The West Ethylene Gas Pipeline ruptured in western Kermanshah Province on Sunday, the governor said.
"There are no reports on casualties or damage to property," Fazlollah Ranjbar was quoted as saying by ISNA.
According to the governor, the explosion happened in the eastern region of Mahidasht Valley in Sarfirouzabad region, 10 kilometers from Kermanshah.
"Torrential downpours over the past three weeks followed by landslides caused the blast," he said, noting that there is no known risk to residents in the vicinity of the pipeline as the main valve is closed and the fire has been contained.
The 2,648 km pipeline, known as west ethylene, runs from the port city of Asalouyeh off the Persian Gulf t to West Azarbaijan Province in the northwest, supplying ethylene as feedstock to several petrochemical complexes namely Kouhdasht in Lorestan Province, Sanandaj in Kurdestan Province and Mahabad in West Azarbaijan Province.
According to Qodratollah Farajpour, production manager of the National Petrochemical Company, the massive floods in the region have made it difficult to send equipment to the rugged mountainous region to fix the broken pipeline.
West ethylene is reportedly the longest ethylene pipeline in the world, with a capacity of 2.5 million tons per annum.
The main suppliers of the pipeline are Kavian petrochemical complex in Bushehr Province and Arvand Petrochemical complex in southern Khuzestan Province.
Heavy rainfall that began three weeks ago has destroyed water, power and gas infrastructure in the western and southwestern regions, mainly in Lorestan and Khuzestan.