Long Seam Welded Pipe, also known as Longitudinal Submerged Arc Welded (LSAW) pipe, is a type of steel pipe manufactured by welding along its length. This pipe is created by rolling steel plates into a cylindrical shape and then welding the seam that runs parallel to the pipe's axis. The products are widely used in various industries, particularly in oil and gas transportation, water supply systems, and structural applications.
The process of making it begins with high-quality steel plates. These plates are carefully selected based on their chemical composition and mechanical properties to meet specific industry standards. The steel plates are then formed into a cylindrical shape using powerful rolling machines. Once the cylinder is formed, the edges along the length of the pipe are prepared for welding. This preparation may involve beveling the edges to ensure proper weld penetration and strength.
Long seam welded pipe is known for its high strength, reliability, and versatility. They can be manufactured in large diameters and with thick walls, making them suitable for high-pressure applications. The longitudinal welding process allows for precise control over the pipe's dimensions and properties, resulting in a product that can meet stringent quality requirements.
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Welding technology:
The welding technology used in the production of products is crucial to their quality and performance. The most common method used is Submerged Arc Welding (SAW), which is highly efficient and produces high-quality welds. In the SAW process, an electric arc is formed between the welding wire and the pipe material, generating intense heat that melts both the wire and the pipe edges.
What makes SAW unique is that the entire welding process occurs under a layer of granular flux material. This flux serves several important functions. It protects the weld pool from atmospheric contamination, stabilizes the arc, and provides alloying elements to enhance the weld's properties. As the weld cools, the flux solidifies into a slag layer that can be easily removed, revealing a clean, high-quality weld beneath.
The SAW process typically involves multiple passes. The first pass, known as the root pass, establishes the initial connection between the pipe edges. Subsequent passes, called fill and cap passes, build up the weld to the required thickness and shape. This multi-pass approach ensures full penetration and strong bonding throughout the pipe wall thickness.
Advanced welding technologies, such as tandem or multi-wire SAW systems, are often employed to increase productivity and maintain consistent weld quality. These systems use multiple welding wires simultaneously, allowing for faster welding speeds and improved control over the weld bead profile.
Quality control is a critical aspect of the welding process. Non-destructive testing methods, such as ultrasonic testing, radiographic testing, and magnetic particle inspection, are used to verify the integrity of the weld and ensure it meets the required standards.
Long Seam Welded Pipe Dimensions and Specifications:
The products are available in a wide range of dimensions and specifications to suit various applications. The dimensions of these pipes are typically defined by their outside diameter (OD) and wall thickness. The length of the pipe can vary based on transportation limitations and specific project requirements.
In terms of diameter, the products can be manufactured in sizes ranging from about 16 inches (406 mm) to over 100 inches (2540 mm). The upper limit of the diameter is often determined by the capabilities of the manufacturing equipment and transportation constraints.
Wall thickness is another crucial dimension, which can range from about 6 mm to 50 mm or more, depending on the application requirements. Thicker walls are typically used for high-pressure applications or where additional structural strength is needed.
The products are manufactured to meet various international standards and specifications. Some of the commonly used standards include:
•API 5L: This standard from the American Petroleum Institute covers pipes used in oil and gas pipelines.
•ASTM A252: This standard from ASTM International covers steel pipe piles.
•EN 10219: This European standard covers cold-formed welded structural hollow sections.
These standards define requirements for chemical composition, mechanical properties, dimensional tolerances, and testing procedures. Pipes can be manufactured to different grades within these standards, with higher grades generally indicating higher strength and toughness.
It's important to note that it can also be custom-manufactured to meet specific project requirements that may go beyond standard specifications.
Surface treatment:
Surface treatment is a crucial step in the production of long seam welded pipe, as it enhances their durability, corrosion resistance, and overall performance. Various surface treatment methods can be applied depending on the intended application of the pipe and the environment in which it will be used.
One of the most common surface treatments is external coating. This can include fusion-bonded epoxy (FBE) coating, which provides excellent corrosion protection. FBE coating involves applying a dry powder to the heated pipe surface, which then melts and forms a continuous protective layer. For more demanding environments, multi-layer coatings may be used, such as three-layer polyethylene (3LPE) or three-layer polypropylene (3LPP) systems.
Internal coating or lining is also often applied, especially for pipes used in water transportation or the oil and gas industry. Common internal coatings include epoxy linings, which protect against corrosion and can improve flow efficiency by reducing friction.
For some applications, galvanization may be used as a surface treatment. This process involves coating the pipe with a layer of zinc, which provides corrosion protection through both barrier and sacrificial protection mechanisms.
In addition to coatings, other surface treatments may include shot blasting or grit blasting to clean the surface and create a profile for better coating adhesion. Heat treatment may also be applied to relieve residual stresses from the welding process and improve the pipe's mechanical properties.
The choice of surface treatment depends on factors such as the pipe's intended use, environmental conditions, regulatory requirements, and cost considerations. Proper surface treatment is essential for ensuring the longevity and performance of the products in their intended applications.
Long seam welded pipe Supplier:
Choosing a reliable supplier for long seam welded pipe is crucial for ensuring the quality and performance of these critical components. When selecting a supplier, it's important to consider factors such as manufacturing capabilities, quality control processes, adherence to international standards, and track record in the industry.
LONGMA GROUP's products Welding Type: LSAW. If you are choosing your product manufacturers, welcome to contact us at info@longma-group.com.
