Flexyshell Concept

 

A New Approach to Pressure Vessels

Flexyshell is a novel high-pressure storage system designed for hydrogen and other gases, but its principles extend to any pressurized container, buoyancy modules, or modular structural shells. Unlike conventional steel tanks or composite overwrapped pressure vessels (COPVs), Flexyshell separates how stresses are managed within the vessel, creating a predictable, lightweight, and versatile architecture.

Flexible Wall + External Tendons

At the heart of Flexyshell is a simple idea: let the cylindrical wall handle hoop stress and let a network of external tendons handle longitudinal loads. Unlike rigid shells, the wall is intentionally flexible — it can micro-deform and slightly elongate under pressure. This small, controlled movement allows the tendons to engage fully and carry all axial loads. The proprietary end architecture  transfers axial loads through to tension elements. The flexibility of the wall is what makes this clean separation of forces possible, eliminating the stress conflicts that make traditional composites brittle and difficult to scale. The flexible wall distributes pressure evenly, absorbs local deformation elastically, and can be made from materials ranging from cost-effective steel-reinforced HDPE for stationary storage to high-performance fibers like aramid or carbon for mobile applications..

Modular, Scalable, and Safe

Flexyshell modules can be nested, replaced, or combined in series to create high-pressure systems or structural platforms. The “tank-in-tank” concept provides multi-stage containment: a failure in an inner vessel releases pressure only into the next shell, not the environment, enabling safer, controlled depressurization.

This modularity is possible because the vessel can be dismantled — something impractical in conventional composite tanks. In Flexyshell, the axial load is carried entirely by the tendons, leaving the connection interface between the cylindrical and hemispherical parts  free from immense longitudinal forces. This makes it feasible to assemble, inspect, or replace individual shells without compromising strength or sealing integrity. The external tendon lattice also acts as a built-in safety mesh, catching debris in case of the shell failure and maintaining structural integrity even under extreme off-nominal loads.

Pressure as a Structural Tool

Internal gas pressure is not just stored energy—it stiffens the structure. The flexible wall carries hoop tension, while the tendon system channels axial and external loads, allowing the module to resist bending and deformation. This principle works for hydrogen storage, floating marine platforms, or any application requiring lightweight, high-strength pressurized structures.

Advantages at a Glance

 

  • Predictable Mechanics: Hoop and axial stresses are fully decoupled and carried by uniform materials with well-defined properties (unlike composite overwrapped pressure vessels). This allows the vessel’s behavior to be accurately modeled and calculated from first principles, greatly reducing dependence on empirical testing..
  • Material Selection Flexibility: A wide range of materials — steel, aramid, carbon fiber, or polymer liners — can be used according to specific application needs.
  • Recyclable: Unlike conventional COPVs that must be scrapped as waste, Flexyshell modules are built from thermoplastic and separable parts that can be fully recycled and reused.
  • Lightweight and Efficient: Optimized material allocation improves volumetric and gravimetric efficiency.
  • Scalable Architecture:
    Multiple cylindrical sections can be joined end-to-end to build vessels of virtually any required length, using the same end architecture and BOP interfaces—only tendon length or quantity changes. Because these two components (membrane sections and tendons) are the simplest and lowest-cost parts, a vessel with twice the storage capacity costs far less than twice as much.
    Moreover, long Flexyshell vessels can be assembled directly on site, avoiding the impracticality of transporting or lifting 50- to 100-metre-long rigid tanks. Sections are joined, tendons put in place, the vessel is pressurised—and it’s ready for service.
  • Modular and Serviceable: Components can be replaced or upgraded individually, extending operational life.
  • Integrated Safety: Tendon networks and optional outer shells provide staged containment and fail-safe behavior.

 

Designed for Multiple Applications

Whether for stationary hydrogen storage, mobile energy systems, or floating platforms, Flexyshell provides a unified structural solution. By separating stress pathways and embracing flexible, modular components, it offers an inherently safer, lighter, and more cost-effective alternative to traditional pressure vessel designs.