Spiral steel pipe is made of steel coiled coil as raw material, which is often heated, extruded, and welded by automatic double wire double-sided submerged arc welding technology.
(1) Raw materials (belt coils, welding wire and flux) must undergo strict physical and chemical testing before input.
(2) Single-wire or double-wire submerged arc welding shall be used for the butt joints of steel strips, and automatic submerged arc welding repair welding shall be adopted after rolling into steel pipes.
(3) Before forming, the strip must pass the following steps: leveling, trimming, planning, surface cleaning and pre-bending.
(4) The electric contact pressure gauge is used to control the pressure of the cylinder on both sides of the conveyor to ensure the smooth conveying of the strip.
(5) Adopt external control or internal control roll molding.
(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the weld gap are strictly controlled.
(7) Both internal and external welding are performed by single-wire or double-wire submerged arc welding using a Lincoln welding machine in the United States to obtain stable welding specifications.
(8) The welded welds are inspected to ensure 100% non-destructive testing coverage of the spiral welds. If there is a defect, the production worker adjusts the process parameters at any time to eliminate the defects in time.
(9) The steel pipe is cut into individual pieces by an air plasma cutting machine.
(10) After cutting into a single steel pipe, each batch of steel pipe shall undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion condition, surface quality of the steel pipe and non-destructive testing to ensure the pipe making process. After that, it can be officially put into production.