Details of L450 straight seam steel pipes for large-diameter straight seam steel pipes in industrial projects

First, the material and performance of L450 straight seam steel pipes

- Chemical composition: L450 belongs to pipeline steel, and its main chemical components include carbon (C), manganese (Mn), silicon (Si), etc., and also contain some trace elements such as niobium (Nb), vanadium (V), titanium (Ti), etc. The reasonable ratio of these elements makes the steel have good strength, toughness, and weldability.

- Mechanical properties: "L450" means that the minimum yield strength of the steel is 450MPa, with high tensile strength and deformation resistance, and can withstand the high pressure of media such as oil and natural gas during long-distance transportation. At the same time, it also has good low-temperature toughness and can maintain stable performance in special environments such as cold areas.

Second, the manufacturing process of L450 straight seam steel pipes

- Plate detection: Full-plate ultrasonic inspection of the steel plate used to manufacture steel pipes to detect whether there are defects inside the steel plate.

- Edge milling: Double-sided milling of the two edges of the steel plate is performed by the edge milling machine to ensure that the plate width, plate edge parallelism, and groove shape meet the requirements.

- Pre-bending: The plate edge is pre-bent by the pre-bending machine to make the plate edge have a suitable curvature.

- Forming: On the JCO forming machine, the pre-bent steel plate is subjected to multiple step-by-step stamping, first pressed into a "J" shape, then pressed into a "C" shape, and finally formed into an open "O" shape.

- Pre-welding: The formed straight seam welded steel pipe is joined and continuously welded by gas-shielded welding (MAG).

- Internal welding and external welding: The longitudinal multi-wire submerged arc welding is used to weld the inner and outer sides of the straight seam steel pipe respectively to obtain high-quality welds.

- Ultrasonic inspection I and X-ray inspection I: 100% ultrasonic inspection and X-ray industrial television inspection are carried out on the inner and outer welds of the straight seam welded steel pipe and the parent materials on both sides of the weld to detect the quality of the weld.

- Diameter expansion: Expand the diameter of the submerged arc welded straight seam steel pipe over the entire length to improve the dimensional accuracy of the steel pipe and improve the distribution of stress inside the steel pipe.

- Hydrostatic test: Inspect the expanded steel pipes one by one on the hydrostatic test machine to ensure that the steel pipes meet the test pressure required by the standard.

- Subsequent processing: Including chamfering, ultrasonic inspection II, X-ray inspection II, magnetic particle inspection of pipe ends, anti-corrosion, and coating processes to ensure the quality and corrosion resistance of the steel pipe.

Third, the application field of L450 straight seam steel pipe

- Oil and gas transportation: It is a common material for land and marine oil and natural gas pipelines. Its high strength and good corrosion resistance can withstand the erosion of high pressure and corrosive media during oil and gas transportation, ensuring the safe and stable operation of the pipeline.

- Chemical pipelines: They can be used in the chemical industry to transport various chemical media, such as acids, alkalis, salt solutions, and organic compounds. After special anti-corrosion treatment, it can resist the corrosion of different chemical media.

- Other fields: It can also be used in mining water-coal slurry pipelines, urban pipelines, offshore platforms, power stations, chemical industry, and urban building structures as structural support or fluid delivery pipelines.

Fourth, the advantages of L450 straight seam steel pipes

- High weld quality: A double-sided submerged arc welding process is adopted, the weld has good toughness, plasticity, uniformity, and density, and the weld is short, the probability of welding defects is small, and non-destructive testing is easy to achieve.

- High dimensional accuracy: After the overall mechanical expansion treatment, the internal stress of the steel pipe is small and evenly distributed, with high dimensional accuracy, which is convenient for on-site welding construction.

- A wide range of product specifications: It can produce both small-diameter and large-wall-thickness steel pipes and large-diameter and large wall thickness steel pipes to meet the needs of different projects.