Three forming methods of LSAW steel pipe

The production of LSAW steel pipes involves a series of advanced manufacturing equipment, including milling machines, edge pre-bending machines, forming presses, tack welding machines, and pipe expansion units. Each piece of equipment plays a critical role in ensuring dimensional accuracy, weld integrity, and overall pipe performance.LSAW pipes can be manufactured using several forming methods, with the most common being UOE, RBE, and JCOE processes. These methods differ in forming techniques, production efficiency, and application flexibility.

Three forming methods of LSAW steel pipe

LSAW steel pipes are primarily manufactured using three forming processes: JCOE, UOE, and HME (or RBE).

1.UOE Forming Process

The UOE process is one of the most widely used methods for producing large-diameter LSAW steel pipes.
First, the steel plate edges are pre-bent to reduce forming stress. Then, the plate is pressed into a “U” shape, followed by further pressing into an “O” shape to form a cylindrical pipe. After forming, internal and external submerged arc welding (SAW) is performed.
Once welding is completed, the pipe is usually expanded either at the ends or along its full length to improve roundness and dimensional precision. Pipes produced through this process are commonly referred to as UOE pipes.Key advantages of the UOE process include high production capacity and consistent quality, making it ideal for large-scale pipeline projects.

2.RBE (Roll Bending) Forming Process

In the RBE process, the steel plate is gradually bent into a cylindrical shape using rolling equipment. After forming, both internal and external submerged arc welding are carried out.Following welding, the pipe may undergo mechanical expansion to improve its geometry. If expanded, it is referred to as an RBE pipe; if not, it is called an RB pipe.This method offers flexibility in production and is suitable for various pipe sizes.

3.JCOE Forming Process

The JCOE process uses a progressive forming technique.The steel plate is first pressed into a “J” shape in multiple steps. Then, the opposite side is formed into another “J,” creating a “C” shape. Finally, the plate is pressed into an open “O” shape before welding.After welding, the pipe can be expanded to become a JCOE pipe, or left unexpanded as a JCO pipe.

Comparison: JCO vs UOE Forming Methods

The JCO forming method uses a multi-step progressive pressing approach, unlike the UOE process which relies on two main forming steps (U and O).
Because of this, JCO forming distributes deformation more evenly across the steel plate. This results in lower residual stress and minimizes surface damage such as scratches.
JCO technology offers greater flexibility in production. It can efficiently handle both large-volume and small-batch orders, as well as a wider range of pipe diameters and wall thicknesses. It is especially advantageous for manufacturing high-strength, thick-walled pipes, including medium and small diameters where other processes may struggle.

In contrast, the UOE process is characterized by high output and efficiency. Annual production capacity can typically reach 300,000 to 1,000,000 tons, making it highly suitable for mass production of standardized pipe specifications. However, it requires significant capital investment, which may be challenging for developing markets.

Production Process for LSAW Pipes

LSAW (Straight Seam Submerged Arc Welded) steel pipes are renowned for their high strength and exceptional quality control, making them the preferred choice for demanding engineering projects. The production process comprises the following key steps:

Steel Plate Preparation: High-quality steel plates are selected for LSAW pipe production; these plates typically comply with international standards such as API 5L or ASTM. Prior to manufacturing, the steel plates undergo Ultrasonic Testing (UT) to ensure they are free of internal cracks, voids, or other defects.
Plate Forming: The steel plates are formed into a tubular shape using the JCOE method. This involves sequential bending into J, C, and O shapes, culminating in the final formation of the pipe body. This process ensures precise diameter, excellent roundness, and dimensional accuracy.
Welding Process: Both the inner and outer seams are welded using the Submerged Arc Welding (SAW) technique. The inner seam is welded first, followed by the outer seam. This technique ensures that the weld quality is comparable to that of the base material, offering high reliability and superior mechanical strength.
Heat Treatment and Expansion: After welding, the pipes undergo heat treatment to relieve residual stresses generated during the welding process. Subsequently, mechanical expansion is performed to further enhance dimensional accuracy and surface quality.
Inspection and Acceptance: The finished pipes undergo rigorous inspection—including Ultrasonic Testing, X-ray testing, and hydrostatic testing—to verify their strength, leak-tightness, and compliance with standards. Finally, surface treatments such as epoxy coating or galvanizing are applied to extend the pipes' service life.

Conclusion

Choosing the right LSAW forming method depends on project requirements, including pipe size, wall thickness, production volume, and budget. UOE is ideal for large-scale standardized production, while JCOE provides flexibility and superior performance for high-grade and thick-wall applications.
By understanding these processes, buyers and engineers can make more informed decisions and ensure optimal pipeline performance.