High Pressure Storage

Hydrogen systems are pushing pressure limits — from 350 bar to 700 bar and beyond — yet traditional composite tanks (COPVs) are running into fundamental material and safety barriers.
Flexyshell takes a completely different path: it stores pressure through tension, not rigidity

The Flexyshell Principle

Unlike conventional composite tanks that force one brittle wall to resist all loads at once, Flexyshell divides the job cleanly:

  • The flexible cylindrical wall carries only the round (hoop) pressure stress.

  • A network of external tendons carries the lengthwise (axial) loads between  end dome systems.

This clear separation prevents the stress conflicts that make conventional composite overwraps brittle and unpredictable.
The wall’s micro-flexibility allows it to stretch slightly under pressure, ensuring the tendons pick up the full axial load evenly.
The result: a lighter, stronger, and far more damage-tolerant structure.

Building Up to 1000 Bar  Safely (Multistage “Tank-in-Tank” Containment)

Flexyshell modules can be built as nested pressure shells—a “tank within a tank.”
Each flexible shell carries only part of the total load.
For example, instead of one brittle vessel trying to hold 900 bar directly, three concentric shells can each handle about 300 bar.

That achieves the same overall pressure difference (900 bar from the core to the outside world) but without exposing any single wall to the full stress.

Each shell is separated by a small annular gap that can be filled with gas at an intermediate pressure.
If one shell fails, pressure vents only into the next layer rather than to the atmosphere.
That means no shockwave, no uncontrolled hydrogen jet, and no flying debris—just a controlled equalization into the next stage.
The outermost shell can even be filled with nitrogen or another inert gas, acting as a safety buffer.

Safety by Design (Why Flexyshell Eliminates the Failure Modes of Conventional COPVs)

Flexyshell doesn’t merely make rupture less likely — it makes catastrophic failure physically improbable.

Reduction of Catastrophic Failure Modes

  • The flexible membrane shell tolerates local deformation and minor wrinkling under transient loads, preventing stress spikes that trigger brittle bursts in rigid composites.

  • The external tendon lattice carries longitudinal loads separately from hoop stresses, removing a primary cause of explosive burst events.

Intrinsic Overload Tolerance

  • Elastic redistribution of stress prevents local overstressing.

  • Multiple axial tendons provide redundancy — even if one fails, the rest maintain end-domes restraint and structural integrity.

Controlled Fragmentation and Debris Containment

  • The tendon mesh and domesystems hold the system together even if a wall breaches, trapping debris and preventing the explosive disintegration typical of COPV rupture.

  • Unlike a brittle composite overwrap — which stores concentrated elastic energy in a monolithic, high-stiffness shell that can be released suddenly as fragment kinetic energy — Flexyshell’s flexible membrane/tendon architecture does not provide the same reservoir of suddenly-releasable elastic energy. Its compliant membrane, redundant tendons, and staged venting either dissipate energy or contain fragments, so catastrophic fragment-launching bursts are effectively prevented..

Leak Resistance and Crack Arrest

  • Uniform hoop reinforcement and wrinkle-tolerant membranes prevent crack propagation.

  • Local buckling absorbs energy rather than transmitting it through the wall.

Fire and Thermal Event Resilience

  • Load paths are decoupled from the containment wall, so fire-protective layers can be added without distorting stress paths.

  • Conventional composite tanks soften and collapse abruptly once resin degrades; Flexyshell maintains cohesion.

Rapid Decompression and Venting Control

  • The system supports multi-path venting and surge-smoothing rather than relying on a single burst disk, cutting the risk of jet ignition and blow-off.

Predictable Degradation and Maintainability

  • Every major component — tendon loops, flexible wall, end dome systems — is inspectable and replaceable.

  • Unlike rigid tanks that must be scrapped after any suspected damage, Flexyshell modules can be repaired and safely returned to service.

Multistaging and Safety Shell Integration

  • Multi-layer containment (inner shell, secondary liner, external tendons, optional outer safety shell) ensures gradual, contained failure, not a blast.

  • Such layered architecture is impossible in monolithic composite designs. 

In short: Flexyshell fails slowly, locally, and controllably, never explosively.

 

Chain-Reaction Risk

A single COPV rupture can turn a storage yard into a fireball, as debris punctures nearby tanks and cascades the failure.
Flexyshell architecture breaks this chain entirely.
Each module is self-contained, and the tendon lattice doubles as a built-in debris net, so even a ruptured wall cannot project shrapnel into adjacent vessels.

 

Material Flexibility and Manufacturing Advantages

  • Stationary Systems: cost-effective HDPE or thermoplastic composite walls with steel cable tendons.

  • Mobile Systems: lightweight aramid or carbon tendons for vehicles, aircraft, or aerospace.

  • Recyclable Construction: thermoplastic liners and tendons can be reprocessed — unlike thermoset composites.

  • Simplified Production: tendon loops eliminate the need for precision multi-axis winding, allowing modular or field assembly.

Applications

Hydrogen Refueling and Stationary Storage

  • Multi-stage containment allows safe 900–1000 bar storage for refueling stations.

  • Nested tanks provide redundancy, controlled venting, and long-life modular operation.

  • Eliminates the risk of chain-reaction explosions in large hydrogen farms.

Mobile and Aerospace Systems

  • Lightweight tendon systems enable safe high-pressure storage in vehicles, aircraft, and portable power modules.

  • Replace brittle composite tanks with flexible, repairable, impact-resistant structures.

Marine and Shipping — Long CNG Tanks for Fuel and Cargo

  • Global emissions rules are driving a shift from diesel to gas fuels.

  • Current LNG tanks are cryogenic, heavy, and mounted above deck.

  • Flexyshell offers a non-cryogenic CNG solution: long, slender, tendon-tied vessels operating at high pressure.

  • These tanks can be integrated as structural members — hull girders, deck beams, or longitudinal stringers.

  • The result: lighter ships, more efficient layouts, and compliance with emission-control regulations.

  • Suitable for both marine bunker fuel and CNG cargo transport, combining fuel storage and load-bearing functionality.

Summary

Flexyshell introduces a new class of high-pressure hydrogen and gas storage vessel —
tension-based, modular, fail-safe, and repairable.
It overcomes every key limitation of rigid composite tanks: brittleness, delamination, manufacturing cost, and unpredictable failure.
By design, it resists the chain-reaction risk that has long been the weak link in hydrogen infrastructure.
From stationary storage to mobile fuel tanks and marine CNG systems, Flexyshell enables a safer, scalable, and more sustainable high-pressure future.