Safety at speed: delivering ATEX compliance during ramp-up

Brownfield hydrogen conversions rarely have the luxury of a clean-sheet schedule. The pressure to bring assets online quickly can collide with ATEX obligations, especially when existing equipment was never designed for hydrogen. The goal is not to shortcut safety; it is to sequence it. A phased compliance strategy keeps the project moving while steadily building a defensible ATEX dossier.

Hydrogen changes the hazard profile

Hydrogen has a low ignition energy, wide flammability range, and high diffusivity. That combination turns small leaks into meaningful risk. In practical terms, it means your hazardous area classification will often expand relative to natural gas, and your detection thresholds need to be tighter. The focus shifts from large releases to persistent low-level leaks that can accumulate in enclosed or partially enclosed spaces.

Start with a structured gap assessment

A gap assessment should happen before procurement ramps up. Build a register that combines P&IDs, hazardous area classification drawings, electrical equipment schedules, and existing Ex certificates. Map each item to ATEX categories and identify mismatches early. This is where you will discover that cable glands, HVAC components, and instrumentation cabinets are often the weakest links.

Design a phased compliance plan

Phasing does not mean deferring safety. It means defining which systems must be fully ATEX-compliant before first gas and which can be temporarily mitigated under strict controls. For example, you can commission inert or nitrogen systems before the hazardous area classification is final, then lock down access and restrict energisation until Ex-rated components are installed. Formalise each phase through a management of change process so the record is audit-ready.

Engineering controls that buy time safely

Focus on the controls that reduce ignition probability and limit the accumulation of hydrogen. Typical priorities include high-sensitivity gas detection, forced ventilation with alarmed airflow, automatic ESD logic tied to detection thresholds, and pressure relief routing away from occupied areas. Earthing and bonding should be verified early because they are low-cost but high-impact risk reducers. Where equipment cannot be replaced immediately, evaluate temporary enclosures or barriers and document their limits.

Operational controls and culture

ATEX compliance is not just hardware. It is how the site operates during a dynamic ramp-up. Permit-to-work practices must be updated to reflect hydrogen zones and ignition sources. Contractors need a clear briefing on what changed and why. Simultaneous operations (SIMOPS) should be tightly managed, with defined exclusion zones during leak testing or venting. A short, repeatable start-up checklist reduces the chance of drift.

Documentation that regulators expect

Regulators and insurers look for a coherent chain of evidence. That includes a complete ATEX dossier, hazardous area classification documentation, equipment certificates, and functional safety analyses. Where your project straddles DSEAR and PED requirements, the interfaces must be explicit. It is worth maintaining a single compliance register that ties each asset to its certification status and inspection date.

Commissioning and ramp-up hold points

Hydrogen commissioning should include clear hold points for leak testing, detector validation, and ESD loop checks. The transition from inerting to live hydrogen is the highest-risk period, so it deserves a dedicated procedure with clear sign-off. Keep the first hydrogen introduction short and controlled, capture data, and review it before moving to continuous operation.

Leading indicators that show control

Use leading indicators to prove your control regime works. Examples include the percentage of Ex-certified equipment installed, detection system uptime, number of permit deviations, and completion of safety-critical training. These metrics give leadership confidence and allow you to defend a phased approach with evidence, not assumptions.

Key takeaways

• Hydrogen expands hazardous area boundaries and increases the importance of leak detection.
• Phased ATEX compliance must be documented through formal management of change.
• Engineering and operational controls are equally important during ramp-up.
• Hold points and leading indicators keep the project defensible under scrutiny.