What is the Difference between Seamless Pipe and ERW Pipe? The main application fields of the former are petroleum geological exploration, boilers, bearings, automobiles, aviation and so on. The latter can mainly transport oil, natural gas and other gas-liquid objects. It can meet the requirements of high and low pressure.
What is Seamless Pipe?
Seamless steel pipe is a steel pipe perforated by the whole round steel. And there is no weld on the surface. The production process is roughly as follows:
Raw material inspection: Before production, the raw material is strictly inspected to ensure that it meets the relevant standards before it can be put into production.
Blanking: The medium plate is generally used as the raw material. And the steel plate is opened into the required size by the cutting machine.
Heating perforation: the tube blank is placed in the induction ring. And the internal atoms collide with atoms to generate heat under the action of temperature, thus forming holes.
Pickling lubrication air drying (cold rolling not needed) : The use of chemical solution to corrode the inner and outer surfaces of the pipe to achieve the effect of rust removal.
Cold rolling (hot tying or heat treatment) : The tube blank is rolled or heat treated to achieve the desired steel tube properties.
Straightening: the steel pipe after rolling or treatment is straightened so that it reaches the specified straightness.
Finishing: the semi-finished product after the above process is inspected and marked accordingly for later use.
Finished product inspection: Strict inspection of the final product to ensure that its quality meets the relevant standards.
What is ERW Pipe?
ERW steel pipe, that is, straight seam resistance welded pipe, is a steel pipe made of resistance welding process. Here’s how it works:
Cutting edge: In order to make the tube blank width equal along the length direction. The tube blank needs to be cut edge to ensure that the weld gap is consistent after forming, so as to improve the quality of the weld.
Forming welding: The forming and welding process of steel pipe is usually used by continuous roll forming method or row roll forming method. In the continuous roll forming process, the tube billet is continuously plastic bent on a multi-stand mill to form a tube. The formed steel pipe is welded with high frequency resistance. And the weld is made of the base material of the steel strip body. And the mechanical strength is better than that of ordinary welding.
Solder solder removal: After the welding is complete, use the solder solder removal device to remove the inside and outside of the weld. The removal of external welding thorns is generally done by scraping and then rolling.
Sizing: Because the steel pipe is deformed by heat and pressure in the welding process, in order to improve the accuracy and roundness of the outer diameter of the finished pipe. The welded steel pipe needs to be sizing.
Finishing process: The steel pipe after sizing will be sawn, straightened, flat end, hydraulic test, inspection, wire and coating (or galvanized) finishing process.
Packaging factory: Finally, the finished steel pipe will be packaged and then shipped.
What is the Difference between Seamless Pipe and ERW Pipe
1. Production process: Seamless steel pipe is perforated by the whole round steel, without welding seams. According to the production method, the seamless steel pipe can be divided into hot-rolled seamless steel pipe, cold-rolled seamless steel pipe, cold-drawn seamless steel pipe, extruded seamless steel pipe, pipe jacking and so on. The ERW pipe, that is, the straight seam resistance welding pipe. It is welded by the steel plate, the weld is melted by the base material of the steel strip body. And the mechanical strength is better than that of the general welding. Resistance welding has the characteristics of high production efficiency, low cost, material saving and easy automation.
2. Appearance and structure: there is no weld on the surface of seamless steel pipe, while ERW steel pipe has a weld. This is also the key to the quality of both. Modern ERW production process and equipment have made its seamless has a more satisfactory solution, including geometric seamless and physical seamless.
3. Outer diameter and wall thickness tolerance: the ERW tube is cold-formed, and the diameter is determined by reducing the diameter. The process temperature is basically constant at room temperature, so the outer diameter is controlled accurately and the fluctuation range is small. The seamless steel pipe adopts hot rolling forming process, the outer diameter control is difficult to be accurate, and the fluctuation range is large. In addition, the ERW steel pipe uses hot rolled coil as the raw material. And the wall thickness tolerance can be controlled within a small range. The seamless steel pipe is produced by round steel perforation, and the wall thickness deviation is large.
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