Straight seam steel pipes are widely used in many fields, and their production quality control is the key to ensure their performance and operational safety. As an important type of steel pipe, straight seam steel pipes are widely used in infrastructure construction such as large-span power grid projects, building steel structure projects, power and ultra-high voltage transmission and distribution projects, mechanical engineering, cross-sea bridges, railway stations, airports, stadium steel structure projects, municipal pipeline networks, foundation piling, water and gas pipelines, road construction, etc. Its application range not only covers the construction of infrastructure, but also involves many important areas of modern cities and transportation networks.
1. Quality control of welding process
The welding quality of straight seam steel pipes directly affects their performance, especially in situations where they are subjected to pressure, weight and external environmental influences. To ensure welding quality, quality control must start from all aspects of the production process and accurately control every detail.
Inspection of welding wire and flux specifications
Welding is the most critical link in the production process of straight seam steel pipes. Therefore, it is very important to check whether the specifications of welding wire and flux meet the requirements of welding process. The selection of welding wire and flux needs to be carried out strictly in accordance with the process regulations to prevent welding quality accidents caused by the use of inappropriate materials. Improper use of welding wire may lead to insufficient strength of the welded joint, and even cracks, pores and other problems in later use.
Supervision of welding environment
The welding quality is greatly affected by environmental conditions, especially temperature and humidity. According to the welding process requirements, when the welding environment temperature is lower than 0℃ or the relative humidity is greater than 90%, defects in the welded joint may occur, so corresponding environmental control measures need to be taken. For example, in a low temperature environment, the welding quality can be improved by preheating the welding part, increasing the welding time and other methods.
Bevel size inspection
It is very important to check the bevel size before welding, including gap, blunt edge, angle, misalignment and other aspects. Only by ensuring that the bevel size meets the process requirements can the strength and sealing of the welded joint be guaranteed. For steel pipes of different specifications and uses, the adjustment of the bevel size should meet the specific welding process requirements, so as to ensure the stable performance of the steel pipe after welding.
Automatic submerged arc welding process control
In the process of automatic submerged arc welding, the selection of process parameters such as welding current, voltage and welding speed is crucial. If the welding current is too low, it may lead to insufficient welding and insufficient strength of the welded joint; if the current is too high, overheating is likely to occur, resulting in deformation or cracks in the welded joint. Therefore, the reasonable selection of welding process parameters, especially for the welding process of high-frequency straight seam steel pipes and submerged arc welding straight seam steel pipes, can greatly improve production efficiency and quality.
Strengthen the use efficiency of the arc starter plate at the pipe end
In the process of automatic submerged arc welding, the arc starter plate at the pipe end is an important part of welding. By rationally utilizing the length of the arc starter plate at the end of the steel pipe, the welding quality can be effectively improved. The use of the arc starter plate can reduce the high temperature impact at the beginning of the arc and prevent the instability of the molten pool, thereby improving the uniformity and quality of the welded joint.
Cleaning work before repair welding
Repair welding is another important link to ensure the quality of the welded joint. Before repair welding, the welding slag, oil stains, rust and other impurities in the welding area must be thoroughly cleaned. Any residue will affect the welding quality and even cause welding defects such as pores and slag inclusions. Therefore, preparation work before repair welding is essential.
2. Classification and production process of straight seam steel pipes
Straight seam steel pipes are mainly divided into high-frequency straight seam steel pipes (ERW Pipe) and submerged arc welding straight seam steel pipes (LSAW Pipe) according to the production process. These two production processes have their own characteristics and are suitable for different application requirements.
High-frequency straight seam steel pipe (ERW pipe)
High-frequency straight seam steel pipes are steel pipes that heat the steel strips with high-frequency currents, weld the edges of the steel strips to a certain temperature, and form longitudinal welds. The advantages of this process are high production efficiency, low cost, and good strength and sealing of welded joints. Due to its simple process, it is suitable for large-scale production, especially in some occasions with low pressure and low welding requirements.
Submerged arc welding straight seam steel pipe (LSAW pipe)
The production process of submerged arc welding straight seam steel pipes is complex, mainly by bending the steel plate into a tubular shape and performing submerged arc welding at the pipe seam. The welding quality of this type of steel pipe is high and it is suitable for applications with high pressure and special requirements. The submerged arc welding process can provide high welding strength and welding depth, and is suitable for steel pipes that need to withstand high pressure or special environmental influences.
3. Application fields of straight seam steel pipes
Straight seam steel pipes have been widely used in many fields due to their low cost and high production efficiency. In infrastructure construction such as large-span power grid projects, building steel structure projects, power and ultra-high voltage transmission and distribution projects, straight seam steel pipes have been widely used due to their good bearing capacity and corrosion resistance. In addition, straight seam steel pipes also play an important role in cross-sea bridges, water and gas pipelines, foundation piling and other fields.
Summary
The quality control of straight seam steel pipes involves everything from the selection of welding materials to the management of the welding environment to the precise control of each process parameter. This series of strict quality control measures ensures the high-quality production of straight seam steel pipes and provides a guarantee for their wide application in major infrastructure construction. With the continuous development and innovation of production processes, straight seam steel pipes will continue to show their huge potential and advantages in more fields.
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