Introduction
This HAZOP and LOPA case study fuel depot BPCS upgrade examines how a legacy fuel depot improved its control and safety systems to better protect against tank overfill and loss of containment.
OTECSA Consulting Ltd facilitated a four day HAZOP and LOPA workshop with a multidisciplinary client team to identify credible hazardous scenarios, review existing safeguards, and assess whether the proposed protection layers were sufficient to reduce risk to an acceptable level.
The project focused on practical risk reduction, environmental protection, and proportionate safety design.
Project background
The site is a long established fuel terminal with operations that were originally designed to be largely manual. Because of the age of the facility, the project team worked with a mixture of P and IDs, historic drawings, and existing plant information that was not always easy to access.
A site walk around was an important part of the preparation and study process. It helped the team verify the layout, understand the physical arrangement of equipment, and confirm how the site operated in practice.
The new control philosophy did not aim to fully automate the site. Instead, it introduced additional automated safeguards to support the existing manual operation.
HAZOP study scope
The HAZOP study focused on the parts of the facility included within the BPCS project scope. This included:
- Storage tanks and overfill protection systems
- Fuel transfer operations
- Oil and water separators and site drainage systems, including oil in water detection
- New instrumentation linked to alarms and ROSOVs
The study used the standard HAZOP approach, splitting the process into nodes and applying guidewords to assess deviations from normal operation. Where groups of tanks operated on a similar basis, common scenarios were grouped efficiently so the team could focus on the most representative and potentially worst case situations.
Main hazards identified
The key hazard identified during the study was release of fuel into the environment. Due to the higher flashpoint nature of the fuels stored on site, fire and explosion risks were assessed as low.
The principal concern was uncontrolled fuel discharge leading to pollution and significant environmental impact.
Scenarios considered included:
- Overfill of storage tanks due to operator or instrument failures
- Unintended transfer of fuel into drainage or separator systems
- Manual dewatering activities not being completed correctly
- Abnormal flow conditions that could overwhelm the separators
The study also considered lower frequency operations such as tank to tank transfer, where human error or missed isolation steps could lead to an unintended release.
LOPA assessment
Three multi cause LOPAs were completed for selected scenarios identified through the HAZOP. These included:
- Tank overfill protection scenarios
- Separator related scenarios involving abnormal fuel ingress
- Manual operation scenarios linked to dewatering and transfer activities
For the dewatering related scenarios, the analysis showed that the existing controls and infrequent nature of the operation already reduced the risk to a tolerable level.
For the tank overfill scenarios, the LOPA identified a risk gap. The conclusion was that an independent shutdown function was required, but the gap did not justify a high integrity SIL rated trip. An independent trip, separate from the BPCS, was considered sufficient when combined with the existing procedural controls and independent checks already in place.
This gave the client a proportionate solution. Additional protection was needed, but not an unnecessarily complex one.
Outcomes
The HAZOP and LOPA workshops delivered a concise review of the site’s main hazards and supported the design of a proportionate protection strategy.
The study:
- Identified credible fuel release scenarios
- Confirmed that the principal hazard on site was environmental pollution
- Reviewed the proposed safeguards and recommended further protection where required
- Calculated the required integrity level of critical instrumented trips in the LOPA
- Identified where independent protection was needed
- Demonstrated that several scenarios were already tolerable with existing controls
The result was a practical set of recommendations that supported safer operation without unnecessarily increasing system complexity.
Lessons Learned from this HAZOP and LOPA Case Study
- A key lesson from the study was the value of early preparation, especially on a site with older drawings and a long operational history. Where documentation is incomplete or difficult to interpret, a site tour can make a major difference to how effectively the HAZOP progresses.
- Another clear takeaway was the importance of an engaged HAZOP team. The study was efficient and constructive because the client representatives were active, knowledgeable, and willing to contribute. That collaboration made it easier to identify credible scenarios and agree on suitable safeguards.
Why HAZOP and LOPA matter for fuel depot upgrades
A HAZOP and LOPA case study like this shows how structured process safety methods can support safe design decisions on existing sites.
For fuel depots and other sites with ageing infrastructure, these studies help teams:
- Understand credible hazards
- Check whether safeguards are adequate
- Identify risk gaps early in the project
- Avoid over engineering while still maintaining safety
- Support ALARP decision making with evidence
Conclusion
This HAZOP and LOPA case study fuel depot BPCS upgrade supported the safe modernisation of a legacy fuel depot by identifying environmental hazards, reviewing the adequacy of existing safeguards, and confirming where additional protection was required.
The proportional and robust approach taken in the HAZOP and LOPA study provided confidence in the proposed BPCS design and demonstrated that risks on site could be managed and reduced to ALARP levels.
If you need support with HAZOP, LOPA, or BPCS upgrade projects, get in touch with our team to discuss how we can help.