Primary Applications
1.Machinery Manufacturing & Structural Components
- Equipment Frames
- General Structural Tubing
2.Furniture & Decoration
- Metal Furniture
- Decorative Elements
3.Automotive Industry
4.Agriculture & Greenhouses:
5.General Fluid Transport:
6.Further Processing:
Material & Specifications:
Common Materials: Typically low-carbon steels such as Chinese grades Q195, Q215, Q235, or Japanese grades SPHC/SPHD. These grades inherently offer good weldability and moderate ductility, which is further enhanced by annealing.
"2.5mm Wall Thickness": This is a medium-thick wall, providing good structural strength and load-bearing capacity while still allowing for a degree of cold bending.
Black Annealed Steel Pipe and Galvanized Steel Pipe
| Feature | Black Annealed Steel Pipe | Galvanized Steel Pipe |
|---|---|---|
| Surface & Appearance | Dark gray/black matte finish (iron oxide layer). | Silvery-gray, shiny or spangled finish (zinc coating). |
| Core Process | Heat treatment (annealing) to relieve stress and improve ductility. | Zinc coating applied via hot-dip or electroplating for corrosion resistance. |
| Primary Purpose | Improved cold workability (bending, forming) and structural use. | Superior corrosion resistance for long-term exposure, especially outdoors. |
| Corrosion Resistance | Low. Oxide layer offers minimal protection; prone to rust if unprotected. | High. Zinc layer sacrificially protects the underlying steel from rust. |
FAQ: 2.5mm Black Annealed Steel Pipe
Q1: What exactly does "black annealed" mean?
A: "Black annealed" refers to a heat treatment process where the steel pipe is heated in a furnace with a controlled atmosphere (containing some oxygen) and then slowly cooled. This process creates a thin, dark iron oxide layer on the surface while relieving internal stresses and improving the pipe's ductility for better cold-working performance.
Q2: Can this pipe be used outdoors without painting?
A: Not recommended for long-term outdoor use without protection. The black oxide layer provides only minimal rust resistance. In exposed outdoor environments, it will begin to rust. For outdoor applications, additional protective coating (painting, powder coating) or using galvanized pipe is strongly advised.
Q3: What are the common available diameters?
A: It is typically available in a wide range of diameters, from small (e.g., 10mm, 1/2 inch) to large (over 200mm, 8 inches). The 2.5mm wall thickness is common in diameters from approximately 20mm to 150mm (3/4" to 6").
Q4: How does its price compare to galvanized pipe?
A: It is typically less expensive than hot-dip galvanized pipe of the same size. The galvanizing process adds significant cost. Black annealed pipe offers a cost-effective solution when corrosion resistance is not the primary concern.
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