High-frequency welding of steel plate spiral pipes

Release date:

2021-10-27

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Steel Pipe Knowledge

The skin effect and proximity effect of alternating current are applied to high-frequency welding of steel plate‑rolled tubes. After roll forming, the steel strip is shaped into a circular tube blank with a fragmented cross‑section. One or a set of resistors (magnetic rods) rotates near the center of the induction coil inside the tube blank, establishing an electromagnetic induction circuit between the resistor and the open edge of the blank. Under the influence of the skin and proximity effects, intense localized heating occurs at the edges of the tube blank’s opening, rapidly raising the weld seam edges to the temperature required for welding.

　　The skin effect and proximity effect in alternating current are applied to Steel plate rolled pipe In high-frequency welding, after roll forming, the steel strip is shaped into a circular tube blank with a fragmented cross-section. One or a set of resistors (magnetic rods) rotates near the center of the induction coil within the tube blank, establishing an electromagnetic induction circuit between the resistor and the open edge of the tube blank. Under the influence of the skin effect and the proximity effect, intense localized heating occurs at the edge of the tube blank’s opening, rapidly raising the weld edge to the temperature required for welding.

　　Based on the principles of electromagnetic induction and the skin effect, proximity effect, and eddy‑current heating in conductors carrying alternating current, high‑frequency welding locally heats the steel at the weld edges to a molten state. Subsequent pressure from the rolls promotes intergranular bonding along the butt joint, thereby achieving a sound weld. High‑frequency welding is a type of induction welding (or pressure‑contact welding) that offers advantages such as the absence of filler metal, no spatter, a narrow heat‑affected zone, aesthetically pleasing welds, and excellent mechanical properties; for these reasons, it is widely employed in the production of coiled tubing.

　　Steel pipe casings, also known as steel protective sleeves, are used in the construction of manually excavated bored piles when soil conditions are unstable and reinforced‑concrete retaining walls are difficult to implement. A steel retaining wall is employed to protect the drilled cast‑in‑place pile, preventing borehole collapse and ensuring uninterrupted progress. The steel casing is a hollow cylindrical structure with open ends; it is fabricated from sheet metal and fitted around the pile shaft according to its diameter. It stabilizes the borehole wall, prevents collapse, isolates surface water, guides the drilling bit, secures the pile location, and protects and supports the original ground surface.

　　Guangxi Nanning Canghai Steel Co., Ltd. specializes in straight-seam welded pipes, steel plate‑rolled pipes, large‑diameter steel pipes, spiral pipes, spiral‑welded pipes, straight‑seam pipes, spiral steel pipes, and steel casing pipes. As a professional manufacturer of spiral pipes, the company boasts complete production lines, advanced manufacturing processes, state‑of‑the‑art equipment, and comprehensive testing facilities, backed by strong technical expertise.

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