Manufacturing and production process of large diameter welded pipe

The manufacturing process of large diameter welded pipes is a complex procedure that varies depending on factors such as pipe size, material, and intended usage. Selecting the appropriate manufacturing method ensures that the final product meets the required quality, performance, and durability standards. Below are the primary manufacturing processes used for large diameter welded pipes.

Manufacturing Processes of Large Diameter Welded Pipe

- Straight Seam Welded Pipe (LSAW Steel Pipe):

This method involves rolling steel plates into a cylindrical shape and welding the edges together along a straight seam. It is most suitable for the production of large-diameter, thick-walled welded pipes, commonly used in pipeline systems for transporting liquids, gases, and other media.

- Spiral Welded Pipe (SSAW Steel Pipe):

In this process, steel plates are rolled into a tube shape and then welded in a continuous spiral pattern. Spiral welded pipes are ideal for larger diameter and thicker-walled applications, such as those used in the transportation of oil, natural gas, or other fluids under high pressure.

- Drawing Method:

This technique is used for producing large-diameter, thin-walled welded pipes by drawing steel billets through a die. It is often employed when high surface quality and precise dimensional accuracy are critical.

- Cold Drawing Method:

In this method, steel billets are heated to an appropriate temperature before being drawn into the desired pipe shape. Cold drawing is typically used for manufacturing welded pipes with thin walls and high dimensional precision requirements.

Production Process of Large Diameter Welded Pipe

Raw Material Inspection: Before production begins, physical and chemical inspections are conducted on raw materials such as steel strip coils, welding wires, and fluxes to ensure they meet quality standards.

Edge Jointing and Welding: The edges of the steel strips are joined using single or double-wire submerged arc welding. After the steel strips are formed into pipes, automatic submerged arc welding is used for repair welding.

Pre-Forming Treatments: Prior to forming, the steel strip undergoes a series of treatments, including leveling, trimming, planing, surface cleaning, and pre-bending to prepare it for the rolling process.

Conveyor Control: An electric contact pressure gauge is used to monitor and adjust the pressure of the oil cylinders on both sides of the conveyor to ensure the strip is smoothly and consistently conveyed through the manufacturing process.

Forming: The steel strip is formed into a tube using either external control or internal control roll forming methods, which ensures that the pipe maintains the correct shape and structural integrity.

Weld Gap Control: A weld gap control device is used to ensure that the weld gap is within specified limits. During the forming process, strict control is maintained over the pipe diameter, misalignment, and weld gap to ensure high-quality welds.

Welding: Both internal and external welding are performed using electric welding machines with single-wire or double-wire submerged arc welding. This method is essential for achieving consistent and stable welding quality, ensuring the strength and reliability of the welded pipe.

By adhering to these detailed processes and standards, large diameter welded pipes are manufactured to meet the rigorous demands of industrial applications, ensuring long-term performance and safety in their intended use.