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Detailed Description of Pre-Galvanized Steel Pipe
Pre-galvanized pipe, sometimes referred to as mill-galvanized or in-line galvanized pipe, utilizes a different method for zinc protection. Different from post-galvanizing (hot-dip galvanizing), pre-galvanizing uses a steel strip that has been galvanized when the strips are made into pipes in a continuous process. The steel strip is galvanized and rolled into a tube using rollers. The edges of the tube are joined together with high-frequency induction welding. After welding is done, the exterior weld seam received a coating of zinc-rich invective spray to restore corrosion resistance. This is very fast and makes very smooth and uniform pipe, making it visually pleasing for many different applications.
Key Parameters for Pre-Galvanized Steel Pipe
| Parameter | Details |
|---|---|
| Manufacturing Process | ERW process using pre-galvanized steel coils |
| Base Material Standard | ASTM A653, EN 10346 |
| Pipe Standard | EN 10219, BS 4568, JIS G3444 |
| Steel Grade | Q195, Q235, S235, DX51D |
| Size Range (OD) | 21.3mm – 165mm 1/2" – 6" |
| Wall Thickness (WT) | 0.8mm – 5.0mm |
| Zinc Coating | Typically Z80 to Z275 80–275 g/m² |
| Surface Finish | Bright, smooth, uniform |
| Pipe Ends | Plain End |
Frequently Asked Questions (FAQ)
Q
What is the difference between pre-galvanized and hot-dip galvanized steel pipe?
Pre-galvanized pipe is made from steel strips that are galvanized before being formed into a pipe using the ERW process, resulting in a smooth, uniform surface. Hot-dip galvanized pipe is formed first and then immersed in molten zinc, providing a thicker and more uneven zinc coating. Pre-galvanized pipe is better suited for applications requiring a clean appearance, while hot-dip galvanized pipe offers heavier corrosion protection.
Q
What zinc coating weight is available for pre-galvanized steel pipe?
Pre-galvanized steel pipe is typically available with zinc coating weights ranging from Z80 to Z275, which corresponds to 80 g/m² to 275 g/m². The appropriate coating weight depends on the corrosion environment and the specific application requirements.
Q
What standards does pre-galvanized steel pipe comply with?
Pre-galvanized steel pipe can comply with multiple international standards. The base material typically meets ASTM A653 or EN 10346, while the finished pipe can conform to EN 10219, BS 4568, and JIS G3444, depending on the target market and application.
Q
What size range is available for pre-galvanized steel pipe?
Pre-galvanized steel pipe is available in an outer diameter (OD) range of 21.3mm to 165mm (approximately 1/2" to 6"), with wall thickness options from 0.8mm to 5.0mm. Custom sizes may be available depending on the manufacturer's capabilities.
Q
How is the weld seam protected on pre-galvanized steel pipe?
During the manufacturing process, the weld seam on the exterior of the pipe is treated with a zinc-rich spray coating immediately after high-frequency induction welding. This restores the corrosion resistance of the weld area, ensuring consistent protection along the full length of the pipe.
Q
What are the typical applications of pre-galvanized steel pipe?
Pre-galvanized steel pipe is widely used in applications that require a smooth, visually appealing finish combined with corrosion resistance. Common uses include construction scaffolding, greenhouse frameworks, fencing, electrical conduit systems, furniture frames, and general structural applications where aesthetics and moderate corrosion protection are both important.