The welding current in the swing welding of the straight seam steel pipe is slightly larger than that of the traditional welding method; secondly, the elongation of the tungsten electrode in the swing welding of the straight seam steel pipe is determined according to the wall thickness of the pipe, usually 4-5mm; the flow rate of argon gas is slightly larger than that of the traditional welding method, about 8-10l/min; the last is the swing welding of the straight seam steel pipe, the swing range is 2mm from the blunt edge of the groove on both sides of the fusion; the left and right hands cooperate flexibly, swing evenly, and wire feed evenly. The swing welding technology of straight seam steel pipe is generally used for welding thick wall straight seam steel pipe. The welding technical parameters of the swing straight seam steel pipe are slightly different from the traditional linear welding method. First, the end of the porcelain nozzle of argon arc welding is slightly thicker than that of the traditional linear welding method. Secondly, the gap between the welding joints is also different. difference.
Longitudinally welded pipe expansion is a pressure processing process that uses hydraulic or mechanical means to apply force from the inner wall of the steel pipe to expand the steel pipe radially outward. Compared with the hydraulic method, the mechanical method has simpler equipment and higher efficiency. It has been adopted in several large-diameter straight seam welded pipe pipeline expansion processes around the world. The process is: mechanical expansion uses the fan-shaped block at the end of the expansion machine Expanding in the radial direction to make the tube blank along the length direction in a step-by-step manner, the process of realizing the plastic deformation of the full tube length in sections. divided into 5 stages
1. Initial full circle stage. The fan-shaped blocks are opened until all fan-shaped blocks touch the inner wall of the steel pipe. At this time, the radii of all points in the inner circular pipe of the steel pipe within the step range are almost the same, and the steel pipe obtains a preliminary full circle.
2. Nominal inner diameter stage. The fan-shaped block starts to reduce the moving speed from the front position until it reaches the required position, which is the required position of the inner circumference of the finished tube.
3. Springback compensation stage. The fan-shaped block starts to lower the speed at the position of the second stage until it reaches the required position, which is the position of the inner circumference of the steel pipe before the spring back is required by the process design.
4. Stable pressure holding stage. The fan-shaped block remains stationary for some time at the inner circumference of the steel pipe before springing back, which is the pressure-holding and stable stage required by the equipment and diameter-expanding process.
5. Unloading and regression stage. The fan-shaped block retracts rapidly from the inner circumference of the steel pipe before springing back, until it reaches the initial diameter expansion position, which is the minimum shrinkage diameter of the fan-shaped block required by the diameter expansion process.
What are the advantages of using LSW pipes to transport fluids?
1. The infrastructure cost is low. Compared with railway transportation, the infrastructure cost can save three points, and the transportation volume is twice that of the railway.
2. The construction is simple and the construction speed is fast. It is generally laid underground, reliable, and adaptable to various terrains.
3. The operating cost of transportation is low, and a high degree of automation can be realized. Compared with other transportation methods, longitudinally welded pipe pipeline transportation is cheap, and its freight is only 10% of the railway and about 2% of the waterway.
At present, the proportion of oil and gas transported by straight seam welded pipes in the world is increasing, accounting for about 75%-95% of the total oil and gas. products, and has been researching the use of longitudinally welded pipes to transport solid substances. The development direction of longitudinally welded pipe pipeline transportation points to the direction of large diameter and high pressure.
What are the characteristics of welded pipes compared with seamless steel pipes?
1. The production process is simple.
2. Less equipment, simple structure, lightweight, easy to realize continuous, automatic, and mechanized production.
3. Low product cost.
4. It is suitable for a wide range of varieties and specifications, with a diameter of 6-3100mm and a wall thickness of 0.3-35mm.
Forming and welding are the basic processes of welded pipe production, and the production methods of welded pipes are classified according to the characteristics of these two processes. The welding method can be divided into four types: furnace welding, electric welding, gas welding, and gas-electric welding.
Furnace welding is divided into lap welding and butt welding according to the form of the weld seam. The forming method of butt welding is divided into two types: drawing and rolling. There are two types of equipment used in drawing: chain furnace welding machine and continuous furnace welding machine. Roll forming uses a continuous roll machine.
Electric welding is divided into contact welding, induction welding, and arc welding. Among them, contact welding is 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 divided into There are two types straight seam and spiral seam, and gas welding is divided into acetylene welding and water gas welding. The water gas welding equipment is further divided into rolling-type welding pipe machines and forging-type welding pipe machines. Gas electric welding is hydrogen atom welding.
Post time: Jun-06-2023