Qatar Liquefied Gas Co., known as Qatargas, plans to halt operations at three of its liquefied natural gas production units to carry out maintenance work, an official at the company said. The work on train 6 will start in mid-September and work on train 5 will take place at the start of October after which work on train 7 is scheduled to begin, said the official, who asked to remain unidentified in line with company policy. Maintenance work on each train will take two weeks, the official added.