Straight seam welded pipes, steel pipes made by coil welding of hot-rolled or cold-rolled steel plates or steel strips, and pipes obtained by straight seam welding on welding equipment are called straight seam welded pipes. (It is named because the welding joint of the steel pipe forms a straight line). Seamless pipe is a long strip of steel with a hollow section and no seams around it.
1. Straight seam steel pipe production process
① Straight seam steel pipe high frequency welding process
According to the way that high-frequency current generates heat in the workpiece, it can be divided into contact high-frequency welding and induction high-frequency welding. When contacting high-frequency welding, high-frequency current is introduced into the workpiece through mechanical contact with the workpiece. During induction high-frequency welding, the high-frequency current generates an induced current in the workpiece through the coupling effect of the induction coil outside the workpiece. High-frequency welding is a highly specialized welding method, and special equipment must be equipped according to the product. High productivity, welding speed can reach 30m/min. That is to say, the weld seam is parallel to the surface of the steel pipe and will not be higher or lower than the surface of the steel pipe.
② Straight seam pipe submerged arc welding process
Submerged arc welding is also a welding method that uses arc as a heat source. During submerged arc welding, the arc burns under a layer of granular meltable flux, and the arc light is not exposed. Submerged arc welding gets its name from this, producing s Longitudinal double submerge arc welding (LSAW Steel Pipe). The metal electrode it uses is a continuously fed bare welding wire. Due to its large penetration depth, high productivity and high degree of mechanical operation, submerged arc welding is suitable for welding long welds of medium and thick plate structures. It is widely used in shipbuilding, boilers and pressure vessels, bridges, overweight machinery, nuclear power plant structures, marine structures, weapons and other manufacturing sectors. It is one of the most commonly used welding methods in today's welding production.
The above process differences mean that the submerged arc welding seam will be higher than the surface of the steel pipe, and the weld strength is much higher than that of the high-frequency welding process.
2. Production technology of seamless steel pipes
Seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → hydrostatic test (flaw detection )→mark→warehouse. This means that seamless steel pipes do not have the strength performance of welds. Seamless steel pipes are a production process in which round steel is perforated and formed in one go. However, the defect of seamless steel pipe lies in its production process.
Nowadays, the most advanced seamless steel pipe production technology will also cause the steel pipe to deviate from the wall. However, there is no deviating wall phenomenon when straight seam steel pipes are produced from flat steel plates or coiled plates and cut into sections. The wall deflection phenomenon will cause uneven stress on some steel pipe bodies, which can easily cause local rupture. The force on the straight seam steel pipe is uniform.
1. Straight seam steel pipe production process
① Straight seam steel pipe high frequency welding process
According to the way that high-frequency current generates heat in the workpiece, it can be divided into contact high-frequency welding and induction high-frequency welding. When contacting high-frequency welding, high-frequency current is introduced into the workpiece through mechanical contact with the workpiece. During induction high-frequency welding, the high-frequency current generates an induced current in the workpiece through the coupling effect of the induction coil outside the workpiece. High-frequency welding is a highly specialized welding method, and special equipment must be equipped according to the product. High productivity, welding speed can reach 30m/min. That is to say, the weld seam is parallel to the surface of the steel pipe and will not be higher or lower than the surface of the steel pipe.
② Straight seam pipe submerged arc welding process
Submerged arc welding is also a welding method that uses arc as a heat source. During submerged arc welding, the arc burns under a layer of granular meltable flux, and the arc light is not exposed. Submerged arc welding gets its name from this, producing s Longitudinal double submerge arc welding (LSAW Steel Pipe). The metal electrode it uses is a continuously fed bare welding wire. Due to its large penetration depth, high productivity and high degree of mechanical operation, submerged arc welding is suitable for welding long welds of medium and thick plate structures. It is widely used in shipbuilding, boilers and pressure vessels, bridges, overweight machinery, nuclear power plant structures, marine structures, weapons and other manufacturing sectors. It is one of the most commonly used welding methods in today's welding production.
The above process differences mean that the submerged arc welding seam will be higher than the surface of the steel pipe, and the weld strength is much higher than that of the high-frequency welding process.
2. Production technology of seamless steel pipes
Seamless steel pipe: round tube blank → heating → perforation → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → hydrostatic test (flaw detection )→mark→warehouse. This means that seamless steel pipes do not have the strength performance of welds. Seamless steel pipes are a production process in which round steel is perforated and formed in one go. However, the defect of seamless steel pipe lies in its production process.
Nowadays, the most advanced seamless steel pipe production technology will also cause the steel pipe to deviate from the wall. However, there is no deviating wall phenomenon when straight seam steel pipes are produced from flat steel plates or coiled plates and cut into sections. The wall deflection phenomenon will cause uneven stress on some steel pipe bodies, which can easily cause local rupture. The force on the straight seam steel pipe is uniform.
