Black Seamless Hot Dip Galvanized Square Round Steel Pipes Rectangular Carbon Steel Pipe

1. High Strength & Toughness from Seamless Base Structure

• Seamless Forming for Structural Integrity: The "black seamless" base pipes are manufactured via hot extrusion, cold drawing, or piercing-rolling processes—no longitudinal welds to create weak points (e.g., pores, stress concentration). This ensures uniform mechanical performance:

• Tensile strength: 415–650MPa (depending on carbon steel grade, e.g., Q235B, Q345B);

• Yield strength: ≥235MPa (Q235B) to ≥345MPa (Q345B);

• Impact resistance: ≥27J at -20°C (for low-temperature scenarios), avoiding brittle fracture under load or temperature fluctuations.

• Load-Bearing Adaptability:

• Round seamless pipes excel in withstanding uniform pressure (e.g., fluid transmission pipelines), with working pressure up to 6.4MPa;

• Square/rectangular seamless pipes offer higher bending and torsional stiffness (e.g., a 100x100mm square pipe has 30% higher bending moment capacity than a 100mm-diameter round pipe of the same weight), ideal for structural supports (building columns, machinery frames).

2. Superior Corrosion Resistance via Hot Dip Galvanization

• Dual-Layer Zinc Protection: The black seamless pipes undergo hot dip galvanization (immersion in 440–460°C molten zinc), forming a dense, metallurgically bonded coating:

• Inner zinc-iron alloy layer (50–100μm thick): Wear-resistant and chemically stable, blocking corrosion from moisture, soil, or mild chemicals;

• Outer pure zinc layer (50–150μm thick): Acts as a sacrificial anode—zinc corrodes preferentially to protect the underlying steel, even if the coating is scratched.

• Long Service Life:

• In ordinary atmospheric environments: Service life of 30–50 years (5–8 times longer than ungalvanized seamless pipes);

• In harsh conditions (coastal salt spray, industrial fumes): Still maintains corrosion resistance for 15–25 years, reducing replacement frequency in outdoor/infrastructure projects.

• Zinc Coating Compliance: Meets international standards (e.g., ASTM A123, ISO 1461) with zinc coating weight ≥300g/㎡ (typically 300–500g/㎡), ensuring consistent anti-corrosion performance across the entire pipe surface (including inner walls, edges, and joints).

Galvanized steel pipe is a type of steel pipe with a layer of zinc coating on its surface, mainly used to improve the corrosion resistance of the steel pipe and extend its service life. This type of steel pipe is widely used in various fields such as construction, machinery, mining, chemical industry, energy agriculture, etc.

Hot dip galvanized pipes

Hot dip galvanized pipes produce an alloy layer by reacting molten metal with an iron substrate, thereby bonding the substrate and coating together. Hot dip galvanizing is the process of first pickling steel pipes. In order to remove iron oxide from the surface of the steel pipes, after pickling, they are cleaned in an ammonium chloride or zinc chloride aqueous solution or a mixed ammonium chloride and zinc chloride aqueous solution tank, and then sent to a hot-dip galvanizing tank. Hot dip galvanizing has the advantages of uniform coating, strong adhesion, and long service life.

Electroplated galvanized steel pipes

Electroplated galvanized steel pipe: Cold galvanizing, also known as electroplating galvanizing.It is made by depositing zinc on the surface of the steel pipe using the principle of electrolysis. The galvanizing amount is usually 10-50g/m ². Compared with hot-dip galvanized steel pipes, electroplated galvanized steel pipes have a thinner zinc layer, but they have the characteristics of good coating, bright and smooth appearance, and are suitable for outdoor environments or occasions that require beautiful appearance.