SSAW steel pipe is a spiral seam welded steel pipe made of strip steel coil as raw material. It is often extruded at high temperature and welded by spiral submerged arc welding. The spiral steel pipe feeds the strip into the welded pipe unit, and the strip is rolled by multiple rolls and gradually rolled up to form a round tube blank with an opening gap, and the reduction of the extrusion rolls is adjusted for welding.
Large-diameter SSAW steel pipes are mainly used in water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction. For liquid transportation: water supply, drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: for piling pipes, for bridges; for wharfs, roads, building structures, etc.
Weld requirements for SSAW steel pipes
1. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the intergranular bonding of the weld will be poor, resulting in unfused or cracked.
2. If the gap is too small, the proximity effect will increase, the welding heat will be too large, and the weld will be burned; or the weld will form a deep pit after extrusion and rolling, which will affect the surface quality of the weld.
3. After heating the two edges of the tube blank 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 a firm weld is formed.
4. If the extrusion force of SSAW 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 being stressed. If the extrusion force is too large, the molten metal will be squeezed out of the weld, which 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.
Welding process of SSAW steel pipe
1. The raw materials are strip coil, welding wire and flux. They must undergo strict physical and chemical inspections before being put into operation.
2. The head and tail of the strip are butted by single wire or double wire submerged arc welding, and automatic submerged arc welding is used for repair welding after rolling into a steel pipe.
3. Before forming, the strip is leveled, trimmed, planed, surface cleaned and conveyed and pre-bending.
4. The electric contact pressure gauge is used to control the pressure of the cylinders on both sides of the conveyor to ensure the smooth conveying of the strip.
5. Adopt external control or internal control roll forming
Advantages of SSAW Steel Pipe
1. During the forming process, the deformation of the steel plate is uniform, the residual stress is small, and the surface is not scratched. The processed SSAW steel pipe has greater flexibility in the size range of diameter and wall thickness, especially in the production of high-grade steel-grade thick-walled pipes, especially small and medium-diameter thick-walled pipes, which have incomparable advantages over other processes.
2. Using advanced spiral submerged arc welding technology, welding can be realized in the best position, and defects such as misalignment, welding deviation and incomplete welding are not easy to occur, and the welding quality is easy to control.
3. Carry out 100% quality inspection on steel pipes, so that the whole process of steel pipe production is under effective inspection and monitoring, which effectively guarantees product quality.
4. All the equipment of the whole production line has the function of networking with the computer data acquisition system to realize the real-time data transmission, and the technical parameters in the production process are checked by the central control room.
Large-diameter SSAW steel pipes are mainly used in water engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction. For liquid transportation: water supply, drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: for piling pipes, for bridges; for wharfs, roads, building structures, etc.
Weld requirements for SSAW steel pipes
1. If the gap is too large, the proximity effect will be reduced, the eddy current heat will be insufficient, and the intergranular bonding of the weld will be poor, resulting in unfused or cracked.
2. If the gap is too small, the proximity effect will increase, the welding heat will be too large, and the weld will be burned; or the weld will form a deep pit after extrusion and rolling, which will affect the surface quality of the weld.
3. After heating the two edges of the tube blank 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 a firm weld is formed.
4. If the extrusion force of SSAW 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 being stressed. If the extrusion force is too large, the molten metal will be squeezed out of the weld, which 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.
Welding process of SSAW steel pipe
1. The raw materials are strip coil, welding wire and flux. They must undergo strict physical and chemical inspections before being put into operation.
2. The head and tail of the strip are butted by single wire or double wire submerged arc welding, and automatic submerged arc welding is used for repair welding after rolling into a steel pipe.
3. Before forming, the strip is leveled, trimmed, planed, surface cleaned and conveyed and pre-bending.
4. The electric contact pressure gauge is used to control the pressure of the cylinders on both sides of the conveyor to ensure the smooth conveying of the strip.
5. Adopt external control or internal control roll forming
Advantages of SSAW Steel Pipe
1. During the forming process, the deformation of the steel plate is uniform, the residual stress is small, and the surface is not scratched. The processed SSAW steel pipe has greater flexibility in the size range of diameter and wall thickness, especially in the production of high-grade steel-grade thick-walled pipes, especially small and medium-diameter thick-walled pipes, which have incomparable advantages over other processes.
2. Using advanced spiral submerged arc welding technology, welding can be realized in the best position, and defects such as misalignment, welding deviation and incomplete welding are not easy to occur, and the welding quality is easy to control.
3. Carry out 100% quality inspection on steel pipes, so that the whole process of steel pipe production is under effective inspection and monitoring, which effectively guarantees product quality.
4. All the equipment of the whole production line has the function of networking with the computer data acquisition system to realize the real-time data transmission, and the technical parameters in the production process are checked by the central control room.
