Thin-walled spiral steel pipe concept: The strip steel is fed into the welded pipe unit. After rolling with multiple rollers, the strip steel is gradually rolled up to form a circular tube blank with an opening gap. The reduction amount of the extrusion roller is adjusted to make the weld gap Control it within 1~3mm, and make both ends of the welding port flush.
1. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the inter-crystal 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 and the welding heat will be too high, causing the weld to burn out; or the weld will form a deep pit after being extruded and rolled, affecting the surface quality of the weld.
After the two edges of the tube blank are heated to the welding temperature, under the squeeze of the extrusion roller, common metal grains are formed to penetrate and crystallize with each other and finally form a strong 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 cracking will occur after stress; 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, but also produces a large number of internal and external burrs, and even causes defects such as welding laps.
Thin-walled spiral steel pipe uses: National standard spiral steel pipes are mainly used in water supply projects, the petrochemical industry, the chemical industry, the electric power industry, agricultural irrigation, and urban construction. They are among the 20 key products developed in my country. For liquid transportation: water supply and drainage. For gas transportation: coal gas, steam, liquefied petroleum gas. For structural purposes: piling pipes, bridges; steel pipes for docks, roads, 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 executive standards include 5037, 9711, and API.
Thick-walled spiral steel pipe forming process:
1. Before forming the spiral steel pipe: The spiral steel pipe adopts the advanced double-sided submerged arc welding manufacturing process, which can be welded at the right position. It is not prone to defects such as wrong edges, 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 the correct welding position without any errors and defects, which can ensure the qualification of the spiral steel pipe and the quality is well guaranteed.
2. Spiral steel pipe forming: During the forming process of spiral steel pipe, the steel plate must be deformed evenly, with small residual stress, and no scratches on the surface. Therefore, the steel plate for making spiral steel pipes must be carefully selected, and the surface must be uniform without scratches. The processed spiral steel pipe has greater flexibility in the size range of diameter and wall thickness. Especially in the production of high-grade thick-walled pipes, especially small and medium-diameter thick-walled pipes, it has advantages that other processes cannot match and can meet the needs of Users who have more requirements in terms of spiral steel pipe specifications. The diameter and size specification range of spiral steel pipes must be flexibly grasped. Taking advantage of its advantages and the extensive needs of more users, spiral steel pipes can be popularized and promoted.
The development direction of thick-walled spiral steel pipe:
With the development of industry, engineering has put forward higher requirements for the use of spiral steel pipes. The reason why thick-walled spiral steel pipes appear is because the pressure generated by some media that need to be transported cannot be withstood by ordinary spiral steel pipes. If replaced by Straight seam steel pipes or seamless steel pipes will greatly increase the cost of the project. If it is a hazardous medium, we will inevitably increase the cost. Therefore, when choosing a pipeline, it is based on the medium that needs to be transported and the pressure that the medium will generate. decided.
Post time: Jan-25-2024