(3) Establishment of factories for other varieties of steel pipes

During this period, larger pipe rolling workshops were also built and put into operation, and began to produce special pipes required by petroleum, aerospace, ships, boilers and other industries. In order to meet the needs of the construction of oil and natural gas pipelines, China has successively built and put into operation large-diameter spiral welded pipe units in Jinzhou Steel Pipe Factory, Ziyang Steel Pipe Factory and Shengli Oilfield Steel Pipe Factory.