Process Safety · HAZOP Study
Green Hydrogen Electrolysis Project
HAZOP in Action – From Kick-off to Recommendation Closure
One HAZOP deviation. One missed safeguard. One potentially serious consequence.
This case study presents how a structured HAZOP study was prepared, facilitated and followed through for a 500 TPA green hydrogen production and operation project — covering every stage from kick-off to recommendation closure.
Overview
Project Overview
Aura Safety & Risk Consultants supported a green hydrogen electrolysis project through a structured Hazard and Operability Study (HAZOP), covering the study process from initial kick-off and engineering-document review through node definition, multidisciplinary workshop discussions, recommendation development and action closure.
The production process included six key sections. The HAZOP was used to systematically identify process deviations, understand credible causes and consequences, review safeguards and define practical recommendations where further action was required.
Learn more about Aura Safety's HAZOP Study Services →
Introduction
Why Green Hydrogen Projects Demand Rigorous HAZOP
Green hydrogen projects combine electrochemical processes, gas generation, separation, purification, compression, controls and storage. This makes clear process understanding and multidisciplinary review important when examining how deviations could develop across the plant.
In this project, the HAZOP was treated as more than a worksheet exercise. The focus was on establishing design intent, asking the right technical questions, testing safeguards and ensuring that recommendations could be converted into accountable engineering actions.
Why It Matters
- Hydrogen is flammable across a wide concentration range
- O₂ co-generation creates additional hazard interactions
- High-pressure systems require systematic safeguard review
- Early-stage HAZOP prevents expensive late-design changes
- Multidisciplinary review finds gaps no single engineer sees
Study Objectives
Objectives of the HAZOP Study
Deviation Identification
Identify process deviations across the entire green hydrogen production system.
Cause Analysis
Understand credible causes associated with each identified deviation.
Consequence Challenge
Challenge potential consequences and escalation scenarios systematically.
Safeguard Review
Review the adequacy of existing safeguards and controls at every node.
Recommendations
Develop clear, practical and traceable recommendations for engineering action.
Safer Design
Support safer design decisions and more reliable future plant operation.
Preparation Phase
Before the HAZOP Workshop
The case study shows that effective HAZOP preparation begins well before guide words are applied. Study quality depends heavily on how clearly the scope, technical information, process boundaries and nodes have been prepared.
- Kick-off: align the team on purpose, scope, team composition, ground rules and schedule.
- Document Review: review relevant engineering documents for accuracy, completeness and current revision status.
- Process Understanding: understand process intent, equipment function, utilities and operating methods.
- Node Marking: divide the process into logical sections that enable focused, structured discussion.
- Node Finalisation: confirm and approve the node list with the full HAZOP team before commencing the workshop.
Document Review
Engineering Documents Reviewed
The project review used the available engineering information to establish what the plant was intended to do before assessing how it could deviate from that intent.
PFDs / P&IDs
Process flow, connections and equipment layout for the full plant.
Process Design Basis
Design assumptions, criteria and operating parameters.
Equipment Datasheets
Ratings, design limits, materials of construction.
Cause & Effect Diagrams
Possible causes, expected process responses and alarm settings.
Control Philosophy
Control strategies, interlock logic and key safeguards.
Line / Equipment Lists
Supporting process information for all streams and equipment items.
Relief Philosophy
Overpressure-protection strategy, relief valve set points.
Utility Information
Utility requirements, design limits and supply interdependencies.
Every document helps the team understand the intended design — and therefore what a deviation actually means.
Node Definition
HAZOP Node Marking
Node selection was approached as more than a drawing exercise. The team considered six key factors when defining each node to ensure meaningful, focused workshop discussions.
Process Intent
Define what each section of the process is intended to achieve operationally.
Equipment Function
Understand the role of each equipment item within its process section.
Control Boundaries
Recognise where control strategies and operating conditions change across the plant.
Interfaces
Pay particular attention to transitions and handoff points between process sections.
Operating Conditions
Consider all relevant parameters: pressure, temperature, flow and composition.
Clear Design Intent
Keep one clear, unambiguous design intent per node wherever practical.
Clear node marking + clear design intent = a more effective HAZOP discussion.
Workshop Phase
The HAZOP Workshop: Guide Words Applied
Once preparation was complete, the multidisciplinary team used guide words to challenge how the process could differ from its intended operation. Examples illustrated in the case study:
The team did not stop at "What can fail?" The discussion examined what could happen when the process did not behave as intended.
Example Scenario
A Realistic Hydrogen HAZOP Discussion
One of the scenarios presented in the case study involved hydrogen and oxygen cross-contamination inside the electrolyser separator. The discussion followed the potential development of the scenario step by step.
