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Hyperbaric TunnellingHyperbaric Interventions

Mixed-gas hyperbaric interventions above 3.0 bar for deep TBM operations

What is High-Pressure Compressed Air — Heliox / Trimix?

High-pressure hyperbaric interventions above 3.0 bar using heliox or trimix breathing mixtures to eliminate nitrogen narcosis and reduce decompression risk in deep TBM operations.

What's Included

  • Mixed gas supply system setup and verification (heliox/trimix cylinders, manifolds, bailout sets)
  • HPCA personnel lock operations with mixed gas decompression
  • Cutterhead tool inspection and replacement at pressures 3.0–3.6 bar
  • Structural repairs and obstruction removal in the excavation chamber
  • Emergency face closure and pressure bleed-down procedures
  • Post-intervention decompression with oxygen decompression stops
  • Breathing gas analysis and quality verification before each intervention

Why This Matters

Mixed-gas HPCA operations allow KCC to safely access TBM cutterheads in deep urban tunnels where groundwater pressures exceed the safe limit for compressed air. This capability is increasingly critical as tunnel drives extend deeper beneath Hong Kong's harbour and urban areas.

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IMCA ADCI HSE HKCP

IMCA · ADCI · HSE · HKCP Compliant

All diving operations conducted to IMCA, ADCI, HSE & HKCP standards

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