Jaipur: The fire at the HPCL Rajasthan Refinery Ltd (HRRL) has put the spotlight on the refinery’s Crude Distillation Unit (CDU), the single most critical and expensive component of the project.For a refinery of 9 million tonne per annum capacity, experts estimate the CDU alone costs between Rs 6,000–9,000 crore, consistent with industry benchmarks. With the govt pegging the overall refinery cost at Rs 79,459 crore, the CDU represents the high investment component of the project.HPCL, in its official statement on Tuesday, confirmed that the blaze was triggered by a hydrocarbon leak from a valve flange in the heat exchanger circuit. The fire remained confined to the exchanger stack, with the CDU and adjoining Vacuum Distillation Unit (VDU) immediately isolated. “All units are structurally safe, and no other sections have been impacted,” the company said, seeking to reassure stakeholders.The CDU’s importance cannot be overstated. It is the first stage of refining, where crude oil is separated into fractions such as naphtha, kerosene, and diesel, feeding downstream units that produce fuels and petrochemicals.Industry analysts caution that had the fire spread beyond its containment zone, losses could have exceeded Rs 8,000 crore, with delaying the project. Even localized damage, though less catastrophic, can still mean repair costs running into crores and schedules pushed back by months.Global precedents underline the risks. Mexico’s Dos Bocas Refinery saw operations delayed by several months after a CDU fire, while Kuwait’s Al-Zour Refinery faced similar setbacks. These examples highlight how even a brief blaze can translate into prolonged delays and spiraling costs.HRRL is positioned as the country’s second most complex refinery, with a Nelson Complexity Index of 17, benchmarked against mega-refineries like Reliance’s Jamnagar (68 MMTPA), Vadinar (20 MMTPA), and Paradip (15 MMTPA).Its CDU is central to producing fuels and petrochemicals such as polypropylene, polyethylene, benzene, and butadiene that feed industries from transportation to pharmaceuticals.For now, HPCL’s swift containment has averted a worst-case scenario. The probe currently underway will determine the extent of damage, cost escalation, and the delay in operationalising the state’s most ambitious refinery project.