Large Diameter Welded Pipe

Thick-walled straight seam welded pipes refer to steel pipes with a wall thickness of 8mm or more, which are commonly known as thick-walled straight seam welded pipes. These pipes have better pressure resistance than thin-walled ones and are generally suitable for high-temperature and high-pressure applications, as well as bridge load-bearing steel structures.

The control measures for thick-walled straight seam welded pipes include: enhancing pre-production inspections of straight seam welded pipes and post-production casting quality; and improving the cleanliness of molten steel in thick-walled straight seam welded pipes through measures such as proper protective pouring.

① manufacturers of thick-walled straight seam welded pipes cool the molten iron to below 1150°C in contact with carbon bricks, forming a thin iron skin layer on the carbon brick surface to isolate the molten iron from the brick. This not only forms an iron skin layer but also a slag layer for protection. This viewpoint utilizes full-carbon micro-porous, even ultra-micro-porous carbon bricks, and strives to enhance their thermal conductivity to lower the surface temperature to below 1150°C.

② Utilize ceramic brick linings to isolate contact between iron water and carbon bricks. As carbon bricks are difficult to resist iron water erosion, only a ceramic brick layer is artificially constructed on the surface of the carbon bricks, which is known as the ceramic cup wall. The ceramic cup wall is useful when the carbon brick's resistance to iron water erosion matches that of ceramic refractory materials. The welding process of thick-walled straight seam pipes begins at the exit of the heating furnace. After the pipe billet is descaled with high-pressure water at the exit of the heating furnace, its front end is flash-welded to the tail end of the previous steel billet, which has already entered the rough rolling mill.