutions for orthotropic cylinders. Once validated, a parametric study was carried out to evaluate the effect of:
- Fibre orientation (0/90°, ±45°, ±30°)
- Reinforcement thickness (1.1 mm, 2.2 mm, 3.3 mm)
- Internal pressure (2–10 MPa)
The failure condition was defined using maximum principal stress, with a utilization ratio limit of approximately 77% to maintain a safety margin.
4. Results
4.1 Reinforcement Carries the Load
The results confirm that internal pressure is almost entirely carried by the fibre layer. The HDPE liner contributes minimally to structural strength. Its role is primarily sealing and chemical resistance.
This reinforces a key design rule:
RTP is a fibre-driven structure, not a plastic pipe.
4.2 Fibre Orientation Dominates Performance
The most significant finding is the impact of fibre angle.
At the same thickness:
- ±45° configuration → ~8 MPa capacity
- 0/90° configuration → ~6 MPa capacity
This represents a substantial performance difference without increasing material usage.
The reason lies in load distribution. Pressure in cylindrical structures creates combined stress states. ±45° orientation allows better shear transfer and strain compatibility, while 0/90° configurations are less efficient under multi-axial loading.
4.3 Thickness Provides Linear Improvement
Increasing reinforcement thickness increases pressure capacity in a predictable way. However, this comes with higher material cost and weight.
From a cost-performance standpoint, optimizing fibre orientation provides a more efficient solution than simply increasing thickness.
5. Discussion
5.1 Hydrogen Transport Changes Design Priorities
In hydrogen pipelines, strength is not the only concern. Permeation, fatigue, and energy efficiency become equally important.
The study shows that structural design can be optimized effectively, but it also highlights gaps that cannot be ignored.
5.2 Key Engineering Gaps
Several critical issues remain unresolved:
- Hydrogen permeation through HDPE
- Fatigue under cyclic pressure
- Temperature-dependent creep behavior
- Installation stresses during reel-lay
In offshore applications, these factors often govern design more than pressure capacity.
5.3 Where RTP Works Best
Based on current understanding, RTP is well suited for:
- Flowlines and gathering systems
- Hydrogen distribution networks
- Flexible pipeline applications
- Onshore and shallow-water systems
It is less suitable for:
- Ultra-deepwater risers
- High-temperature environments
- Long-distance high-pressure transmission
6. Conclusion
Hydrogen transport is exposing the limits of traditional pipeline design. Steel pipelines face material-related challenges, while RTP introduces a different set of design considerations.
The main lesson is clear:
RTP is not limited by material strength. It is controlled by fibre architecture.
Fibre orientation and reinforcement design determine performance more than the thermoplastic liner itself. This shifts the engineering focus from material selection to structural configuration.
At the same time, unresolved issues such as permeation, fatigue, and creep must be addressed before RTP can be widely adopted in offshore hydrogen transport.
For now, RTP provides a strong solution for specific applications. But its full potential will depend on how well these remaining challenges are managed.
References
- Le, T. D. Design of Reinforced Thermoplastic Pipelines for Transport of Hydrogen, Griffith University, 2023
- Olabisi, O. et al. Reinforced Thermoplastic Pipe for Oil and Gas, Saudi Aramco Journal, 2003
- Okolie, M. A. et al. Manufacturing Defects in Thermoplastic Composite Pipes, Applied Composite Materials, 2023