The concept of thin-walled spiral steel pipe: the strip steel is fed into the welded pipe unit, rolled by multiple rollers, the strip steel is gradually rolled up to form a circular tube billet with an opening gap, and the reduced amount of the extrusion roller is adjusted to make the weld seam gap Control it at 1~3mm, and make both ends of the welding joint flush.
1. If the gap is too large, the proximity effect will be reduced, the heat of the eddy current will be insufficient, and the intergranular bonding of the weld will be poor, resulting in a lack of fusion or cracking.
2. If the gap is too small, the proximity effect will increase, the welding heat will be too large, and the weld seam will be burned; or the weld seam will form deep pits after extrusion and rolling, which will affect the surface quality of the weld seam.
After the two edges of the tube blank are heated to the welding temperature, under the extrusion of the extrusion roller, the common metal grains are formed to penetrate and crystallize each other and finally form a firm weld. If the extrusion force of the spiral steel pipe is too small, the number of common crystals formed will be small, the strength of the weld metal will decrease, and cracks will occur after being stressed; if the extrusion force is too large, the molten metal will be squeezed out of the weld, It not only reduces the strength of the weld seam, but also produces a large number of internal and external burrs, and even causes defects such as weld laps.
Use of thin-walled spiral steel pipe: National standard spiral steel pipe is mainly used in water supply engineering, the petrochemical industry, the chemical industry, the electric power industry, agricultural irrigation, and urban construction. It is the twenty key products developed by our country. Used for liquid transportation: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: such as piling pipes and bridges; pipes for docks, roads, and building structures, etc.
The concept of thick-walled spiral steel pipe: refers to a spiral steel pipe whose wall thickness is slightly thicker than that of ordinary spiral steel pipe. Compared with ordinary wall-thickness spiral steel pipes, the advantages are high compressive strength, high impact strength, high safety performance, and longer service life. The implementation standards are 5037, 9711, and API.
The forming process of thick-walled spiral steel pipe:
1. Before the spiral steel pipe is formed: the spiral steel pipe adopts the advanced double-sided submerged arc welding process, which can realize welding at the position, and it is not easy to have defects such as misalignment, welding deviation, and incomplete penetration, and it is easy to control the welding quality and position. The spiral steel pipe adopts a special welding process, which can be welded at a certain welding position without any errors and defects, which can ensure the qualification of the spiral steel pipe and the quality is well guaranteed.
2. In the forming of spiral steel pipe: During the forming process of spiral steel pipe, the steel plate should be uniformly deformed, the residual stress should be small, and the surface should not be scratched. Therefore, the choice of steel plate for making spiral steel pipe should be careful, and the surface should be uniform without scratches. The processed spiral steel pipe has greater flexibility in the size and specification range of diameter and wall thickness, especially in the production of high-grade thick-walled pipes, especially small and medium-sized thick-walled pipes, which have incomparable advantages over other processes and can meet Users have more requirements on the specifications of spiral steel pipes. The diameter and size specification range of the spiral steel pipe should be flexibly grasped. Taking advan of its own good advantages and the extensive needs of more users, the spiral steel pipe can be popularized and promoted.
The development direction of thick-walled spiral steel pipe:
With the development of industry, higher requirements have been put forward for the use of spiral pipes in engineering. The reason why thick-walled spiral pipes appear is that the pressure generated by some mediums that need to be transported is unbearable for ordinary spiral steel pipes. Straight seam steel pipe or seamless steel pipe will greatly increase the cost of the project. If it is a dangerous medium, it is inevitable for us to increase the cost. Therefore, when selecting a pipeline, it is based on the medium that the project needs to transport and the pressure that the medium will generate.
Post time: Jul-07-2023