(1) welded pipe from steel plate welding into the round pipe, divided into high frequency resistance welded pipe (ERW welded pipe), straight seam arc welding pipe (LSAW), spiral welded pipe.Electrical engineering with "SC", can be used as water gas pipe can also be used as threading pipe, relatively thick.

(2)  Pipeline pipe, also known as wire pipe, is relatively thin, denoted by "T", and can only be used for threading.ERW steel pipeERW steel pipe

(3)  ERW tube is "high frequency resistance welding steel tube", and the common welding process is different, the weld line is from the base material of the steel belt body melted, the mechanical strength is better than the general welding.ERW stands for resistance welding, resistance welding has the characteristics of high production efficiency, low cost, material saving and easy automation, so it is widely used in aviation, aerospace, energy, electronics, automotive, light industry and other industrial sectors, is one of the important welding processes.

電縫鋼管の製造方法：  

Uncoiling --- 2. Leveling --- 3. End cutting --- 4. End shearing welding --- 5. Supercoil accumulator --- 6. Edge cutting --- 7. Ultrasonic detection --- 8. Forming --- 9. Electric induction welding --- 10. Ultrasonic detection for weld seam --- 11. Medium frequency heat treatment --- 12. Air cooling --- 13. Water cooling --- 14. Sizing --- 15. Flying cutting --- 16. Flush-out --- 17. Cropping --- 18. Flattening testing --- 19. Straightening --- 20. End facing and bevelling --- 21. Hydrodynamic testing --- 22. Ultrasonic detection for weld seam --- 23. Ultrasonic detection for pipe end --- 24. Visual and dimensions inspection --- 25.Weighting and measuring --- 26. Marking --- 27. Coating --- 28. Pipe-end protection --- 29. Bending --- 30. Shipping