Regarding the straight seam high-frequency welded steel pipe, high-frequency butt welding is used, including high-frequency contact welding and high-frequency induction welding, and the current frequency range is 350-450kHz. Its own production process is simple, production efficiency is high, cost is low, and the development is also relatively fast, so today we mainly come to understand its production characteristics!
1. Fast heating speed and high production efficiency
Due to the high concentration of energy in the welding area, the welding edge of the tube is heated to the temperature required for welding in a short time (a few hundredths of a second to a few tenths of a second), and there is no "skip-weld" phenomenon during high-speed welding, so a high welding speed can be obtained.
2. Adapt to a wide range of materials
High-frequency resistance welding belongs to the category of pressure welding, no need for external filler metal during welding, avoiding the chemical metallurgical reaction of welding materials and base metal and other problems, so it adapts to a wide range of materials, suitable for the welding of carbon steel, alloy steel, stainless steel and other metal materials.
3. The size of the welding heat affected zone is small
Because the welding speed is high and the workpiece has a strong self-cooling effect, the size of the welding heat-affected zone is small, and it is not easy to oxidize, and the weld can obtain better structural properties.
4. The steel pipe has uniform wall thickness and high dimensional accuracy
Straight seam high-frequency welded steel pipe is made of rolled steel strip after cold deformation and welding, and the wall thickness uniformity and surface quality are better than seamless steel pipe, especially the dimensional accuracy of steel pipe is far better than seamless pipe or submerged arc welded pipe. At the same time, due to the use of hot-rolled steel strip as raw material, the inherent defects of the pipe body (such as cracks, inclusions, pores, etc.) are very few, and it is used to replace seamless steel pipes in more and more applications. However, due to the limitation of forming equipment and heating power, the size and wall thickness of its pipe diameter are limited, and the current pipe diameter is below Φ600mm and the wall thickness is below 13mm.
In the past ten years, through the improvement of the quality of hot-rolled steel strip, as well as the improvement of computer control and online inspection automation level of welding and heat treatment parameters, the reliability of straight seam high-frequency welded steel pipe has been greatly enhanced. At present, in the oil and gas industry, longitudinal seam high-frequency welded steel pipes are widely used in long-distance pipelines, oil well casings and other fields.