(1) Raw materials are strip steel coils, welding wires, and fluxes. They must pass strict physical and chemical inspections before investing.
(2) The head-to-tail butt joint of large-diameter spiral steel pipes is single-wire or double-wire submerged arc welding, and active submerged arc welding repair welding is used after the steel pipe is rolled.
(3) Before forming, the strip is leveled, trimmed, planed, surface finished, transported, and pre-curved.
(4) The electric contact pressure gauge is used to control the pressure of the cylinders on both sides of the conveyor to ensure the smooth transportation of the strip.
(5) Use external control or internal control roll forming.
(6) The welding seam gap control equipment is selected to ensure that the welding seam gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the weld gap are all strictly controlled.
(7) Both internal welding and external welding use American Lincoln electric welding machine for single-wire or double-wire submerged arc welding, and then obtain stable welding quality.
(8) The welded seams after welding are all checked by an online ultrasonic active flaw instrument, which ensures 100% non-destructive testing coverage of spiral welds. If there are shortcomings. Actively alarm and spray symbols, and the production workers can adjust the process parameters at any time according to this to eliminate shortcomings in time.
(9) Use an air plasma cutting machine to cut the steel pipe into individual pieces.
(10) After cutting into single steel pipes, each batch of steel pipes must undergo a strict initial inspection system to check the mechanical properties, chemical composition, fusion status, surface quality of the steel pipes and pass non-destructive inspections to ensure that the pipe-making process is qualified. Only later can it be officially put into production.
(11) Where there are successive sonic flaw detection symbols on the weld, it shall be re-examined by manual ultrasonic and X-ray. If there are defects, after repairing, they shall pass the non-destructive inspection again until it is confirmed that the defects have been eliminated.
(12) The location pipes of the strip steel butt welding seam and the D-shaped joint intersecting the spiral welding seam are all viewed by X-ray television or filming.
(13) Each steel pipe passes the hydrostatic pressure test, and the pressure is radially sealed. The test pressure and time are strictly controlled by the steel pipe hydraulic microcomputer testing equipment. The experimental parameters are automatically printed and recorded.
(14) The pipe end is machined, so that the straightness, bevel angle and obtuse edge of the end face can be accurately controlled.
