LSAW steel pipe is a pipe product made from a single medium-thick steel plate as raw material, which is pressed (curled) by a mold or forming machine to form a pipe blank, and then double-sided submerged arc welding is used to expand the pipe diameter in the process. Its product specifications range widely, with excellent weld toughness, plasticity, uniformity and density, as well as large pipe diameter, thick pipe wall, high pressure resistance, low temperature resistance and corrosion resistance. LSAW steel pipes have important application value in the construction of high-strength, high-toughness, and high-quality long-distance oil and gas pipelines. According to API standards, LSAW steel pipes are the only specified pipe type when passing through Class 1 and Class 2 areas such as alpine zones, seabed, and densely populated urban areas. LSAW steel pipes can be divided into three main types: UOE welded pipes, JCOE welded pipes and HME welded pipes according to different forming methods. The process flow, advantages and disadvantages and application scope of these three molding methods will be introduced in detail below.
UOE welded pipe refers to steel pipes made through processes such as U forming, O forming, internal welding, external welding and mechanical cold expansion. The specific process flow is as follows:
U Forming: After a single steel plate is pre-bent at the edge, it is formed into a U shape by a U-shaped forming machine;
O Forming: The U-shaped steel plate is formed into an O-shape through an O-shaped forming machine;
Internal Welding: Internal welding of the O-shaped pipe, that is, submerged arc welding inside the pipe;
External Welding: External welding of the welded pipe, that is, submerged arc welding outside the pipe;
Mechanical Cold Expansion: Use mechanical cold expansion equipment to expand the diameter of the welded pipe to meet the specified pipe diameter and wall thickness requirements.
UOE welded pipes are characterized by mature technology, high production efficiency, and stable and reliable pipe quality. They are widely used in oil and gas pipelines, structural engineering and other fields.
Advantages: mature technology and high production efficiency. The pipe quality is stable and reliable, and the weld quality is high. It is suitable for producing large-diameter, thick-walled steel pipes with high pressure resistance, low temperature resistance and corrosion resistance.
Disadvantages: Large equipment investment and complex production lines. The requirements for raw materials are higher and thicker steel plates are required.
JCOE welded pipe is a steel pipe that is processed by pre-welding, forming, welding and cold expansion according to the "J-C-O-E" process sequence. The specific process flow is as follows:
Pre-welding: Pre-welding two steel plates into a long tube;
Forming (C Forming): The pre-welded long tube is formed into a C shape through a C-shaped forming machine;
Welding (Joint Welding): Submerged arc welding of C-shaped pipes to form welded joints;
Cold Expansion: The welded pipe is expanded through cold expansion equipment.
The process flow of JCOE welded pipe is relatively simple, the production efficiency is high, and it is suitable for mass production.
Advantages: The process flow is relatively simple and the production efficiency is high. It can produce large quantities of steel pipes and is suitable for the production of medium and large diameter steel pipes.
Disadvantages: The weld quality is slightly worse than that of UOE welded pipes. The scope of application is relatively narrow and the requirements for raw materials are high.
HME welded pipe is a steel pipe made by mandrel rolling method according to the "C-C-O" process flow, such as forming, welding and cold expansion. The specific process flow is as follows:
Forming (C-C Forming): The steel plate is formed into a C shape through a mandrel roll forming machine;
Welding (Joint Welding): Submerged arc welding of C-shaped pipes to form welded joints;
Cold Expansion: The welded pipe is expanded through cold expansion equipment.
The process flow of HME welded pipe is simple and suitable for the production of large-diameter and thick-walled steel pipes.
Advantages: simple process and high production efficiency. It is suitable for the production of large diameter and thick wall steel pipes with relatively low cost.
Disadvantages: High quality requirements for welds, and the consistency and integrity of the welds need to be ensured. The requirements for raw materials are higher.
Advantages: high production efficiency and suitable for mass production. The welding quality is high, and the weld seam has good toughness and plasticity.
Suitable for various environments and engineering needs.
Disadvantages: Requires larger equipment investment and site space. The requirements for raw materials and processes are high, and the production process needs to be precisely controlled.
Taken together, different LSAW steel pipe forming methods have their own advantages and disadvantages. Choosing the appropriate process depends on factors such as production needs, raw material conditions, and technical level. UOE welded pipes are suitable for large-diameter, high-pressure-resistant pipes; JCOE welded pipes are suitable for the production of medium and large-diameter steel pipes; HME welded pipes are suitable for the production of large-diameter, thick-walled steel pipes, and the cost is relatively low.