BEIJING—The death toll from a pair of oil pipeline explosions on Friday in the eastern China port city of Qingdao has risen to 52, with another 11 people still missing, the city government reported Sunday.

pipeline:管道，输油管           

Citing rescuers, the Qingdao government information office said in a statement posted on its official microblog feed that the death toll rose after rescue teams found additional bodies in the rubble.

rubble：碎石，碎砖    

The blasts, which occurred on Friday morning, left a total of 136 injured, with 10 in critical condition, the official Xinhua news agency said, in a report that cited provincial health authorities.

blast：爆炸      

Separately on Sunday, state-owned Sinopec Group, which owns the pipeline, said in a post on its official microblog feed that tests of pipes in the area had eliminated concern over the possibility of a secondary gas explosion.

Sinopec Group：中国石化集团            

The pipeline explosion was one of the most destructive industrial accidents in China so far this year.

Petroleum from the pipeline has contaminated some 3,000 square meters of water and 18,000 people have had to be evacuated, according to authorities.

petroleum：石油           evacuate：疏散，撤退

Photographs posted online, which couldn't be verified, showed roads reduced to rubble, vehicles flipped one their sides and windows shattered in nearby residential buildings.

shatter：碎片，打碎，粉碎           

Sinopec quoted its chairman, , apologizing to the city in a statement posted online on Saturday, and said it was continuing to cooperate with authorities in investigating the causes of the blast.

Chinese President Xi Jinping and Premier  both publicly addressed Friday's accident, calling for more efforts to search for survivors, an investigation into the cause of the blasts and better safety measures, according to state media.

The first explosion occurred in the Huangdao district of the city of Qingdao as workers were trying to fix the pipeline, which had begun leaking early Friday morning, causing oil to spill into the city's drainage pipe system.

spill into：涌进                 drainage pipe：排污管，排水道

According to local authorities, a separate explosion occurred at roughly the same time after petroleum leaked into a nearby estuary. Six of those killed were firefighters affiliated with a Sinopec oil depot in Huangdao, according to Xinhua.

estuary：河口，江口            affiliate with：交往           oil depot：油库

Sinopec, which is China's largest oil refiner, has previously faced protests and other complaints from residents in other cities over its efforts to build oil refineries and other petrochemical plants near densely populated area.

petrochemical plants：石油化工装置

The damaged pipeline, which connects oil depots in Huangdao with processing facilities in the city of Weifang roughly 170 kilometers away, had been in use since 1986, according to Xinhua. The pipeline, which can ship about 200,000 barrels a day, was built in 1986 and stretches about 250 kilometers in total.

barrel：机筒，滚筒         

The pipeline hasn't been immune to problems.

immune to：不受...感染，免疫   

In 2010, for example, company statements describe two accidents along the pipeline due to the buildup of trash on a section of the pipeline and illegal construction near it, according to company statements. Although the accidents involved oil spills and fires, no casualties were reported, according to company statements. Sinopec said at the time that it spent 12 million yuan (about $2 million) between 2005 and 2010 to fix sections of the pipeline that had severe corrosion.

casualty：伤亡，人员伤亡        corrosion：腐蚀，衰败  

The company operated 7,100 kilometers of crude pipelines at the end of last year, company statements show.