New Delhi | Hindustan Petroleum Corporation Limited (HPCL) on Tuesday said a fire at its Rajasthan refinery is not expected to have a material financial or operational impact, adding that all units are structurally safe.

The fire broke out on April 20 in the crude distillation unit and was likely caused by a hydrocarbon leak from a valve or flange in a heat exchanger circuit, the firm said in a stock exchange filing.

The blaze was confined to the heat exchanger stack and was quickly brought under control by the site's emergency response team.

There were no casualties or injuries.

The crude distillation unit, vacuum distillation unit and associated sections were isolated as a precaution, the company said.

A scheduled April 21 dedication of the refinery by Prime Minister Narendra Modi has been postponed. A revised date will be announced.

An investigation has been initiated to determine the cause and implement remedial measures.

"An unfortunate accident occurred (on Monday) at around 1.55 pm at HPCL Rajasthan Refinery Ltd (HRRL) at Pachpadra, Balotra. There was a fire in the Crude Distillation Unit (CDU) section of the refinery complex. Prima facie, it appears that leakage of hydrocarbons through one of the valves/flanges in the heat exchanger circuit caused the fire," HPCL said.

The fire was promptly brought under control by the emergency response team of HRRL with support from the local administration.

There is no loss of life or injury to any personnel, it said, adding the fire was localised in the heat exchangers stack.

Crude Distillation Unit (CDU), Vacuum Distillation Unit (VDU), and all other units of the CDU section were quickly isolated. All are structurally safe and unaffected. "No other section of the refinery has suffered any impact." The cause of this fire and its impact on the Unit are being assessed and investigated by a team of internal and external experts, it said.

"An investigation has been initiated to ascertain the cause of the incident and to undertake necessary remedial measures," HPCL said. "The financial and operational impact, if any, is being assessed and prima facie is not expected to be material." All are structurally safe and unaffected, it said. "No other section of the refinery has suffered any impact." A major fire broke out near the main unit of the newly built Rs 79,450-crore Rajasthan refinery on Monday, a day before the scheduled inauguration by Modi.

Refineries worldwide are highly susceptible to fires, explosions, and catastrophic failures during the commissioning and startup phases, as this period involves introducing hydrocarbons into new or maintained high-pressure, high-temperature systems.

For this reason, inauguration ceremonies are performed after all units (a refinery typically has several units that turn crude oil pumped out of the ground or below the seabed into fuels like petrol and diesel at high temperatures) are safely commissioned and operations stabalised.

The refinery project was scheduled to begin commercial operations from July 1, according to a Government of India statement issued on April 8, announcing approval of the Union Cabinet to enhance the cost of the project.

This is not the first time a fire has broken out at a refinery under commissioning. On January 30, 2016, a major fire broke out at Indian Oil Corporation's (IOC) Paradip refinery's atmospheric vacuum unit (AVU), just over a week before its scheduled inauguration by Prime Minister Modi on February 7, 2016. No injuries were reported even then.

The Rajasthan refinery will be India's 24th and the second most complex unit yet in India.

The refinery-cum-petrochemical complex, located in Rajasthan's Balotra district, is designed as a 9 million tonnes per annum facility with a strong petrochemical focus, reflecting India's strategy to boost value-added output and reduce import dependence.

It features a Nelson Complexity Index of 17 and petrochemical yields exceeding 26 per cent, aligning with global benchmarks for efficiency and sustainability, according to an official statement.

Refinery complexity -- often measured by the Nelson Complexity Index -- indicates the capability to handle heavier, dirtier crude oil (which is cheaper) and turn it into high-value products like gasoline and diesel.

Reliance Industries Ltd's Jamnagar refinery in Gujarat is the world's most complex and largest refinery, featuring a complexity index of 21.1 and the capability to process over 216 different crude oil grades. It is designed to convert low-value heavy/sour crude into high-value fuels, processing 1.24-1.4 million barrels per day (Rajasthan refinery has a processing capacity of 180,000 barrels per day).

HRRL is a joint venture between HPCL, which holds a 74 per cent stake, and the Government of Rajasthan with the remaining 26 per cent.

Once operational, the complex will produce fuels, including petrol and diesel, along with petrochemicals such as polypropylene, polyethylene variants and key industrial chemicals like benzene and butadiene.

These products are widely used across sectors ranging from transportation and packaging to pharmaceuticals and construction.