Steel pipes that are longitudinally submerged arc welded (LSAW) are essential components in a variety of industries, particularly the transportation of oil and gas. LSAW steel pipe production is a complicated and precise process with a few important steps. The intricacies of each stage of the LSAW steel pipe production process will be discussed in detail in this article, highlighting the significance of quality control and cutting-edge technology in the production of these high-performance pipes.
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Plate Detection:
A crucial step in quality control begins the LSAW steel pipe manufacturing process: plate recognition. To guarantee the quality of the raw materials, steel plates go through a stringent ultrasonic inspection in this initial phase. High-frequency sound waves are used in this non-destructive testing method to find internal flaws, inconsistencies, or defects in the steel plate that might not be visible to the naked eye.
Laminations, inclusions, and other structural anomalies that could jeopardize the final product's integrity can all be easily detected with ultrasonic testing. The plates are checked completely, and any recognized imperfections are set apart for additional assessment or dismissal. Because it establishes the foundation for the quality of the entire production of LSAW pipes, this meticulous inspection procedure is essential.
Edge Milling:
The steel plates proceed to the edge milling stage after passing the initial quality check. A fully automatic edge milling machine is used in this procedure to precisely shape the steel plate's longitudinal edges. To produce the appropriate groove shape for welding and attain the necessary plate width, the machine mills both sides of the plate simultaneously. In the manufacturing process of LSAW pipes, edge milling serves several important functions:
• It guarantees the specific width details of the plate are met, which is vital for accomplishing the ideal line measurement.
• It provides a smooth, clean edge that is necessary for high-quality welding. The groove shape created at this stage makes it easier for subsequent welding processes to properly penetrate and fuse the weld.
The quality of the final weld seam and, as a result, the LSAW steel pipe's overall structural integrity are directly influenced by the precision of the edge milling process.
Pre-bending:
The steel plate goes through a pre-bending process before being edge milled. A specialized pre-bending machine that uses controlled force to bend the plate's edges is used for this step. The primary objective of pre-bending is to set up the plate for the subsequent expansion, welding, and forming operations. There are several advantages to pre-bending:
• In subsequent stages, it lessens the strain placed on the forming equipment.
• During the main forming process, it helps achieve a more uniform curvature.
• It limits the gamble of imperfections or irregularities in the line's shape.
The steel grade, plate thickness, and final pipe diameter all play a role in determining the degree of pre-bending. The subsequent forming process can achieve the desired pipe geometry with minimal material stress thanks to this level of precision.
Forming:
The forming stage is where the flat steel plate takes on its cylindrical shape. There are different forming methods employed in LSAW steel pipe manufacturing, with the two most common being UOE and JCOE.
UOE (U forming, O forming, internal welding, external welding, mechanical cold expansion):
• U forming: The plate is bent into a U-shape using a powerful press.
• O forming: The U-shaped plate is further pressed to form an open-seam cylindrical shape.
• Internal and external welding: The seam is welded from both inside and outside.
• Mechanical cold expansion: The welded pipe is expanded to achieve precise dimensional accuracy.
JCOE ("J-C-O-E" pre-welding, forming, welding, cold expansion):
• J-forming: The plate edges are crimped to form a J-shape.
• C-forming: The plate is bent into a C-shape.
• O-forming: The C-shape is closed to form a cylinder.
• Welding: The seam is welded.
• Expansion: The pipe is expanded for dimensional accuracy.
Both methods have their advantages, and the choice often depends on factors such as the pipe diameter, wall thickness, and specific project requirements.
Pre-welding:
Before the fundamental welding process, a pre-welding step is performed utilizing high-power consistent dynamic gas protected bend welding (MAG). Before the subsequent internal and external multi-wire submerged arc welding, this quick seam pre-welding procedure is an essential step in the process's preparation. There are several advantages to pre-welding:
• It temporarily holds the shape of the pipe, keeping the edges in line.
• It creates an initial seal that shields the main welding process from contamination.
• It aids in the management of heat input and lowers the likelihood of distortion during the final stages of welding.
This is a crucial step in ensuring the LSAW steel pipe's overall integrity because the quality of the pre-weld has a significant impact on the quality of the final weld.
Internal and External Welding:
The last welding stage includes both interior and outside welding processes, normally utilizing longitudinal multi-wire lowered circular segment welding (SAW) innovation. Deep penetration and high welding efficiency are guaranteed by this approach.
• Welding within: On the inside of the steel pipe, the first pass of welding is done. This inward weld gives the establishment to the line's solidarity and honesty.
• Welding outside: Following the inward weld, the line goes through outer welding. This cycle finishes the weld joint, guaranteeing full infiltration and combination.
The utilization of multi-wire SAW innovation takes into consideration high affidavit rates and astounding weld quality. The lowered bend process, where the welding circular segment is safeguarded by a sweeping of granular transition material, shields the weld pool from environmental defilement and results in spotless, top-notch welds.
China LSAW Steel Pipe:
China has turned into a huge player in the worldwide LSAW steel pipe market, with numerous makers embracing trend setting innovations to create top notch pipes. LONGMA GROUP is one such manufacturer, and it specializes in LSAW steel pipes made with the Longitudinally Submerged Arc Welding (LSAW) process， you can contact them straightforwardly at info@longma-group.com.
LONGMA GROUP has established itself as a reputable supplier on the international market thanks to its dedication to quality and adherence to international standards. Their LSAW steel pipes are fabricated utilizing best in class hardware and go through thorough quality control estimates all through the creation cycle.
LONGMA GROUP's LSAW method ensures high weld integrity and excellent mechanical properties, making their pipes suitable for demanding applications in oil and gas, water transportation, and construction sectors.
