Let’s take a look at how to address the issue of bending in precision welded pipes.

08 Dec,2022

Let’s take a look at how to address the issue of bending in precision welded pipes.

　　Let’s take a look at how to view it. Precision welded pipe Bending issue

　　Precision welded pipes are typically straight and very long, with lengths that can be quite substantial, though they are not particularly thick. For high‑precision tubing, the key attributes are its exceptional dimensional accuracy and superior toughness; as a result, such pipes are increasingly used in engineering applications. While most precision welded pipe sections are straight, manufacturing imperfections and process‑related issues can lead to significant bending. So how should bent precision pipe sections be corrected? In this case, a pipe straightening machine is required.

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　　1. Before starting, verify that the hydraulic system’s gear oil, as well as the reducer and gearbox oils, are fully topped up.

　　2. Prior to starting the main motor, conduct corner‑check optimization and adjust the hydraulic press system pressure.

　　3. Grease all lubrication points and inspect the gear transmission to ensure smooth and flexible operation.

　　4. Operators must wear appropriate personal protective equipment and, following a restart, may not transfer to another position or leave their post without authorization.

　　5. After the hydraulic system’s temperature and steam pressure have returned to normal, extend the straightening roll to its initial position.

　　6. Manual feeding: The seamless steel pipe is conveyed past the third pair of straightening rolls and then guided onto the straightening rolls, where it is pressed down and clamped.

　　7. Start the main motor; the seamless steel pipe rotates forward and is simultaneously straightened.

　　8. The motor stops, the straightening rollers cease straightening, the upper straightening roller extends, and the straightened seamless steel pipe is conveyed out.

　　9. If inversion and straightening are required, the server can be flipped by manually turning the inversion knob on the stage, enabling straightening in the opposite direction.

　　10. When the main motor stops, the straightening rollers cease straightening, and the seamless steel pipe is retracted to the starting position, awaiting the next repeated straightening sequence command.

　　11. After shutting down, ensure the main power switch is securely turned off, and do not arbitrarily modify the programmable controller.

　　Requirements for butt-welding pipe machines:

　　High Precision welded pipe It boasts superior precision in structural dimensions compared to conventional welded pipes, excellent weld quality and surface finish, and uniform wall thickness. Consequently, during the production of high‑precision welded pipes, the forming mill units and associated equipment must meet the following requirements:

　　1. High bending stiffness and forming/dimension‑setting frame: To minimize plastic deformation of the welded pipe mill under load, reduce the cumulative error along each motor shaft, and minimize compressive deformation, thereby enhancing the machining accuracy of precision welded pipes, it is essential to improve the strength and stiffness of the machine frame, the work rolls, the bearing housings, the tension‑relief rollers, and other mechanical components, as well as their dimensional accuracy. When selecting equipment, opt for extra‑heavy‑duty welded pipe mills and associated auxiliary systems.

　　2. Increase the number of forming stations by 2–3: To reduce compressive deformation, the primary and secondary processing stages should be correspondingly upgraded. Generally, Precision welded pipe The number of forming passes in a generator‑type forming process is 2 to 3 higher than that of a conventional welded pipe mill; consequently, the forming machine frame requires an additional 2 to 3 motor shafts.


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Next, let’s discuss the importance of proper maintenance and care for precision welded pipes.