Pre-welding process for LSAW steel pipe

The manufacturing processes for LSAW (Longitudinal Submerged Arc Welding) steel pipes, including UOE and JCOE methods, are designed to ensure continuous advancement. This involves finalizing the tube formation, shaping, and positioning of the weld seam, enhancing pipe dimensions, welding quality, and production efficiency.

Pre-welding Process:

- Tube Transportation:

After forming, the tube is transported by a roller conveyor to the pre-welding station.

- Rotation and Adjustment:

The tube is placed on a rotating roll, which adjusts the tube to position the weld seam at the top. Pressure rollers on both sides are applied to align the tube seam.

-Welding Preparation:

The welding torch is lowered and adjusted to track the weld seam. Protective gas (Ar + CO2) and cooling water are activated.

- Welding Execution:

Welding begins, and the condition is monitored continuously. Welding continues to the tube end, where the arc stops automatically with a delayed gas stop. The torch and pressure rollers are then lifted, and the tube is moved for further processing.

- Handling Welding Defects:

The pipe is inspected for welding defects, and necessary corrections are made.

Characteristics of the Pre-welding Process:

- Shielded Arc Welding:

Gas Mixture: The pre-welding process uses a mixture of Argon (Ar) and Carbon Dioxide (CO2) for shielded arc welding.

Continuous Movement: The weld seam is continuously welded at a fast speed to ensure efficiency.

- Seam Quality Variability:

Bevel Angle and Tube Shape: Variations in bevel angle, tube shape, longitudinal openings, and plate edge distortions can affect seam quality.

Real-time Adjustments: Due to these variations, real-time tracking and adjustments are needed to maintain a stable arc and accurate weld position.

- Process Characteristics:

Welding Speed: The speed of the welding process can impact seam quality.

Quality Factors: Factors such as seam quality, welding speed, and necessary adjustments introduce variability and require precise control.

Randomness and Adjustments: The process involves continuous changes and adjustments to accommodate seam variations, ensuring high-quality welding.

By following these procedures and characteristics, the manufacturing process of LSAW steel pipes ensures high efficiency and quality, meeting the necessary standards for various applications.