Q345E steel pipes feature hollow sections, with lengths exceeding their diameters and circumferences. They are categorized by cross-sectional shape into round, rectangular, and special-shaped steel pipes; by material into carbon structural, low-alloy structural, alloy, and composite steel pipes; by application into transport pipelines, engineering structures, thermal equipment, petrochemical industry, machinery manufacturing, high-pressure equipment, etc.; and by production process into seamless and welded steel pipes, with seamless pipes further divided into hot-rolled and cold-rolled (drawn) types, and welded pipes into straight seam and spiral seam types.

Q345E steel pipes are not only used for transporting fluids and powdered solids, exchanging thermal energy, manufacturing mechanical parts and vessels, but they also represent an economical steel material. They are used to fabricate building structure grids, columns, and mechanical supports, which can reduce weight by 20-40% of the metal, and enable factory-standard mechanized construction. Using steel pipes to build highway bridges not only saves steel and simplifies construction, but also significantly reduces the area requiring protective coating, thereby cutting costs for investment and maintenance.