The 2025 general overhaul of Tehran Oil Refinery began on October 27 and continued for 18 days. Focused on the atmospheric distillation unit, vacuum distillation unit, southern LPG unit, and Merox unit, the maintenance work went beyond normal repairs and was designed to improve equipment performance, enhance process stability, and reduce operational risks. The main approach during this overhaul was reconstruction and optimization of systems using domestic capabilities—over 90 percent of the required equipment and materials were sourced locally.

This overhaul also saw the use of new methods such as robotic tank thickness measurement. The introduction of this robot reduced the thickness-measurement time for storage tanks from one month to less than two days. Tehran Refinery is currently the only refinery in the country using this technology.

The refinery’s overhaul operations were completed through precise coordination and intensive work shifts, marking a major achievement for enhancing safety and sustaining production at Tehran Oil Refinery.

Mohammad-Qorban Feyzabadi, head of maintenance planning at Tehran Refinery, emphasized in an interview with Shana the vital importance of timely and accurate maintenance in the nation’s refinery complexes. He noted that the overhaul began on October 27 and lasted 18 days, targeting improvements in quality, performance, and operational risk reduction across the southern distillation complex, including atmospheric and vacuum distillation units, the southern LPG unit, and the Merox unit. He added that the overhaul was not limited to fixing faults; the aim was to improve equipment performance, increase product quality, ensure operational stability, and simultaneously carry out reconstruction and repairs.

He explained that general overhauls of the southern distillation complex occur every four years and stressed the importance of timely maintenance—not only for preserving equipment but also for improving safety and production quality.

Feyzabadi highlighted that more than 90 percent of the equipment and materials needed for this overhaul were sourced domestically. He noted the use of advanced technologies—such as scanning tools, specialized cameras, and robotic tank-thickness measurement systems—to detect corrosion and equipment issues.

He also pointed to efforts to reduce emissions, noting that alongside technical repairs, the sulfur recovery unit was also overhauled. This not only improved operational performance but also helped reduce environmental pollution.

Regarding challenges, Feyzabadi stated that the main difficulty was the limited timeframe. Because the overhaul was conducted under tight deadlines, some operations had to be performed simultaneously around the clock, requiring precise coordination and optimal use of manpower and equipment.

Reconstruction of 40% of Mechanical Equipment at Tehran Refinery

Reza Zarei, head of mechanical maintenance at Tehran Oil Refinery, explained the broad responsibilities of the mechanical department and the challenges of the overhaul. The mechanical division includes machinery units, the central workshop, and maintenance sections—overseeing all mechanical equipment, including piping, lines, pumps, compressors, gas and steam turbines.

He noted that the mechanical division leads the refinery’s general overhaul, since the majority of equipment requiring testing, repair, and rebuilding are mechanical. The refinery’s central workshop is a particular strength, completing most repair work in-house, with only specialized tasks such as plating or casting outsourced. He added that in this overhaul, five to six heat exchangers were completely retubed through round-the-clock work.

Zarei emphasized that most mechanical equipment used in the refinery is now domestically manufactured. Sanctions, he noted, created opportunities for greater innovation; although a large portion of the refinery’s equipment originates from the U.S. or Europe, reconstruction is now being carried out using local expertise.

He explained that all mechanical equipment is opened, inspected, and cleaned during an overhaul, and about 30–40 percent is rebuilt. Completing this large volume of work within a short timeframe required nonstop efforts. To meet the 18-day schedule, work was split across two day–night shifts.

Critical Role of Inspection in Safety, Production Continuity

Abdolvahab Deliri, head of technical inspection at Tehran Refinery, highlighted the essential role of inspection in ensuring safety and continuous production. He explained that general overhauls occur every four years. During these overhauls, all operational equipment—including furnaces, piping, heat exchangers, and air coolers—undergo thickness testing. If reduced thickness is detected, the inspection unit issues repair orders, which are then carried out by maintenance teams.

He stressed adherence to technical standards, noting that at the end of repairs and before equipment handover, nondestructive tests—PT, MT, and RT—are conducted to ensure full compliance with safety and quality standards. During this overhaul, approximately 40,000 measurement points were tested, with results compared against baseline thickness records.

Deliri described the new technologies used to accelerate inspections. The robotic tank-thickness measurement system, introduced during this overhaul, reduced the duration of tank inspection from one month to less than two days—making Tehran Refinery the only refinery in the country currently using this tool.

He outlined the structure of the inspection department, which includes 28 specialists across four divisions: process inspection (for units and operational equipment), general inspection (for tanks and off-unit facilities), nondestructive testing, and corrosion analysis and prevention.

Deliri concluded by saying their goal is to ensure inspected equipment operates without issues for the next four years. If problems arise during this period, they are analyzed as case studies and corrective actions are applied in the next overhaul cycle. He noted that the inspection staff possess a high level of expertise, having completed specialized training either inside the refinery or through external inspection firms.