In the oscillating welding of straight seam steel pipes, the welding current is slightly higher than that of traditional welding methods. Secondly, the tungsten electrode extension length in oscillating welding of straight seam steel pipes is determined according to the pipe wall thickness, typically 4-5 mm. The argon gas flow rate is slightly higher than that of traditional welding methods, approximately 8-10 L/min. Finally, the oscillation amplitude in oscillating welding of straight seam steel pipes is 2 mm from the blunt edge of the bevel on both sides of the fusion. The left and right hands should coordinate flexibly, oscillate evenly, and feed the wire evenly. The oscillating welding technology for straight seam steel pipes is generally used for welding thick-walled straight seam steel pipes. The technical parameters for welding straight seam steel pipes using the oscillating method differ slightly from the traditional straight welding method. Firstly, the tip of the argon arc welding nozzle is slightly thicker than that of the traditional straight welding method. Secondly, the weld joint assembly gap is also different. Taking a φ89×5 00Cr19Ni10 weld joint as an example, the gap in the traditional straight welding method is 0-3 mm, while in the oscillating method it is 4 mm. The welding specifications also differ.
Straight seam steel pipe expansion is a pressure processing technology that uses hydraulic or mechanical methods to apply force from the inner wall of the steel pipe, causing the pipe to expand radially outwards. Mechanical methods are simpler and more efficient than hydraulic methods, and are used in the expansion processes of several large-diameter straight seam steel pipe pipelines worldwide. The process is as follows: Mechanical expansion utilizes segmented fan-shaped blocks at the end of the expansion machine to expand radially, causing the pipe blank to undergo plastic deformation along its length in a step-by-step manner, achieving plastic deformation of the entire pipe length. It consists of five stages:
1. Initial Rounding Stage: The fan-shaped blocks open until all of them contact the inner wall of the steel pipe. At this point, the radii of all points within the inner circle of the steel pipe within the step length are almost uniform, and the steel pipe achieves initial rounding.
2. Nominal Inner Diameter Stage: The fan-shaped blocks reduce their speed from the initial position until they reach the required position, which is the desired inner circumference position of the finished pipe.
3. Springback Compensation Stage. The sector block begins to slow down further from its position in stage 2 until it reaches the required position, which is the inner circumference position of the steel pipe before the springback as required by the process design.
4. Pressure Holding and Stabilization Stage. The sector block remains stationary at the inner circumference position of the steel pipe before springback for a period of time. This is the pressure holding and stabilization stage required by the equipment and the expansion process.
5. Unloading and Retraction Stage. The sector block rapidly retracts from its inner circumference position before springback until it reaches the initial expansion position. This is the minimum shrinkage diameter of the sector block required by the expansion process.
What are the advantages of using straight seam steel pipe pipelines for fluid transportation?
1. Low infrastructure costs: Compared with railway transportation, infrastructure costs can be reduced by one-third, while the transportation capacity is twice that of railway.
2. Simple construction and fast construction speed: Generally laid underground, reliable, and adaptable to various terrains.
3. Low transportation and operating costs: A High degree of automation is possible. Compared with other transportation methods, straight seam steel pipe pipeline transportation is inexpensive, with freight costs only one-tenth that of railway and about half that of waterway.
Currently, the proportion of oil and gas transported using straight seam steel pipes worldwide is increasing, accounting for approximately 75%-95% of the total oil and gas volume. The range of transported substances is also expanding, encompassing not only petroleum and gas, but also various chemical raw materials and products. Research is underway on using straight seam steel pipes to transport solid substances.
What are the characteristics of welded steel pipes compared to seamless steel pipes?
1. Simpler production process.
2. Fewer equipment, simpler structure, lighter weight, and easier to achieve continuous, automated, and mechanized production.
3. Lower product cost.
4. Wide range of applicable specifications, diameter 6-3100mm, wall thickness 0.3-35mm.
Forming and welding are the basic processes in welded steel pipe production. Welded steel pipe production methods are classified according to the characteristics of these two processes. Based on the welding method, they can be divided into four types: furnace welding, electric welding, gas welding, and gas-electric welding.
1. Furnace welding: Based on the weld seam form, it is further divided into lap welding and butt welding. Butt welding is further divided into drawing and rolling. Drawing: Two types of equipment are used: chain furnace welding machines and continuous furnace welding machines. Rolling is done using continuous roller mills.
2. Electric Welding: Electric welding is divided into three types: contact welding, induction welding, and arc welding. Contact welding is further divided into resistance welding and flash welding. Arc welding is divided into open arc welding, submerged arc welding, and shielded arc welding. Submerged arc welding is further divided into straight seam and spiral seam welding.
3. Gas Welding: Gas welding is divided into acetylene welding and water gas welding. Water gas welding equipment is divided into roller pressing pipe welding machines and forging pressing pipe welding machines.
4. Gas-Electric Welding: Gas-electric welding is hydrogen atom welding.
Post time: Dec-24-2025