The blast injured another 156 and caused a loss of 751.72 million yuan (about USD 123 million),the people's court of Huangdao District of Qingdao City said in its verdict.
The main reason for the accident was maintenance staff drilling, which produced sparks and caused an explosion fueled by oil leaked from a pipeline owned by a subsidiary of Sinopec, the country's largest oil refiner, a report unveiled last year by a special investigation group set up by the State Council said.
Another six people from the local government were sentenced three years to three and a half years for dereliction of duty, state-run Xinhua news agency reported.
Four people were given a two-year reprieve.
Over 60 people have been penalised for the blast, with at least 48 receiving punishments for violating Party and administrative disciplines.