Production Process of Large Diameter Thick-walled Square Tube

　　Production process of large diameter thick-walled square tube are as follows:

　　The first step: Raw materials that strip, wire, flux. In the input before going through a rigorous physical and chemical testing.

　　The second step: The end of the strip butt joint, the use of single or double wire submerged arc welding, rolled into large diameter thick-walled square tube automatic submerged arc welding.

　　The third step: Before forming, strip through leveling, trimming, planing, surface cleaning and conveying to the bending treatment.

　　The fourth step: The use of electric contact pressure gauge control conveyor pressure on both sides of the press to ensure a smooth strip delivery.

　　The five step: The use of external control or roller molding.

　　The six step: Large-diameter thick-walled square tube weld seam gap control device used to ensure the weld gap to meet the welding requirements, pipe diameter, the wrong side of the amount and weld gap have been strictly controlled.

　　The seventh step: Large-diameter thick-walled square tube wall welding is divided into internal and external welding, are used by the United States Lincoln welding machine for single-wire or double-wire submerged arc welding to obtain a stable welding specifications.

　　The eighth step: Weld large-diameter thick-walled square tube welded continuous online ultrasonic testing after injury, to ensure that 100% of the spiral weld non-destructive testing coverage. If there are defects, automatic alarm and spray mark, the production workers so adjust the process parameters at any time, promptly eliminate defects.

　　The nine step: The air plasma cutting machine will be cut into large single-tube thick-walled square tube.