Q235A Q235B Galvanized Steel pipe

Galvanized pipe, also referred to as galvanized steel pipe, can be classified into hot-dip galvanized and electro-galvanized types. Hot-dip galvanizing produces a thick, uniform coating with strong adhesion and a long service life. In contrast, electro-galvanizing is more cost-effective, but the surface finish is less smooth and its corrosion resistance is weaker compared to hot-dip galvanized pipes.

Galvanized pipes are available in various forms, including galvanized round pipes, square pipes, seamless pipes, and welded pipes. Additionally, there are cold-galvanized steel pipes, but due to their very thin zinc layer, which easily peels off and provides poor corrosion resistance, cold-galvanized pipes are now prohibited for use in water supply systems.

Commonly used galvanized steel pipe grades: Q215A; Q215B; Q235A; Q235B, etc.

Applications

Hot-dip galvanized steel pipes are widely used in construction, machinery, coal mines, chemicals, electric power, railway vehicles, automobile industry, highways, bridges, containers, sports facilities, agricultural machinery, petroleum machinery, prospecting machinery, greenhouse construction and other manufacturing industries.

Galvanized steel pipe is a welded steel pipe with a hot-dip galvanized or electro-galvanized layer on the surface. Galvanizing can increase the corrosion resistance of steel pipes and prolong the service life. Galvanized pipes are widely used. In addition to being used as pipeline pipes for general low-pressure fluids such as water, gas, and oil, they are also used as oil well pipes and oil pipes in the petroleum industry, especially in offshore oil fields, and oil heaters and condensers in chemical coking equipment. Pipes for coolers, coal distillation washing oil exchangers, and pipes for trestle piles, supporting frames for mine tunnels, etc.

Requirements for galvanized steel pipe:

The outer and inner surfaces of the pipe must be smooth and free from cracks, fissures, material coverage, and non-metallic inclusions. Small scratches, bumps, dents, a thin layer of welding slag or traces are allowed after removing defects produced during production, and avoid wall thicknesses below the allowable minimum. The weld must be dense and continuous, without cracks or other defects that reduce the tensile strength of the weld under the tensile strength of the base metal. The outer boss of the weld is removed. Seams are allowed to be thickened within the permitted diameter limits. The burr inside the weld has not been removed. The edge of the metal strip in the weld is not allowed to have unevenness. The end of the pipe must be cut perpendicular to its axis. Burrs on the pipe ends due to cutting technology processes are allowed. Deformation of the pipe ends is not allowed.

Galvanized pipe must have an adherent, continuous layer of zinc on the inner and outer surfaces. Zinc coverage of both surfaces or only the inner surface is achieved by immersion in a bath of molten zinc. Local roughening and thickening of the zinc layer is allowed, mainly in the section 80 mm from the end of the pipe, where blowing of the pipe is performed. The thickness of the zinc layer on the outer surface must be thinner than that on the inner surface. The inner surface must be approximately 56 µm thick. The linear mass of a galvanized pipe is calculated by adding the mass corresponding to the minimum thickness of the zinc layer to the mass of the pipe.