The team challenged the scenario by asking:
- How would the condition be detected?
- What happens if the analyser fails?
- Does the shutdown happen automatically?
- What happens to the gas during the abnormal condition?
Good questions uncover weak points. Better understanding supports safer design decisions.
Workshop Discipline
Key HAZOP Discussion Points
For each credible deviation identified, the workshop focused on eight structured questions:
- Is the cause credible?
- What is the immediate consequence?
- What is the worst credible consequence?
- How is the deviation detected?
- Is the safeguard available in time?
- Is the safeguard independent?
- What happens if the safeguard fails?
- Does the recommendation improve the design?
HAZOP is not a spreadsheet exercise. It is a structured conversation about uncertainty.
From Finding to Action
From Finding to Recommendation
The case study shows that a recommendation should solve an identified problem rather than simply fill a worksheet row. Each potential finding was discussed technically before an action was finalised.
- Finding: identify a potential HAZOP issue from the guide word + deviation discussion.
- Discussion: evaluate causes, detection, protection and safeguard independence.
- Challenge: assess whether existing safeguards are adequate for the worst credible consequence.
- Action: define clearly how protection should be improved or verified.
Following multidisciplinary discussion, a recommendation could be refined, merged, rewritten or rejected. The objective was to arrive at technically meaningful actions with a clear engineering basis.
Recommendation Quality
Recommendation Finalisation
A strong recommendation needs enough detail to be assigned, implemented and verified. The case study highlights six practical questions every recommendation must answer:
Post-Workshop Phase
After the Workshop
The HAZOP did not end when the workshop ended. The follow-up process presented in the project moved through a formal five-stage closure path:
This follow-up is essential because a recommendation that is never implemented is not a completed risk reduction. Strong action tracking turns workshop discussions into practical, verifiable risk-reduction measures.
Outcome & Value
Outcome & Project Value
The case study presents the value of the HAZOP primarily in qualitative engineering and project terms. Four outcomes were consistently achieved across the study:
Better Design
Potential problems were challenged while design changes were still possible — avoiding expensive rework during construction or commissioning.
Shared Understanding
Process, instrumentation, mechanical, electrical, operations and HSE disciplines reviewed the same scenarios together, closing knowledge gaps across teams.
Traceable Actions
Recommendations became owned and trackable engineering actions — with a named responsible party and closure evidence required for each one.
Preventive Thinking
Potential failure chains — including the H₂/O₂ cross-contamination scenario — were examined and addressed before they could become operational incidents.
Sector Context
Why HAZOP Is Important for Green Hydrogen Projects
In a green hydrogen facility, interactions between hydrogen, oxygen, electrical energy, pressure, controls and process equipment require systematic examination. A structured HAZOP helps the project team identify deviations, test assumptions, examine safeguards and document actions before issues become operational problems.
The central lesson from this project is simple: challenge the design before the design challenges you.
For broader context, read Aura Safety's Green Hydrogen Safety: Understanding Hazards and Managing Risks →
Our Services
Partner with Aura Safety & Risk Consultants
Aura Safety supports process industries with structured hazard identification and risk-assessment studies designed to improve process understanding, challenge safeguards and convert findings into practical engineering actions.
FAQs
Frequently Asked Questions
What was the scope of this green hydrogen HAZOP case study?
The case study covers a 500 TPA green hydrogen production and operation project and follows the HAZOP process from kick-off and preparation through workshop discussions, recommendations and formal closure of every action.
Which process sections were part of the project?
The source material identifies water treatment, a PEM electrolyser, gas/liquid separation, hydrogen purification, compression and storage/export within the green hydrogen production process — six distinct process sections.
Why was node marking important?
Node marking helped create logical study sections with clear design intent. The project considered equipment function, control boundaries, operating conditions, interfaces and changes in pressure or temperature — ensuring each workshop session had a focused and productive scope.
What hydrogen-related scenario was examined?
The case study illustrates an H₂/O₂ cross-contamination scenario and challenges how the condition could develop — from abnormal differential pressure through membrane deterioration and gas crossover to unsafe composition and ignition potential — and what safeguards would respond at each stage.
Does HAZOP follow-up continue after the workshop?
Yes. The case study shows a formal five-stage follow-up path: Report → Action Owner → Technical Response → Evidence → Closure. A recommendation that is never implemented is not a completed risk reduction.
Can Aura Safety conduct a HAZOP for our green hydrogen or hydrogen project?
Yes. Aura Safety & Risk Consultants delivers HAZOP studies for green hydrogen, renewable energy, chemical, oil & gas, and manufacturing projects across India. Contact us to discuss your project stage, scope and timeline.
