Big MouthAbstract of the manufacturing steps for spiral steel pipes (1) The raw materials are strip coils, welding wire, and flux. Before investment, they must pass strict physical and chemical inspections. (2) The butt joints of large-diameter strip spiral steel pipes are single or double wire submerged arc welding, with active submerged arc welding for patch welding after pipe rolling. (3) Before forming, the steel strips are flattened, trimmed, planed, surface finished, transported, and pre-bent.
(4) The electrical contact pressure gauge is used to control the pressure of cylinders on both sides of the conveyor to ensure smooth transportation of strip materials. (5) Utilizes external or internal control roller forming. (6) Selects a weld gap control device to ensure that the weld gap meets welding requirements and strictly controls the pipe diameter, misalignment, and weld gap.
(7) Internally and externally, single or double wire flux-cored welding is performed using Lincoln electric welding machines, ensuring consistent welding quality. (8) All weld seams after welding are inspected by an online active ultrasonic flaw detector, guaranteeing 100% non-destructive testing coverage for spiral welds. Any defects are identified.
Alerts and spray symbols are actively issued, allowing production workers to adjust process parameters at any time to compensate for time shortages. (9) Steel pipes are cut into fragments using an air plasma cutting machine. (10) After cutting the pipes individually, each batch must undergo a strict initial inspection system to check the mechanical properties, chemical composition, fusion state, surface quality of the pipes, and pass non-destructive inspections to ensure the pipe-making process is qualified. Official production can only commence at a later stage.
(11) If there are continuous ultrasonic flaw detection symbols on the weld, the weld should be re-inspected with manual ultrasonic and X-ray. If defects are found, they must be re-inspected with non-destructive testing after repair until the defects are confirmed to be eliminated. (12) The locating pipes of the strip butt welds and the D-shaped joints intersecting the spiral welds are both examined with X-ray television or film. (13) Each steel pipe has passed a hydrostatic pressure test, with pressure being sealed radially. The test pressure and time are strictly controlled by the hydraulic microcomputer testing equipment for steel pipes. Experimental parameters will be automatically printed and recorded. (14) Mechanical processing of the pipe ends is conducted, with strict control over the flatness of the end faces, the angle of obliquity, and the angle of dullness.
