Hungary - MOL Completes Reconstruction of the AV3 Unit at Danube Refinery
Hungary – MOL Completes Reconstruction of the AV3 Unit at Danube Refinery
MOL Completes Major Reconstruction at Danube Refinery
Hungarian energy company MOL Group has completed the reconstruction of the AV3 crude oil distillation unit at its Danube Refinery in Százhalombatta, marking an important milestone in the recovery of one of Hungary’s key refining facilities.
The AV3 unit was significantly damaged by a fire in October 2025. After almost a year of reconstruction work, MOL has now completed the construction phase according to the preliminary schedule.
The refinery will next move into commissioning, testing and preparation for a gradual restart. MOL expects production from the reconstructed unit to resume step by step in October 2026.
HUF 18 Billion Reconstruction Project
The reconstruction required a major engineering and construction effort.
MOL reported that the total repair budget was approximately HUF 18 billion, equivalent to around €50 million. The project involved rebuilding damaged structures and replacing or restoring critical refinery equipment and systems.
Among the major works completed were:
Demolition and reconstruction of the damaged reinforced-concrete structure
Restoration of affected process equipment
Restoration of control and electrical systems
Installation of 27 new high-capacity pumps
Replacement of approximately 8 kilometres of piping
Installation of around 100 kilometres of electrical cables
The scale of the reconstruction highlights the complexity of restoring a major crude oil processing unit following significant fire damage.
Fire Damaged the AV3 Crude Distillation Unit in 2025
The AV3 unit was damaged during a fire at the Danube Refinery in October 2025.
MOL's initial investigation determined that the incident was caused by equipment failure and the subsequent rupture of a pump. The company said that gross negligence, wilful misconduct and external impact could be ruled out as possible root causes based on its internal investigation.
The incident temporarily reduced the refinery's available processing capacity and required MOL to introduce measures to maintain fuel supplies while reconstruction work was carried out.
MOL Maintained Fuel Supply During the Repair Period
During the refurbishment, MOL implemented several measures to compensate for the reduced processing capacity at the Danube Refinery.
The company increased the processing of semi-finished feedstock and transferred additional products from its Bratislava Refinery. MOL also increased third-party imports from the region to help maintain fuel availability across its markets.
MOL had previously estimated that production losses would average approximately 30% over the refurbishment period, although the impact varied depending on the stage of the reconstruction.
These measures allowed the company to continue supplying customers while the damaged AV3 unit was being rebuilt.
What Happens Before the AV3 Unit Restarts?
Although construction is now complete, the refinery will not immediately return to full operation.
Restarting a complex crude distillation unit requires extensive testing and safety checks before crude oil can be introduced.
According to MOL, the next stages include:
Flushing refinery systems
Conducting pressure tests
Testing process-control equipment
Testing safety systems
Connecting auxiliary power supplies
Coordinating AV3 operations with other refinery units
Carrying out operational safety inspections
Gradually introducing crude oil into the unit
MOL expects production to restart gradually in October.
Why the AV3 Unit Matters
The AV3 unit is an important part of the Danube Refinery's crude oil processing system.
The Danube Refinery in Százhalombatta is a major refining facility serving Hungary and the wider Central European region. Returning the AV3 unit to service will increase the refinery's available processing capacity and provide MOL with greater flexibility in meeting domestic and regional fuel demand.
The company has described the return of the unit as an important step in strengthening fuel-supply security for Hungary and the surrounding region.
Strengthening Hungary's Refining Capacity
The completion of the reconstruction comes at a time when European energy markets remain focused on refining capacity, crude supply diversification and fuel-security risks.
The loss of a major refinery unit can affect regional fuel balances, particularly when replacement supplies have to be sourced through imports or transfers from other refineries.
With AV3 returning to service, MOL will have another important processing asset available within its refining network.
The company expects the restored capacity to provide greater flexibility in responding to changes in regional demand and supply conditions.
Safety Remains a Key Priority
MOL has emphasized that the restart will take place gradually rather than immediately returning the unit to full production.
This approach reflects the complexity of restarting a large industrial processing facility after extensive reconstruction.
Before normal operations resume, the company will conduct multiple technical, functional and safety tests. The equipment and associated refinery systems must operate reliably together before the unit can return to regular crude processing.
The priority during this stage is therefore not simply speed of restart but ensuring that the reconstructed facility can operate safely and reliably.
Regional Impact on the Fuel Market
The return of AV3 could have implications beyond MOL's own operations.
The Danube Refinery supplies fuel to Hungary and other markets in Central Europe. Restored refining capacity can reduce the need to compensate for lost production through additional imports or transfers from other facilities.
This could provide MOL with greater flexibility in managing regional fuel flows, although the actual market impact will depend on refinery utilization, crude availability, regional demand and broader European fuel-market conditions.
A Major Step in MOL's Refining Strategy
The completion of the AV3 reconstruction demonstrates MOL's continued investment in maintaining its existing refining infrastructure.
Rather than permanently replacing the lost capacity with imports, MOL has undertaken a comprehensive reconstruction of the damaged unit.
The project involved significant replacement of mechanical, electrical and control infrastructure, including new pumps, piping and electrical cables.
Once the commissioning process is completed, the Danube Refinery will regain an important part of its processing capability.
What to Watch Next
The key developments to monitor in the coming weeks include:
The start of AV3 commissioning
Completion of pressure and functional testing
Gradual introduction of crude oil
The timing of the return to normal production
Refinery utilization rates following the restart
Changes in regional fuel imports
The impact on Central European fuel supply and refining balances
Successful completion of these stages will determine when the Danube Refinery can fully benefit from the restored unit.
Conclusion
MOL's completion of the AV3 reconstruction at the Danube Refinery marks a major milestone following the fire that damaged the crude oil distillation unit in October 2025.
The approximately HUF 18 billion reconstruction project involved rebuilding damaged structures, installing 27 high-capacity pumps, replacing 8 kilometres of piping and laying approximately 100 kilometres of electrical cables.
With construction now complete, MOL is moving into the commissioning and testing phase. Production is expected to resume gradually in October 2026 following extensive safety and operational checks.
The return of AV3 will restore an important part of the Danube Refinery's processing capability and is expected to strengthen MOL's flexibility in supplying fuel to Hungary and the wider Central European market.
The next major milestone will be the successful restart of the unit and its return to stable commercial operation.
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