This is the second time the refinery, based in the central province of Quang Ngai, has been closed down for such a process, three years after the first in 2011.

BSR has selected three international contractors, including Singapore’s Heap Seng and Korea’s Dea Chang and Ubec for the project, according to the company website.

Two experienced Vietnamese firms, PTSC Quang Ngai Petroleum Services Enterprise and PetroVietnam Maintenance and Repair JSC will also take part in the maintenance.

Maintenance work is expected to last 57 days, five days shorter than the first process, according to the BSR.

“The maintenance process will be conducted 24/7 by 3,000 professionals from BSR and its international contractors and partners,” company spokesman Pham Minh Nghia said.

Around 1,000 engineers from BSR will contribute to the project, he added.

The first-ever oil refinery of Vietnam, Dung Quat opened in 2009 with a capacity of 6.5 million tons of crude oil annually, or 140 thousand barrels per day.

Vietnam has also announced its second planned oil refinery, the US$9 billion Nghi Son plant, which will be located in the Nghi Son Economic Zone in Thanh Hoa Province.

The facility is expected to begin commercial production in 2017, the state-run Vietnam Oil and Gas Group (PetroVietnam) announced in a statement early last year.