With the help of this mill train high-quality big-caliber straight-seam welded pipes conforming to API, SPEC and 5L (42 version) can be produced. The main pipes produced include: petroleum and natural gas pipes; water coal slurry and ore slurry pipes; civil construction coal, water supply and drain and heating supply engineering pipes; structural pipes with big wall thickness; piling pipe for bridge; chemical pipeline; electric power station pipeline and pipelines with other applications, etc.